@misc{roesti_roesti_satokangas_boughman_chaturvedi_wolf_langerhans_2024, title={Predictability, an Orrery, and a Speciation Machine: Quest for a Standard Model of Speciation}, volume={16}, ISSN={["1943-0264"]}, DOI={10.1101/cshperspect.a041456}, abstractNote={Marius Roesti1,8, Hannes Roesti2,8, Ina Satokangas3, Janette Boughman4, Samridhi Chaturvedi5, Jochen B.W. Wolf6 and R. Brian Langerhans7 1Division of Evolutionary Ecology, Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland 2Department of Biology, Alte Kantonsschule Aarau, 5001 Aarau, Switzerland 3Organismal & Evolutionary Biology Research Programme, University of Helsinki, 00014 Helsinki, Finland 4Department of Integrative Biology, Ecology, Evolution, and Behavior Program, Michigan State University, Lansing, Michigan 48824, USA 5Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, Louisiana 70118, USA 6Division of Evolutionary Biology, Faculty of Biology, LMU Munich Biozentrum Martinsried, D-82152 Planegg-Martinsried, Germany 7Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina 27695, USA Correspondence: marius.roesti{at}unibe.ch ↵8 These authors contributed equally to this work.}, number={6}, journal={COLD SPRING HARBOR PERSPECTIVES IN BIOLOGY}, author={Roesti, Marius and Roesti, Hannes and Satokangas, Ina and Boughman, Janette and Chaturvedi, Samridhi and Wolf, Jochen B. W. and Langerhans, R. Brian}, year={2024}, month={Jun} }
 @article{rosso_langerhans_avigliano_2023, title={Editorial: Fish as sentinels of urbanization impacts in aquatic ecosystems}, volume={11}, ISSN={["2296-665X"]}, DOI={10.3389/fenvs.2023.1190398}, abstractNote={By 2030, urban areas are projected to house 60 per cent of people globally (United Nations, 2018). Cities tend to occur near water because of the fundamental need for freshwater, but also because of its diverse uses (travel, commerce, food production, power generation, flood management). In this context, urbanized landscapes represent a major threat to freshwater (Albert et al., 2020) and marine (Alter et al., 2020) organisms. Being one of the only vertebrates that inhabit all types of aquatic ecosystems, fish are good candidates to serve as sentinels of the impacts of urbanization. This topic Research Topic includes five key contributions examining changes in fish assemblages, populations and phenotypes, and their potential ecological, evolutionary and economic consequences caused by urban-induced changes. Major patterns in fish responses to urbanization may vary among species, type of aquatic ecosystems and biogeographic regions, and this was supported by the contributions of this topic including studies from diverse fish taxa, aquatic environments and regions around the world. Nearctic, Neotropical and Austral fish assemblages are covered as well as freshwater and marine ecosystems. The studies document important changes in fish facing urbanization at varying spatial and temporal scales. Temporal changes in taxonomic and functional diversity in the fish assemblage of an urban stream in Texas were assessed (Antoniazzi et al.) over a 30 year period (1989–1990 vs. 2018–2019). The occurrence of previously absent species resulted in increased functional diversity in the modern, more urbanized, time period. But certainly, these were not good news. The increase in functional diversity was supported by the addition of invasive generalist (e.g., blue tilapia) and native tolerant (e.g., redbreast sunfish, blacktail shiner) species. As these species were locally common in present-day assemblages, some sensitive sentinel species as Sabine shiner (Notropis sabinae) and blackspot shiner (N. atrocaudalis) were extirpated or drastically reduced responding to stream alterations. Moreover, all native invader species increased their abundance with urbanization. Indeed, worldwide freshwater fish homogenization is strongly determined by the species OPEN ACCESS}, journal={FRONTIERS IN ENVIRONMENTAL SCIENCE}, author={Rosso, Juan Jose and Langerhans, Randall Brian and Avigliano, Esteban}, year={2023}, month={Apr} }
 @article{stroud_moore_langerhans_losos_2023, title={Fluctuating selection maintains distinct species phenotypes in an ecological community in the wild}, volume={120}, ISSN={["1091-6490"]}, DOI={10.1073/pnas.2222071120}, abstractNote={Species’ phenotypic characteristics often remain unchanged over long stretches of geological time. Stabilizing selection—in which fitness is highest for intermediate phenotypes and lowest for the extremes—has been widely invoked as responsible for this pattern. At the community level, such stabilizing selection acting individually on co-occurring species is expected to produce a rugged fitness landscape on which different species occupy distinct fitness peaks. However, even with an explosion of microevolutionary field studies over the past four decades, evidence for persistent stabilizing selection driving long-term stasis is lacking. Nonetheless, biologists continue to invoke stabilizing selection as a major factor explaining macroevolutionary patterns. Here, by directly measuring natural selection in the wild, we identified a complex community-wide fitness surface in which fourAnolislizard species each occupy a distinct fitness peak close to their mean phenotype. The presence of local fitness optima within species, and fitness valleys between species, presents a barrier to adaptive evolutionary change and acts to maintain species differences through time. However, instead of continuously operating stabilizing selection, we found that species were maintained on these peaks by the combination of many independent periods among which selection fluctuated in form, strength, direction, or existence and in which stabilizing selection rarely occurred. Our results suggest that lack of substantial phenotypic evolutionary change through time may be the result of selection, but not persistent stabilizing selection as classically envisioned.}, number={42}, journal={PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, author={Stroud, James T. and Moore, Michael P. and Langerhans, R. Brian and Losos, Jonathan B.}, year={2023}, month={Oct} }
 @article{sanderson_astorg_haines_beaumont-courteau_langerhans_derry_hendry_2023, title={Freshwater fishes maintain multi-trait phenotypic stability across an environmental gradient in aqueous calcium}, ISSN={["1095-8649"]}, DOI={10.1111/jfb.15412}, abstractNote={AbstractReductions in a limiting nutrient might be expected to necessitate compromises in the functional traits that depend on that nutrient; yet populations existing in locations with low levels of such nutrients often do not show the expected degradation of functional traits. Indeed, logperch (Percina caprodes), pumpkinseed sunfish (Lepomis gibbosus) and yellow perch (Perca flavescens) residing in low‐calcium water in the Upper St. Lawrence River were all previously found to maintain levels of scale calcium comparable to those of conspecific populations in high‐calcium water. Yet it remains possible that the maintenance of one functional trait (i.e., scale calcium) under nutrient‐limited (i.e., low calcium) conditions could come at the expense of maintaining other functional traits that depend on the same nutrient. The present study therefore examines other calcium‐dependent traits, specifically skeletal element sizes and bone densities in the same fish species in the same area. Using radiographs of 101 fish from the three species across four locations (two in high‐calcium water and two in low‐calcium water), this new work documents multi‐trait “homeostasis” along the gradient of water calcium. That is, no effect of calcium regime (low‐calcium vs. high‐calcium) was detected on any of the measured variables. Further, effect sizes for the skeletal traits were very low − lower even than effect sizes previously documented for scale calcium. These results thus show that native fishes maintain phenotypic stability across a suite of functional traits linked to calcium regulation, perhaps pointing to an “organismal‐level homeostasis” scenario rather than a “trait‐level homeostasis” scenario.}, journal={JOURNAL OF FISH BIOLOGY}, author={Sanderson, Sarah and Astorg, Louis and Haines, Grant E. E. and Beaumont-Courteau, Sandrine and Langerhans, R. Brian and Derry, Alison M. M. and Hendry, Andrew P. P.}, year={2023}, month={May} }
 @article{deutsch_langerhans_flores_hartstone-rose_2023, title={The roar of Rancho La Brea? Comparative anatomy of modern and fossil felid hyoid bones}, volume={284}, ISSN={["1097-4687"]}, DOI={10.1002/jmor.21627}, abstractNote={AbstractAnimal vocalization is broadly recognized as ecologically and evolutionarily important. In mammals, hyoid elements may influence vocalization repertoires because the hyoid apparatus anchors vocal tissues, and its morphology can be associated with variation in surrounding soft‐tissue vocal anatomy. Thus, fossil hyoid morphology has the potential to shed light on vocalizations in extinct taxa. Yet, we know little about the hyoid morphology of extinct species because hyoid elements are rare in the fossil record. An exception is found in the Rancho La Brea tar pits in Los Angeles, California, where enough hyoids have been preserved to allow for quantitative analyses. The La Brea Tar Pits and Museum houses one of the largest and most diverse collections of carnivore fossils, including hyoid elements from the extinct felids Smilodon fatalis and Panthera atrox. Here, we found that extant members of Felinae (purring cats) and Panthera (roaring cats) showed characteristic differences in hyoid size and shape that suggest possible functional relationships with vocalization. The two extinct taxa had larger and more robust hyoids than extant felids, potentially reflecting the ability to produce lower frequency vocalizations as well as more substantial muscles associated with swallowing and respiration. Based on the shape of the hyoid elements, Panthera atrox resembled roaring cats, while Smilodon fatalis was quite variable and, contrary to suggestions from previous research, more similar overall to purring felids. Thus P. atrox may have roared and S. fatalis may have produced vocalizations similar to extant purring cats but at a lower frequency. Due to the confounding of vocalization repertoire and phylogenetic history in extant Felidae, we cannot distinguish between morphological signals related to vocalization behavior and those related to shared evolutionary history unrelated to vocalization.}, number={10}, journal={JOURNAL OF MORPHOLOGY}, author={Deutsch, Ashley. R. R. and Langerhans, R. Brian and Flores, Deanna and Hartstone-Rose, Adam}, year={2023}, month={Oct} }
 @article{vinterstare_bronmark_nilsson_langerhans_chauhan_hansson_hulthen_2023, title={Sex matters: predator presence induces sexual dimorphism in a monomorphic prey, from stress genes to morphological defences}, volume={77}, ISSN={["1558-5646"]}, DOI={10.1093/evolut/qpac030}, abstractNote={AbstractInducible defences allow prey to increase survival chances when predators are present while avoiding unnecessary costs in their absence. Many studies report considerable inter-individual variation in inducible defence expression, yet what underlies this variation is poorly understood. A classic vertebrate example of a predator-induced morphological defence is the increased body depth in crucian carp (Carassius carassius), which reduces the risk of predation from gape-size limited predators. Here, we report that among-individual variation in morphological defence expression can be linked to sex. We documented sexual dimorphism in lakes in which crucian carp coexisted with predators, where females showed shallower relative body depths than males, but not in a predator-free lake. When exposing crucian carp from a population without predators to perceived predation risk in a laboratory environment (presence/absence of pike, Esox lucius), we found that males expressed significantly greater morphological defence than females, causing sexual dimorphism only in the presence of predators. We uncovered a correlative link between the sex-specific inducible phenotypic response and gene expression patterns in major stress-related genes (POMC, MC3R, and MC4R). Together, our results highlight that sex-specific responses may be an important, yet underappreciated, component underlying inter-individual differences in the expression of inducible defences, even in species without pronounced sexual dimorphism.}, number={1}, journal={EVOLUTION}, author={Vinterstare, Jerker and Bronmark, Christer and Nilsson, P. Anders and Langerhans, R. Brian and Chauhan, Pallavi and Hansson, Bengt and Hulthen, Kaj}, year={2023}, month={Jan}, pages={304–317} }
 @article{vinterstare_bronmark_nilsson_langerhans_berglund_orjes_brodin_fick_hulthen_2021, title={Antipredator phenotype in crucian carp altered by a psychoactive drug}, ISSN={["2045-7758"]}, DOI={10.1002/ece3.7762}, abstractNote={AbstractPredator‐inducible defenses constitute a widespread form of adaptive phenotypic plasticity, and such defenses have recently been suggested linked with the neuroendocrine system. The neuroendocrine system is a target of endocrine disruptors, such as psychoactive pharmaceuticals, which are common aquatic contaminants. We hypothesized that exposure to an antidepressant pollutant, fluoxetine, influences the physiological stress response in our model species, crucian carp, affecting its behavioral and morphological responses to predation threat. We examined short‐ and long‐term effects of fluoxetine and predator exposure on behavior and morphology in crucian carp. Seventeen days of exposure to a high dose of fluoxetine (100 µg/L) resulted in a shyer phenotype, regardless of the presence/absence of a pike predator, but this effect disappeared after long‐term exposure. Fluoxetine effects on morphological plasticity were context‐dependent as a low dose (1 µg/L) only influenced crucian carp body shape in pike presence. A high dose of fluoxetine strongly influenced body shape regardless of predator treatment. Our results highlight that environmental pollution by pharmaceuticals could disrupt physiological regulation of ecologically important inducible defenses.}, journal={ECOLOGY AND EVOLUTION}, author={Vinterstare, Jerker and Bronmark, Christer and Nilsson, P. Anders and Langerhans, R. Brian and Berglund, Olof and Orjes, Jennie and Brodin, Tomas and Fick, Jerker and Hulthen, Kaj}, year={2021}, month={Jun} }
 @article{langerhans_goins_stemp_riesch_araujo_layman_2021, title={Consuming Costly Prey: Optimal Foraging and the Role of Compensatory Growth}, volume={8}, ISSN={["2296-701X"]}, DOI={10.3389/fevo.2020.603387}, abstractNote={Some prey are exceptionally difficult to digest, and yet even non-specialized animals may consume them—why? Durophagy, the consumption of hard-shelled prey, is thought to require special adaptations for crushing or digesting the hard shells to avoid the many potential costs of this prey type. But many animals lacking specializations nevertheless include hard-bodied prey in their diets. We describe several non-mutually exclusive adaptive mechanisms that could explain such a pattern, and point to optimal foraging and compensatory growth as potentially having widespread importance in explaining costly-prey consumption. We first conducted a literature survey to quantify the regularity with which non-specialized teleost fishes consume hard-shelled prey: stomach-content data from 325 teleost fish species spanning 82 families (57,233 stomach samples) demonstrated that non-specialized species comprise ~75% of the total species exhibiting durophagy, commonly consuming hard-shelled prey at low to moderate levels (~10–40% as much as specialists). We then performed a diet survey to assess the frequency of molluscivory across the native latitudinal range of a small livebearing fish, Gambusia holbrooki, lacking durophagy specializations. Molluscivory was regionally widespread, spanning their entire native latitudinal range (>14° latitude). Third, we tested for a higher frequency of molluscivory under conditions of higher intraspecific resource competition in Bahamian mosquitofish (Gambusia spp.). Examining over 5,300 individuals, we found that molluscivory was more common in populations with higher population density, suggesting that food limitation is important in eliciting molluscivory. Finally, we experimentally tested in G. holbrooki whether molluscivory reduces growth rate and whether compensatory growth follows a period of molluscivory. We found that consumption of hard-shelled gastropods results in significantly reduced growth rate, but compensatory growth following prior snail consumption can quickly mitigate growth costs. Our results suggest that the widespread phenomenon of costly-prey consumption may be partially explained by its relative benefits when few alternative prey options exist, combined with compensatory growth that alleviates temporary costs.}, journal={FRONTIERS IN ECOLOGY AND EVOLUTION}, author={Langerhans, Randall Brian and Goins, Taylor R. and Stemp, Kenzi M. and Riesch, Rudiger and Araujo, Marcio S. and Layman, Craig A.}, year={2021}, month={Mar} }
 @article{hulthen_hill_jenkins_langerhans_2021, title={Predation and Resource Availability Interact to Drive Life-History Evolution in an Adaptive Radiation of Livebearing Fish}, volume={9}, ISSN={["2296-701X"]}, DOI={10.3389/fevo.2021.619277}, abstractNote={Predation risk and resource availability are two primary factors predicted by theory to drive the evolution of life histories. Yet, disentangling their roles in life-history evolution in the wild is challenging because (1) the two factors often co-vary across environments, and (2) environmental effects on phenotypes can mask patterns of genotypic evolution. Here, we use the model system of the post-Pleistocene radiation of Bahamas mosquitofish (Gambusia hubbsi) inhabiting blue holes to provide a strong test of the roles of predation and resources in life-history evolution, as the two factors do not co-vary in this system and we attempted to minimize environmental effects by raising eight populations under common laboratory conditions. We tested a priori predictions of predation- and resource-driven evolution in five life-history traits. We found that life-history evolution in Bahamas mosquitofish largely reflected complex interactions in the effects of predation and resource availability. High predation risk has driven the evolution of higher fecundity, smaller offspring size, more frequent reproduction, and slower growth rate—but this predation-driven divergence primarily occurred in environments with relatively high resource availability, and the effects of resources on life-history evolution was generally greater within environments having high predation risk. This implies that resource-driven selection on life histories overrides selection from predators when resources are particularly scarce. While several results matched a priori predictions, with the added nuance of interdependence among selective agents, some did not. For instance, only resource levels, not predation risk, explained evolutionary change in male age at maturity, with more rapid sexual maturation in higher-resource environments. We also found faster (not slower) juvenile growth rates within low-resource and low-predation environments, probably caused by selection in these high-competition scenarios favoring greater growth efficiency. Our approach, using common-garden experiments with a natural system of low- and high-predation populations that span a continuum of resource availability, provides a powerful way to deepen our understanding of life-history evolution. Overall, it appears that life-history evolution in this adaptive radiation has resulted from a complex interplay between predation and resources, underscoring the need for increased attention on more sophisticated interactions among selective agents in driving phenotypic diversification.}, journal={FRONTIERS IN ECOLOGY AND EVOLUTION}, author={Hulthen, Kaj and Hill, Jacob S. and Jenkins, Matthew R. and Langerhans, Randall Brian}, year={2021}, month={Apr} }
 @article{vinterstare_ugge_hulthen_hegg_bronmark_nilsson_zellmer_lee_parssinen_sha_et al._2021, title={Predation risk and the evolution of a vertebrate stress response: Parallel evolution of stress reactivity and sexual dimorphism}, ISSN={["1420-9101"]}, DOI={10.1111/jeb.13918}, abstractNote={AbstractPredation risk is often invoked to explain variation in stress responses. Yet, the answers to several key questions remain elusive, including the following: (1) how predation risk influences the evolution of stress phenotypes, (2) the relative importance of environmental versus genetic factors in stress reactivity and (3) sexual dimorphism in stress physiology. To address these questions, we explored variation in stress reactivity (ventilation frequency) in a post‐Pleistocene radiation of live‐bearing fish, where Bahamas mosquitofish (Gambusia hubbsi) inhabit isolated blue holes that differ in predation risk. Individuals of populations coexisting with predators exhibited similar, relatively low stress reactivity as compared to low‐predation populations. We suggest that this dampened stress reactivity has evolved to reduce energy expenditure in environments with frequent and intense stressors, such as piscivorous fish. Importantly, the magnitude of stress responses exhibited by fish from high‐predation sites in the wild changed very little after two generations of laboratory rearing in the absence of predators. By comparison, low‐predation populations exhibited greater among‐population variation and larger changes subsequent to laboratory rearing. These low‐predation populations appear to have evolved more dampened stress responses in blue holes with lower food availability. Moreover, females showed a lower ventilation frequency, and this sexual dimorphism was stronger in high‐predation populations. This may reflect a greater premium placed on energy efficiency in live‐bearing females, especially under high‐predation risk where females show higher fecundities. Altogether, by demonstrating parallel adaptive divergence in stress reactivity, we highlight how energetic trade‐offs may mould the evolution of the vertebrate stress response under varying predation risk and resource availability.}, journal={JOURNAL OF EVOLUTIONARY BIOLOGY}, author={Vinterstare, Jerker and Ugge, Gustaf M. O. Ekelund and Hulthen, Kaj and Hegg, Alexander and Bronmark, Christer and Nilsson, Per Anders and Zellmer, Ursula Ronja and Lee, Marcus and Parssinen, Varpu and Sha, Yongcui and et al.}, year={2021}, month={Sep} }
 @article{sha_zhang_lee_bjorneras_skerlep_gollnisch_herzog_ekelund ugge_vinterstare_hu_et al._2021, title={Diel vertical migration of copepods and its environmental drivers in subtropical Bahamian blue holes}, volume={55}, ISSN={["1573-5125"]}, DOI={10.1007/s10452-020-09807-4}, abstractNote={AbstractDiel vertical migration (DVM) is the most common behavioral phenomenon in zooplankton, and numerous studies have evaluated DVM under strong seasonality at higher latitudes. Yet, our understanding of the environmental drivers of DVM at low latitudes, where seasonal variation is less pronounced, remains limited. Therefore, we here examined patterns of vertical distribution in copepods in six subtropical Bahamian blue holes with different food web structure and tested the role of several key environmental variables potentially affecting this behavior. Day and night samplings showed that copepods generally performed DVM, characterized by downward migration to deeper depths during the day and upward migration to surface waters at night. Across all blue holes, the daytime vertical depth distribution of calanoid copepods correlated positively with both predation risk and depth of food resources (Chlorophylla), but was less affected by ultraviolet radiation (UVR). A potential explanation is that since UVR is a continuous threat across seasons, zooplankton have established photoprotective pigmentation making them less vulnerable to this threat. The copepods also showed a size-structured depth segregation, where larger individuals were found at deeper depths during the day, which further strengthens the suggestion that predation is a major driver of DVM in these systems. Hence, in contrast to studies performed at higher latitudes, we show that despite the constant exposure to UVR, predator avoidance and food availability are the most pronounced drivers of copepod DVM at those low latitudes, suggesting that the main driver of DVM may vary among systems, but also systematically by latitude.}, number={4}, journal={AQUATIC ECOLOGY}, author={Sha, Yongcui and Zhang, Huan and Lee, Marcus and Bjorneras, Caroline and Skerlep, Martin and Gollnisch, Raphael and Herzog, Simon David and Ekelund Ugge, Gustaf and Vinterstare, Jerker and Hu, Nan and et al.}, year={2021}, month={Dec}, pages={1157–1169} }
 @article{bjorneras_skerlep_gollnisch_herzog_ugge_hegg_hu_johansson_lee_parssinen_et al._2020, title={Inland blue holes of The Bahamas - chemistry and biology in a unique aquatic environment}, volume={194}, ISSN={["1863-9135"]}, DOI={10.1127/fal/2020/1330}, abstractNote={: While lake systems in temperate regions have been extensively studied, tropical and subtropical systems have received less attention. Here, we describe the water chemistry and biota of ten inland blue holes on Andros Island, The Bahamas, representative of the morphological, abiotic, and biotic variation among Androsian inland blue holes. The majority of the studied blue holes were vertically stratified with oxic freshwater overlying anoxic saline groundwater of marine origin. Water chemistry (e.g. total phosphorus and nitrogen) in shallow waters was similar among blue holes, while turbidity and water color varied. Presence of hydrogen sulfide and reduced iron in and below the halocline indicate reducing conditions in all stratified blue holes. The biota above the halocline was also similar among blue holes with a few taxa dominating the phytoplankton community, and the zooplankton community consisting of copepods and rotifers. The Bahamas mosquitofish ( Gambusia hubbsi ) was present in all investigated blue holes, often accompanied by other small planktivorous fish, while the piscivorous bigmouth sleeper ( Gobiomorus dormitor ) was only present in some of the blue holes. Our field study reinforces that inland blue holes are highly interesting for biogeochemical research, and provide naturally replicated systems for evolutionary studies.}, number={2}, journal={FUNDAMENTAL AND APPLIED LIMNOLOGY}, author={Bjorneras, Caroline and Skerlep, Martin and Gollnisch, Raphael and Herzog, Simon David and Ugge, Gustaf Ekelund and Hegg, Alexander and Hu, Nan and Johansson, Emma and Lee, Marcus and Parssinen, Varpu and et al.}, year={2020}, month={Dec}, pages={95–106} }
 @article{langerhans_kern_2020, title={Urbanization and Evolution in Aquatic Environments}, ISBN={["978-0-19-883685-8"]}, DOI={10.1093/oso/9780198836841.003.0010}, abstractNote={Abstract
               Human impacts on freshwater and marine ecosystems have long been of special concern due to water’s essential role in ecosystem functioning and human civilization. Urban development causes a large number of changes in all types of aquatic environments, from small ephemeral pools to rivers to great lakes to expansive coastal habitats. These changes can strongly influence evolution of life in the water by altering selection, gene flow, and genetic drift. Yet our understanding of the evolutionary consequences of urbanization on aquatic organisms is still in early stages. This chapter reviews the impacts of urbanization on aquatic taxa, examining the evolutionary consequences (known or likely) of four major types of urban-induced changes to ecosystems: biotic interactions, physical environment, temperature, and pollution. By drawing connections between literature on ecological and evolutionary impacts in aquatic urban environments, the chapter concludes that (1) several anthropogenic factors seem to commonly drive evolutionary and phenotypic change (organic-compound pollution, altered temperature, and hydrologic shifts), (2) predictability of evolutionary changes are often taxa specific, and may commonly depend on the focal ‘scale’ (e.g., whole-organism performance, morphology, or gene), and (3) there are a few key ‘frontier topics’ (altered biotic interactions, artificial light, sound pollution, and fragmentation) where additional research on phenotypic evolution would be particularly informative.}, journal={URBAN EVOLUTIONARY BIOLOGY}, author={Langerhans, R. Brian and Kern, Elizabeth M. A.}, year={2020}, pages={157–174} }
 @article{lee_zhang_sha_hegg_ugge_vinterstare_skerlep_parssinen_herzog_bjorneras_et al._2019, title={Low-latitude zooplankton pigmentation plasticity in response to multiple threats}, volume={6}, ISSN={["2054-5703"]}, DOI={10.1098/rsos.190321}, abstractNote={Crustacean copepods in high-latitude lakes frequently alter their pigmentation facultatively to defend themselves against prevailing threats, such as solar ultraviolet radiation (UVR) and visually oriented predators. Strong seasonality in those environments promotes phenotypic plasticity. To date, no one has investigated whether low-latitude copepods, experiencing continuous stress from UVR and predation threats, exhibit similar inducible defences. We here investigated the pigmentation levels of Bahamian ‘blue hole’ copepods, addressing this deficit. Examining several populations varying in predation risk, we found the lowest levels of pigmentation in the population experiencing the highest predation pressure. In a laboratory experiment, we found that, in contrast with our predictions, copepods from these relatively constant environments did show some changes in pigmentation subsequent to the removal of UVR; however, exposure to water from different predation regimes induced minor and idiosyncratic pigmentation change. Our findings suggest that low-latitude zooplankton in inland environments may exhibit reduced, but non-zero, levels of phenotypic plasticity compared with their high-latitude counterparts.}, number={7}, journal={ROYAL SOCIETY OPEN SCIENCE}, author={Lee, Marcus and Zhang, Huan and Sha, Yongcui and Hegg, Alexander and Ugge, Gustaf Ekelund and Vinterstare, Jerker and Skerlep, Martin and Parssinen, Varpu and Herzog, Simon David and Bjorneras, Caroline and et al.}, year={2019}, month={Jul} }
 @article{riesch_martin_langerhans_2020, title={Multiple traits and multifarious environments: integrated divergence of morphology and life history}, volume={129}, ISSN={["1600-0706"]}, DOI={10.1111/oik.06344}, abstractNote={Understanding complex responses of multiple character suites (e.g. behaviour, life history, morphology) across multifarious environments is a challenging task. Here we use a multivariate approach (partial least squares structural equation modelling) to disentangle environmental drivers (i.e. predation, resource availability and population demographics) of population divergence in life history and morphology. We further employ a two‐block partial least squares analysis in a novel approach to uncovering integrated and independent aspects of divergence in correlated character suites. Examining Bahamas mosquitofish Gambusia hubbsi inhabiting blue holes, we found phenotypic divergence mainly resulted from differences in predation regimes, but demography and resources also proved important in particular aspects of divergence. We uncovered significant covariation among life histories and morphologies, and revealed that phenotypic divergence between predation regimes involved both integrated and independent responses. For instance, female life histories strongly diverged independently of morphology, while some morphological shifts (abdominal distension) resulted from changes in fecundity; males showed strong morphological divergence independent of life history, but much of their life‐history shifts reflected joint morphological changes (lean weight and body shape). Our study illustrates the utility of gathering disparate data types from multiple populations/species to better understand the causes and nature of phenotypic divergence in the wild.}, number={4}, journal={OIKOS}, author={Riesch, Ruediger and Martin, Ryan A. and Langerhans, R. Brian}, year={2020}, month={Apr}, pages={480–492} }
 @article{valdez_peterson_chen_steward_hannameyer_seebaluck_hulthen_langerhans_2019, title={Perceptions of Resilience in Fishery-Dependent Bahamian Communities Following a Category 4 Hurricane}, volume={44}, ISSN={["1548-8446"]}, DOI={10.1002/fsh.10310}, abstractNote={Fishery‐dependent communities in coastal environments are often vulnerable to hurricanes, but diverse and accessible fisheries may buffer the effects of extreme storms and promote community resilience. We began evaluating this possibility with a qualitative study in the Lowe Sound and Red Bays communities in The Bahamas immediately after the impact of a category 4 hurricane. We interviewed 68 households, asking about the relationships between the storm's impacts and fisheries resources. Lowe Sound respondents described fisheries as natural insurance that provided food and income. Both communities indicated that retaining access to boats was critically important. Respondents most often blamed impacts on low‐elevation geography, followed by religious interpretations. Fishers linked damages with climate change more often than other community members, suggesting that fishers have an experiential knowledge of climate change. We discuss the importance of fisheries as natural insurance, how recovery efforts can strengthen resilience, and potential outreach strategies that incorporate local knowledge.}, number={11}, journal={FISHERIES}, author={Valdez, Rene Xavier and Peterson, Nils and Chen, Alyssa and Steward, Michael and Hannameyer, Katrina and Seebaluck, Hans and Hulthen, Kaj and Langerhans, R. Brian}, year={2019}, month={Nov}, pages={515–523} }
 @article{rius_petry_langerhans_figueiredo-barros_bozelli_honda_nova_araujo_2019, title={Correlates of life-history variation in the livebearing fish Poecilia vivipara (Cyprinodontiformes: Poeciliidae) inhabiting an environmental gradient}, volume={126}, ISSN={["1095-8312"]}, DOI={10.1093/biolinnean/bly208}, abstractNote={1Universidade Estadual Paulista (UNESP), Instituto de Biociências, Av. 24-A, 1515, Rio Claro, 13506900, Brazil 2Universidade Federal do Rio de Janeiro, Instituto de Biodiversidade e Sustentabilidade, Macaé, Brazil 3Department of Biological Sciences and W.M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, NC, USA 4Universidade Federal do Rio de Janeiro, Instituto de Biologia, Rio de Janeiro, Brazil}, number={3}, journal={BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY}, author={Rius, Bianca F. and Petry, Ana Cristina and Langerhans, R. Brian and Figueiredo-Barros, Marcos P. and Bozelli, Reinaldo L. and Honda, Laura K. and Nova, Clarice C. and Araujo, Marcio S.}, year={2019}, month={Mar}, pages={436–446} }
 @article{riesch_martin_diamond_jourdan_plath_langerhans_2018, title={Thermal regime drives a latitudinal gradient in morphology and life history in a livebearing fish}, volume={125}, ISSN={["1095-8312"]}, DOI={10.1093/biolinnean/bly095}, abstractNote={1School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK 2Department of Biology, Case Western Reserve University, Cleveland, OH 44106, USA 3Department of River Ecology and Conservation, Senckenberg Research Institute and Natural History Museum Frankfurt, Gelnhausen, Germany 4College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, PR China 5Department of Biological Sciences & W. M. Keck Center for Behavioral Biology, North Carolina State University, 127 David Clark Labs, Raleigh, NC 27695-7617, USA}, number={1}, journal={BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY}, author={Riesch, Rudiger and Martin, Ryan A. and Diamond, Sarah E. and Jourdan, Jonas and Plath, Martin and Langerhans, R. Brian}, year={2018}, month={Sep}, pages={126–141} }
 @article{araujo_layman_langerhans_2017, title={Body streamlining is related to higher growth in Bahamian mosquitofish}, volume={18}, number={4}, journal={Evolutionary Ecology Research}, author={Araujo, M. S. and Layman, C. A. and Langerhans, R. B.}, year={2017}, pages={383–391} }
 @article{malpica_langerhans_moore_2017, title={Comparing two techniques of analyzing sexual dimorphic Gambusia affinis skeletal structure: Clearing and staining to X-ray}, volume={57}, journal={Integrative and Comparative Biology}, author={Malpica, A. M. and Langerhans, R. B. and Moore, B. C.}, year={2017}, pages={E103–103} }
 @article{shapiro_peterson_stevenson_frew_langerhans_2017, title={Wildlife species preferences differ among children in continental and island locations}, volume={44}, ISSN={0376-8929 1469-4387}, url={http://dx.doi.org/10.1017/S0376892917000133}, DOI={10.1017/s0376892917000133}, abstractNote={SUMMARYEfforts to prioritize wildlife for conservation benefit from an understanding of public preferences for particular species, yet no studies have integrated species preferences with key attributes of the conservation landscape such as whether species occur on islands (where invasive exotics are the primary extinction threat) or continents (where land use change is the primary extinction threat). In this paper, we compare wildlife species preferences among children from a continental location (North Carolina, USA, n = 433) and an island location (Andros Island, The Bahamas, n = 197). Children on the island preferred feral domesticated species and different types of taxa than mainland children, perhaps due to the strongly divergent species richness between the regions (e.g. island children showed greater preferences for invertebrates, lizards and aquatic species). Boys preferred fish, birds and lizards more than girls, whereas girls preferred mammals. The fact that island children showed strong preferences for invasive species suggests challenges for conservation efforts on islands, where controlling invasive exotic species is often of paramount importance, but can conflict with cultural preferences for these same species.}, number={4}, journal={Environmental Conservation}, publisher={Cambridge University Press (CUP)}, author={Shapiro, Hannah G. and Peterson, M. Nils and Stevenson, Kathryn T. and Frew, Kristin N. and Langerhans, R. Brian}, year={2017}, month={Mar}, pages={389–396} }
 @article{langerhans_anderson_heinen-kay_2016, title={Causes and Consequences of Genital Evolution}, volume={56}, ISSN={["1557-7023"]}, DOI={10.1093/icb/icw101}, abstractNote={The study of genital diversity has experienced rapidly burgeoning attention over the past few decades. This research has shown that male genitalia in internally fertilizing animals exhibit remarkably rapid and complex evolution. In recent years, a consensus has emerged that sexual selection is responsible for much of the observed genital diversity, with natural selection largely playing a subsidiary role. Despite enhanced understanding of the key proximate forms of selection responsible for genital evolution, we still have a poor grasp of the broader, ultimate causes and consequences of the striking diversity of genitalia. Here, we highlight three topics that have so far received comparatively little attention and yet could prove critically important. First, we encourage investigation of ecology's direct and indirect roles in genital diversification, as ecological variation can influence selection on genitalia in several ways, perhaps especially by influencing the context of sexual selection. Second, we need more research into the effects of genital divergence on speciation, as genital differences could enhance reproductive isolation through either a lock-and-key process (where selection directly favors reproductive isolation) or as an incidental by-product of divergence. Third, we echo recent calls for increased research on female genitalia, as non-trivial female genital diversity exists, and multiple mechanisms can lead to rapid diversification of female genitalia. For all three topics, we review theory and empirical data, and describe specific research approaches for tackling these questions. We hope this work provides a roadmap toward increased understanding of the causes and consequences of the conspicuous diversity of primary sexual traits, and thus toward new insights into the evolution of complex traits and the phenotypic causes of speciation.}, number={4}, journal={INTEGRATIVE AND COMPARATIVE BIOLOGY}, author={Langerhans, R. Brian and Anderson, Christopher M. and Heinen-Kay, Justa L.}, year={2016}, month={Oct}, pages={741–751} }
 @article{kern_robinson_gass_godwin_langerhans_2016, title={Correlated evolution of personality, morphology and performance}, volume={117}, ISSN={["1095-8282"]}, DOI={10.1016/j.anbehav.2016.04.007}, abstractNote={Evolutionary change in one trait can elicit evolutionary changes in other traits due to genetic correlations. This constrains the independent evolution of traits and can lead to unpredicted ecological and evolutionary outcomes. Animals might frequently exhibit genetic associations among behavioural and morphological-physiological traits, because the physiological mechanisms behind animal personality can have broad multitrait effects and because many selective agents influence the evolution of multiple types of traits. However, we currently know little about genetic correlations between animal personalities and nonbehavioural traits. We tested for associations between personality, morphology and locomotor performance by comparing zebrafish (Danio rerio) collected from the wild and then selectively bred for either a proactive or reactive stress coping style ('bold' or 'shy' phenotypes). Based on adaptive hypotheses of correlational selection in the wild, we predicted that artificial selection for boldness would produce correlated evolutionary responses of larger caudal regions and higher fast-start escape performance (and the opposite for shyness). After four to seven generations, morphology and locomotor performance differed between personality lines: bold zebrafish exhibited a larger caudal region and higher fast-start performance than fish in the shy line, matching predictions. Individual-level phenotypic correlations suggested that pleiotropy or physical gene linkage likely explained the correlated response of locomotor performance, while the correlated response of body shape may have reflected linkage disequilibrium, which is breaking down each generation in the laboratory. Our results indicate that evolution of personality can result in concomitant changes in morphology and whole-organism performance, and vice versa.}, journal={ANIMAL BEHAVIOUR}, author={Kern, Elizabeth M. A. and Robinson, Detric and Gass, Erika and Godwin, John and Langerhans, R. Brian}, year={2016}, month={Jul}, pages={79–86} }
 @article{sukel_langerhans_2016, title={Curious genitalia are signposts of evolution}, volume={229}, number={3062}, journal={New Scientist}, author={Sukel, K. and Langerhans, B.}, year={2016}, pages={32–33} }
 @article{riesch_tobler_lerp_jourdan_doumas_nosil_langerhans_plath_2016, title={Extremophile Poeciliidae: multivariate insights into the complexity of speciation along replicated ecological gradients}, volume={16}, ISSN={["1471-2148"]}, DOI={10.1186/s12862-016-0705-1}, abstractNote={Replicate population pairs that diverge in response to similar selective regimes allow for an investigation of (a) whether phenotypic traits diverge in a similar and predictable fashion, (b) whether there is gradual variation in phenotypic divergence reflecting variation in the strength of natural selection among populations, (c) whether the extent of this divergence is correlated between multiple character suites (i.e., concerted evolution), and (d) whether gradual variation in phenotypic divergence predicts the degree of reproductive isolation, pointing towards a role for adaptation as a driver of (ecological) speciation. Here, we use poeciliid fishes of the genera Gambusia and Poecilia that have repeatedly evolved extremophile lineages able to tolerate high and sustained levels of toxic hydrogen sulfide (H2S) to answer these questions. We investigated evolutionary divergence in response to H2S in Gambusia spp. (and to a lesser extent Poecilia spp.) using a multivariate approach considering the interplay of life history, body shape, and population genetics (nuclear miscrosatellites to infer population genetic differentiation as a proxy for reproductive isolation). We uncovered both shared and unique patterns of evolution: most extremophile Gambusia predictably evolved larger heads and offspring size, matching a priori predictions for adaptation to sulfidic waters, while variation in adult life histories was idiosyncratic. When investigating patterns for both genera (Gambusia and Poecilia), we found that divergence in offspring-related life histories and body shape were positively correlated across populations, but evidence for individual-level associations between the two character suites was limited, suggesting that genetic linkage, developmental interdependencies, or pleiotropic effects do not explain patterns of concerted evolution. We further found that phenotypic divergence was positively correlated with both environmental H2S-concentration and neutral genetic differentiation (a proxy for gene flow). Our results suggest that higher toxicity exerts stronger selection, and that divergent selection appears to constrain gene flow, supporting a scenario of ecological speciation. Nonetheless, progress toward ecological speciation was variable, partially reflecting variation in the strength of divergent selection, highlighting the complexity of selective regimes even in natural systems that are seemingly governed by a single, strong selective agent.}, journal={BMC EVOLUTIONARY BIOLOGY}, author={Riesch, Rudiger and Tobler, Michael and Lerp, Hannes and Jourdan, Jonas and Doumas, Tess and Nosil, Patrik and Langerhans, R. Brian and Plath, Martin}, year={2016}, month={Jun} }
 @article{heinen-kay_schmidt_stafford_costa_peterson_kern_langerhans_2016, title={Predicting multifarious behavioural divergence in the wild}, volume={121}, ISSN={["1095-8282"]}, DOI={10.1016/j.anbehav.2016.08.016}, abstractNote={Many animals show complex behaviours that can have important ecological and evolutionary consequences. Environmental variation can lead to divergent selection that consistently favours particular behaviours in different environments; but how predictably multiple aspects of animal behaviour diverge in response to different environmental conditions remains unclear. We tested whether populations evolving under different levels of predation risk show predictable and repeatable population-level behavioural differences in all five primary components of animal personality: aggression, sociability, boldness, activity and exploration. We formulated and tested a priori predictions of divergence for each behaviour using the adaptive radiation of Bahamas mosquitofish, Gambusia hubbsi (family Poeciliidae), inhabiting vertical water-filled caves (blue holes) where they have evolved for thousands of years in either the presence or absence of predatory fish. Mosquitofish behaviours differed consistently, and largely predictably, between predation regimes: low-predation mosquitofish showed reduced sociability and greater exploration of a novel environment compared to high-predation counterparts. However, some differences were sex dependent: only females showed greater boldness and only males displayed reduced aggressiveness in low-predation populations. Activity levels did not differ between predation regimes. All populations showed a behavioural syndrome characteristic of either proactive or reactive stress-coping styles with regard to exploration. Exploration behavioural syndromes were more similar among populations that evolved in similar predation regimes, regardless of genetic relatedness. Using laboratory-born, high-predation mosquitofish, we confirmed that exploratory behaviours have a genetic basis and show significant within-individual repeatability. Our results suggest that environmental variation, such as chronic predation risk, can lead to repeatable, and often predictable, changes in multifarious animal behaviours, and that various aspects of behaviour can diversify more or less independently of one another. Considering the ecological importance of these behaviours, the ability to forecast behavioural shifts in a rapidly changing world could serve as a valuable conservation tool.}, journal={ANIMAL BEHAVIOUR}, author={Heinen-Kay, Justa L. and Schmidt, Danielle A. and Stafford, A. Tayt and Costa, Michael T. and Peterson, M. Nils and Kern, Elizabeth M. A. and Langerhans, R. Brian}, year={2016}, month={Nov}, pages={3–10} }
 @misc{higham_rogers_langerhans_jamniczky_lauder_stewart_martin_reznick_2016, title={Speciation through the lens of biomechanics: locomotion, prey capture and reproductive isolation}, volume={283}, ISSN={["1471-2954"]}, DOI={10.1098/rspb.2016.1294}, abstractNote={Speciation is a multifaceted process that involves numerous aspects of the biological sciences and occurs for multiple reasons. Ecology plays a major role, including both abiotic and biotic factors. Whether populations experience similar or divergent ecological environments, they often adapt to local conditions through divergence in biomechanical traits. We investigate the role of biomechanics in speciation using fish predator–prey interactions, a primary driver of fitness for both predators and prey. We highlight specific groups of fishes, or specific species, that have been particularly valuable for understanding these dynamic interactions and offer the best opportunities for future studies that link genetic architecture to biomechanics and reproductive isolation (RI). In addition to emphasizing the key biomechanical techniques that will be instrumental, we also propose that the movement towards linking biomechanics and speciation will include (i) establishing the genetic basis of biomechanical traits, (ii) testing whether similar and divergent selection lead to biomechanical divergence, and (iii) testing whether/how biomechanical traits affect RI. Future investigations that examine speciation through the lens of biomechanics will propel our understanding of this key process.}, number={1838}, journal={PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES}, author={Higham, Timothy E. and Rogers, Sean M. and Langerhans, R. Brian and Jamniczky, Heather A. and Lauder, George V. and Stewart, William J. and Martin, Christopher H. and Reznick, David N.}, year={2016}, month={Sep} }
 @article{shapiro_erickson_peterson_frew_stevenson_langerhans_2016, title={Which species to conserve: evaluating children’s species-based conservation priorities}, volume={25}, ISSN={0960-3115 1572-9710}, url={http://dx.doi.org/10.1007/S10531-016-1067-0}, DOI={10.1007/s10531-016-1067-0}, number={3}, journal={Biodiversity and Conservation}, publisher={Springer Science and Business Media LLC}, author={Shapiro, H. G. and Erickson, K. A. and Peterson, M. Nils and Frew, K. N. and Stevenson, K. T. and Langerhans, R. B.}, year={2016}, month={Feb}, pages={539–553} }
 @article{giery_layman_langerhans_2015, title={Anthropogenic ecosystem fragmentation drives shared and unique patterns of sexual signal divergence among three species of Bahamian mosquitofish}, volume={8}, ISSN={["1752-4571"]}, DOI={10.1111/eva.12275}, abstractNote={AbstractWhen confronted with similar environmental challenges, different organisms can exhibit dissimilar phenotypic responses. Therefore, understanding patterns of phenotypic divergence for closely related species requires considering distinct evolutionary histories. Here, we investigated how a common form of human‐induced environmental alteration, habitat fragmentation, may drive phenotypic divergence among three closely related species of Bahamian mosquitofish (Gambusia spp.). Focusing on one phenotypic trait (male coloration), having a priori predictions of divergence, we tested whether populations persisting in fragmented habitats differed from those inhabiting unfragmented habitats and examined the consistency of the pattern across species. Species exhibited both shared and unique patterns of phenotypic divergence between the two types of habitats, with shared patterns representing the stronger effect. For all species, populations in fragmented habitats had fewer dorsal‐fin spots. In contrast, the magnitude and trajectory of divergence in dorsal‐fin color, a sexually selected trait, differed among species. We identified fragmentation‐mediated increased turbidity as a possible driver of these trait shifts. These results suggest that even closely related species can exhibit diverse phenotypic responses when encountering similar human‐mediated selection regimes. This element of unpredictability complicates forecasting the phenotypic responses of wild organisms faced with anthropogenic change – an important component of biological conservation and ecosystem management.}, number={7}, journal={EVOLUTIONARY APPLICATIONS}, author={Giery, Sean T. and Layman, Craig A. and Langerhans, R. Brian}, year={2015}, month={Aug}, pages={679–691} }
 @article{sharpe_langerhans_low-decarie_chapman_2015, title={Little evidence for morphological change in a resilient endemic species following the introduction of a novel predator}, volume={28}, ISSN={["1420-9101"]}, DOI={10.1111/jeb.12720}, abstractNote={AbstractHuman activities, such as species introductions, are dramatically and rapidly altering natural ecological processes and often result in novel selection regimes. To date, we still have a limited understanding of the extent to which such anthropogenic selection may be driving contemporary phenotypic change in natural populations. Here, we test whether the introduction of the piscivorous Nile perch, Lates niloticus, into East Africa's Lake Victoria and nearby lakes coincided with morphological change in one resilient native prey species, the cyprinid fish Rastrineobola argentea. Drawing on prior ecomorphological research, we predicted that this novel predator would select for increased allocation to the caudal region in R. argentea to enhance burst‐swimming performance and hence escape ability. To test this prediction, we compared body morphology of R. argentea across space (nine Ugandan lakes differing in Nile perch invasion history) and through time (before and after establishment of Nile perch in Lake Victoria). Spatial comparisons of contemporary populations only partially supported our predictions, with R. argentea from some invaded lakes having larger caudal regions and smaller heads compared to R. argentea from uninvaded lakes. There was no clear evidence of predator‐associated change in body shape over time in Lake Victoria. We conclude that R. argentea have not responded to the presence of Nile perch with consistent morphological changes and that other factors are driving observed patterns of body shape variation in R. argentea.}, number={11}, journal={JOURNAL OF EVOLUTIONARY BIOLOGY}, author={Sharpe, D. M. T. and Langerhans, R. B. and Low-Decarie, E. and Chapman, L. J.}, year={2015}, month={Nov}, pages={2054–2067} }
 @article{okamoto_langerhans_rashid_amarasekare_2015, title={Microevolutionary patterns in the common caiman predict macroevolutionary trends across extant crocodilians}, volume={116}, ISSN={["1095-8312"]}, DOI={10.1111/bij.12641}, abstractNote={Both extinct and extant crocodilians have repeatedly diversified in skull shape along a continuum, from narrow-snouted to broad-snouted phenotypes. These patterns occur with striking regularity, although it is currently unknown whether these trends also apply to microevolutionary divergence during population differentiation or the early stages of speciation. Assessing patterns of intraspecific variation within a single taxon can potentially provide insight into the processes of macroevolutionary differentiation. For example, high levels of intraspecific variation along a narrow-broad axis would be consistent with the view that cranial shapes can show predictable patterns of differentiation on relatively short timescales, and potentially scale up to explain broader macroevolutionary patterns. In the present study, we use geometric morphometric methods to characterize intraspecific cranial shape variation among groups within a single, widely distributed clade, Caiman crocodilus. We show that C. crocodilus skulls vary along a narrow/broad-snouted continuum, with different subspecies strongly clustered at distinct ends of the continuum. We quantitatively compare these microevolutionary trends with patterns of diversity at macroevolutionary scales (among all extant crocodilians). We find that morphological differences among the subspecies of C. crocodilus parallel the patterns of morphological differentiation across extant crocodilians, with the primary axes of morphological diversity being highly correlated across the two scales. We find intraspecific cranial shape variation within C. crocodilus to span variation characterized by more than half of living species. We show the main axis of intraspecific phenotypic variation to align with the principal direction of macroevolutionary diversification in crocodilian cranial shape, suggesting that mechanisms of microevolutionary divergence within species may also explain broader patterns of diversification at higher taxonomic levels.}, number={4}, journal={BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY}, author={Okamoto, Kenichi W. and Langerhans, R. Brian and Rashid, Rezoana and Amarasekare, Priyanga}, year={2015}, month={Dec}, pages={834–846} }
 @article{anderson_langerhans_2015, title={Origins of female genital diversity: Predation risk and lock-and-key explain rapid divergence during an adaptive radiation}, volume={69}, ISSN={["1558-5646"]}, DOI={10.1111/evo.12748}, abstractNote={The study of male genital diversity has long overshadowed evolutionary inquiry of female genitalia, despite its nontrivial diversity. Here, we identify four nonmutually exclusive mechanisms that could lead to genital divergence in females, and potentially generate patterns of correlated male–female genital evolution: (1) ecological variation alters the context of sexual selection (“ecology hypothesis”), (2) sexually antagonistic selection (“sexual‐conflict hypothesis”), (3) female preferences for male genitalia mediated by female genital traits (“female‐choice hypothesis”), and (4) selection against inter‐population mating (“lock‐and‐key hypothesis”). We performed an empirical investigation of all four hypotheses using the model system of Bahamas mosquitofish inhabiting blue holes that vary in predation risk. We found unequivocal support for the ecology hypothesis, with females exhibiting a smaller genital opening in blue holes containing piscivorous fish. This is consistent with stronger postmating female choice/conflict when predators are present, but greater premating female choice in their absence. Our results additionally supported the lock‐and‐key hypothesis, uncovering a pattern of reproductive character displacement for genital shape. We found no support for the sexual conflict or female choice hypotheses. Our results demonstrate a strong role for ecology in generating female genital diversity, and suggest that lock‐and‐key may provide a viable cause of female genital diversification.}, number={9}, journal={EVOLUTION}, author={Anderson, Christopher M. and Langerhans, R. Brian}, year={2015}, month={Sep}, pages={2452–2467} }
 @article{martin_mcgee_langerhans_2015, title={Predicting ecological and phenotypic differentiation in the wild: a case of piscivorous fish in a fishless environment}, volume={114}, ISSN={["1095-8312"]}, DOI={10.1111/bij.12449}, abstractNote={Environmental variation drives ecological and phenotypic change. How predictable is differentiation in response to environmental change? Answering this question requires the development and testing of multifarious a priori predictions in natural systems. We employ this approach using Gobiomorus dormitor populations that have colonized inland blue holes differing in the availability of fish prey. We evaluated predictions of differences in demographics, habitat use, diet, locomotor and trophic morphology, and feeding kinematics and performance between G. dormitor populations inhabiting blue holes with and without fish prey. Populations of G. dormitor independently diverged between prey regimes, with broad agreement between observed differences and a priori predictions. For example, in populations lacking fish prey, we observed male-biased sex ratios, a greater use of shallow-water habitat, and larger population diet breadths as a result of greater individual diet specialization. Furthermore, we found predictable differences in body shape, mouth morphology, suction generation capacity, strike kinematics, and feeding performance on different prey types, consistent with the adaptation of G. dormitor to piscivory when coexisting with fish prey and to feeding on small invertebrates in their absence. The results of the present study suggest great potential in our ability to predict population responses to changing environments, which is an increasingly important capability in a human-dominated, ever-changing world. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114, 588–607.}, number={3}, journal={BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY}, author={Martin, Ryan A. and McGee, Matthew D. and Langerhans, R. Brian}, year={2015}, month={Mar}, pages={588–607} }
 @article{riesch_easter_layman_langerhans_2015, title={Rapid human-induced divergence of life-history strategies in Bahamian livebearing fishes (family Poeciliidae)}, volume={84}, ISSN={["1365-2656"]}, DOI={10.1111/1365-2656.12425}, abstractNote={Summary


Human‐induced rapid environmental change (HIREC) can have dramatic impacts on ecosystems, leading to rapid trait changes in some organisms and extinction in others. Such changes in traits signify that human actions can lead to cases of increased phenotypic diversity and consequently can strongly impact population‐, community‐ and ecosystem‐level dynamics.

Here, we examine whether the ecological consequences of habitat fragmentation have led to changes in the life histories of three native species of mosquitofish (Gambusia spp.) inhabiting tidal creeks on six different Bahamian islands. We address two important questions: (i) How predictable and parallel are life‐history changes in response to HIREC across islands and species, and (ii) what is the relative importance of shared (i.e. parallel) responses to fragmentation, differences between species or islands and species‐ or island‐specific responses to fragmentation?

Phenotypic differences between fragmentation regimes were as great or greater than differences between species or islands. While some adult life histories (lean weight and fat content) showed strong, shared responses to fragmentation, offspring‐related life histories (embryo fat and fecundity) exhibited idiosyncratic, island‐specific responses. While shared responses to fragmentation appeared largely driven by a reduction in piscivorous fish density, increased conspecific density and changes in salinity, we found some evidence that among‐population variation in male reproductive investment and embryo fat content may have arisen via variation in conspecific density.

Our results suggest that phenotypic responses to HIREC can be complex, with the predictability of response varying across traits. We therefore emphasize the need for more theoretical and empirical work to better understand the predictability of phenotypic responses to human‐induced disturbances.

}, number={6}, journal={JOURNAL OF ANIMAL ECOLOGY}, author={Riesch, Ruediger and Easter, Tara and Layman, Craig A. and Langerhans, Randall Brian}, year={2015}, month={Nov}, pages={1732–1743} }
 @article{hayes_peterson_heinen-kay_langerhans_2015, title={Tourism-related drivers of support for protection of fisheries resources on Andros Island, The Bahamas}, volume={106}, ISSN={0964-5691}, url={http://dx.doi.org/10.1016/J.OCECOAMAN.2015.01.007}, DOI={10.1016/j.ocecoaman.2015.01.007}, abstractNote={Fisheries resources in the Caribbean suffer intense pressure from overharvesting. Some of the most valuable fisheries in The Bahamas, such as queen conch (Strombus gigas), spiny lobster (Panulirus argus), and Nassau grouper (Epinephelus striatus), are overexploited and require additional protection. Despite these pressures, we currently know very little about the factors that underlie local residents' support for such protection. We interviewed residents of Andros Island, The Bahamas to evaluate how perception of environmental impacts of tourism, perception of benefits of tourism for their quality of life, income generation from tourism, and education level influenced their willingness to support additional protection of marine resources in the face of a growing tourism industry. We found that respondents supporting additional marine resource protection tended to perceive tourism as having negative impacts on marine resources and neutral to positive effects on their family's quality of life. Attending at least some college also positively influenced support for marine resource protection, although whether residents sold natural products to tourists did not appear to influence their stance on marine resource protection. Our results suggest education in a broad sense, and particularly education highlighting how tourism can both positively affect human well-being and harm marine resources, will promote public support for marine resource protection.}, journal={Ocean & Coastal Management}, publisher={Elsevier BV}, author={Hayes, Maureen C. and Peterson, M. Nils and Heinen-Kay, Justa L. and Langerhans, R. Brian}, year={2015}, month={Mar}, pages={118–123} }
 @article{heinen-kay_morris_ryan_byerley_venezia_peterson_langerhans_2015, title={A trade-off between natural and sexual selection underlies diversification of a sexual signal}, volume={26}, ISSN={["1465-7279"]}, DOI={10.1093/beheco/aru228}, abstractNote={A longstanding hypothesis in evolutionary biology is that trade-offs between natural and sexual selection often underlie the diversification of sexual signals in the wild. A classic example of this "selection trade-off hypothesis" proposes that males evolve elaborate and conspicuous ornamentation in low-risk environments where female preferences dominate selection on sexual traits, but they evolve muted and relatively cryptic sexual traits in high-risk environments where selection from predators acts against conspicuous sexual traits and female preferences potentially weaken or reverse. However, little direct empirical evidence supports this notion. Using the model system of Bahamas mosquitofish (Gambusia hubbsi)—where males have recently evolved greater orange coloration in their dorsal fins in blue holes lacking predatory fish relative to populations with fish predators—we tested this hypothesis using fish replicas differing only in dorsal-fin color. Specifically, we employed plastic fish models in a combination of field and lab experiments to directly examine conspicuity to predators and female preferences for dorsal-fin color. We found that orange-shifted dorsal fins resembling the color exhibited in predator-free populations appeared more conspicuous to predatory bigmouth sleepers (Gobiomorus dormitor) that are evolutionarily naive to mosquitofish. Wild-caught female mosquitofish preferred the orange-shifted dorsal-fin model during dichotomous choice tests; evolutionary history with predators did not affect female preferences. Similar mate-choice trials with lab-born virgin females also found preferences for the orange-shifted dorsal-fin model and revealed significant genetic variation for female preferences. Our study provides direct empirical evidence documenting a trade-off between natural and sexual selection in a colorful sexual signal.}, number={2}, journal={BEHAVIORAL ECOLOGY}, author={Heinen-Kay, Justa L. and Morris, Kirstin E. and Ryan, Nicole A. and Byerley, Samantha L. and Venezia, Rebecca E. and Peterson, M. Nils and Langerhans, R. Brian}, year={2015}, pages={533–542} }
 @article{chacin_giery_yeager_layman_brian langerhans_2014, title={Does hydrological fragmentation affect coastal bird communities? A study from Abaco Island, The Bahamas}, volume={23}, ISSN={0923-4861 1572-9834}, url={http://dx.doi.org/10.1007/S11273-014-9389-8}, DOI={10.1007/s11273-014-9389-8}, number={3}, journal={Wetlands Ecology and Management}, publisher={Springer Science and Business Media LLC}, author={Chacin, Dinorah H. and Giery, Sean T. and Yeager, Lauren A. and Layman, Craig A. and Brian Langerhans, R.}, year={2014}, month={Oct}, pages={551–557} }
 @misc{wellborn_langerhans_2015, title={Ecological opportunity and the adaptive diversification of lineages}, volume={5}, ISSN={["2045-7758"]}, DOI={10.1002/ece3.1347}, abstractNote={AbstractThe tenet that ecological opportunity drives adaptive diversification has been central to theories of speciation since Darwin, yet no widely accepted definition or mechanistic framework for the concept currently exists. We propose a definition for ecological opportunity that provides an explicit mechanism for its action. In our formulation, ecological opportunity refers to environmental conditions that both permit the persistence of a lineage within a community, as well as generate divergent natural selection within that lineage. Thus, ecological opportunity arises from two fundamental elements: (1) niche availability, the ability of a population with a phenotype previously absent from a community to persist within that community and (2) niche discordance, the diversifying selection generated by the adaptive mismatch between a population's niche‐related traits and the newly encountered ecological conditions. Evolutionary response to ecological opportunity is primarily governed by (1) spatiotemporal structure of ecological opportunity, which influences dynamics of selection and development of reproductive isolation and (2) diversification potential, the biological properties of a lineage that determine its capacity to diversify. Diversification under ecological opportunity proceeds as an increase in niche breadth, development of intraspecific ecotypes, speciation, and additional cycles of diversification that may themselves be triggered by speciation. Extensive ecological opportunity may exist in depauperate communities, but it is unclear whether ecological opportunity abates in species‐rich communities. Because ecological opportunity should generally increase during times of rapid and multifarious environmental change, human activities may currently be generating elevated ecological opportunity – but so far little work has directly addressed this topic. Our framework highlights the need for greater synthesis of community ecology and evolutionary biology, unifying the four major components of the concept of ecological opportunity.}, number={1}, journal={ECOLOGY AND EVOLUTION}, author={Wellborn, Gary A. and Langerhans, R. Brian}, year={2015}, month={Jan}, pages={176–195} }
 @article{araújo_langerhans_giery_layman_2014, title={Ecosystem fragmentation drives increased diet variation in an endemic livebearing fish of the Bahamas}, volume={4}, ISSN={2045-7758}, url={http://dx.doi.org/10.1002/ECE3.1140}, DOI={10.1002/ece3.1140}, abstractNote={AbstractOne consequence of human‐driven habitat degradation in general, and habitat fragmentation in particular, is loss of biodiversity. An often‐underappreciated aspect of habitat fragmentation relates to changes in the ecology of species that persist in altered habitats. In Bahamian wetlands, ecosystem fragmentation causes disruption of hydrological connectivity between inland fragmented wetlands and adjacent marine areas, with the consequent loss of marine piscivores from fragmented sections. We took advantage of this environmental gradient to investigate effects of ecosystem fragmentation on patterns of resource use in the livebearing fish Gambusia hubbsi (Family Poeciliidae), using both population‐ and individual‐level perspectives. We show that fragmentation‐induced release from predation led to increased G. hubbsi population densities, which consequently led to lower mean growth rates, likely as a result of higher intraspecific competition for food. This was accompanied by a broadening of dietary niches via increased interindividual diet variation, suggesting a negative effect of predation and a positive effect of intraspecific competition on the degree of diet variation in natural populations. Our results therefore indicate that habitat fragmentation can greatly impact the ecology of resilient populations, with potentially important ecological and evolutionary implications.}, number={16}, journal={Ecology and Evolution}, publisher={Wiley}, author={Araújo, Márcio S. and Langerhans, R. Brian and Giery, Sean T. and Layman, Craig A.}, year={2014}, month={Jul}, pages={3298–3308} }
 @article{heinen-kay_noel_layman_langerhans_2014, title={Human-caused habitat fragmentation can drive rapid divergence of male genitalia}, volume={7}, ISSN={["1752-4571"]}, DOI={10.1111/eva.12223}, abstractNote={AbstractThe aim of this study rests on three premises: (i) humans are altering ecosystems worldwide, (ii) environmental variation often influences the strength and nature of sexual selection, and (iii) sexual selection is largely responsible for rapid and divergent evolution of male genitalia. While each of these assertions has strong empirical support, no study has yet investigated their logical conclusion that human impacts on the environment might commonly drive rapid diversification of male genital morphology. We tested whether anthropogenic habitat fragmentation has resulted in rapid changes in the size, allometry, shape, and meristics of male genitalia in three native species of livebearing fishes (genus: Gambusia) inhabiting tidal creeks across six Bahamian islands. We found that genital shape and allometry consistently and repeatedly diverged in fragmented systems across all species and islands. Using a model selection framework, we identified three ecological consequences of fragmentation that apparently underlie observed morphological patterns: decreased predatory fish density, increased conspecific density, and reduced salinity. Our results demonstrate that human modifications to the environment can drive rapid and predictable divergence in male genitalia. Given the ubiquity of anthropogenic impacts on the environment, future research should evaluate the generality of our findings and potential consequences for reproductive isolation.}, number={10}, journal={EVOLUTIONARY APPLICATIONS}, author={Heinen-Kay, Justa L. and Noel, Holly G. and Layman, Craig A. and Langerhans, R. Brian}, year={2014}, month={Dec}, pages={1252–1267} }
 @article{sanger_seav_tokita_langerhans_ross_losos_abzhanov_2014, title={The oestrogen pathway underlies the evolution of exaggerated male cranial shapes in Anolis lizards}, volume={281}, ISSN={["1471-2954"]}, DOI={10.1098/rspb.2014.0329}, abstractNote={
            Sexual dimorphisms vary widely among species. This variation must arise through sex-specific evolutionary modifications to developmental processes.
            Anolis
            lizards vary extensively in their expression of cranial dimorphism. Compared with other
            Anolis
            species, members of the
            carolinensis
            clade have evolved relatively high levels of cranial dimorphism; males of this clade have exceptionally long faces relative to conspecific females. Developmentally, this facial length dimorphism arises through an evolutionarily novel, clade-specific strategy. Our analyses herein reveal that sex-specific regulation of the oestrogen pathway underlies evolution of this exaggerated male phenotype, rather than the androgen or insulin growth factor pathways that have long been considered the primary regulators of male-biased dimorphism among vertebrates. Our results suggest greater intricacy in the genetic mechanisms that underlie sexual dimorphisms than previously appreciated.
          }, number={1784}, journal={PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES}, author={Sanger, Thomas J. and Seav, Susan M. and Tokita, Masayoshi and Langerhans, R. Brian and Ross, Lela M. and Losos, Jonathan B. and Abzhanov, Arhat}, year={2014}, month={Jun} }
 @article{riesch_plath_schlupp_tobler_langerhans_2014, title={Colonisation of toxic environments drives predictable life-history evolution in livebearing fishes (Poeciliidae)}, volume={17}, ISSN={["1461-0248"]}, DOI={10.1111/ele.12209}, abstractNote={AbstractNew World livebearing fishes (family Poeciliidae) have repeatedly colonised toxic, hydrogen sulphide‐rich waters across their natural distribution. Physiological considerations and life‐history theory predict that these adverse conditions should favour the evolution of larger offspring. Here, we examined nine poeciliid species that independently colonised toxic environments, and show that these fishes have indeed repeatedly evolved much larger offspring size at birth in sulphidic waters, thus uncovering a widespread pattern of predictable evolution. However, a second pattern, only indirectly predicted by theory, proved additionally common: a reduction in the number of offspring carried per clutch (i.e. lower fecundity). Our analyses reveal that this secondary pattern represents a mere consequence of a classic life‐history trade‐off combined with strong selection on offspring size alone. With such strong natural selection in extreme environments, extremophile organisms may commonly exhibit multivariate phenotypic shifts even though not all diverging traits necessarily represent adaptations to the extreme conditions.}, number={1}, journal={ECOLOGY LETTERS}, author={Riesch, Ruediger and Plath, Martin and Schlupp, Ingo and Tobler, Michael and Langerhans, R. Brian}, year={2014}, month={Jan}, pages={65–71} }
 @article{martin_riesch_heinen-kay_langerhans_2014, title={EVOLUTION OF MALE COLORATION DURING A POST-PLEISTOCENE RADIATION OF BAHAMAS MOSQUITOFISH (GAMBUSIA HUBBSI)}, volume={68}, ISSN={["1558-5646"]}, DOI={10.1111/evo.12277}, abstractNote={Sexual signal evolution can be complex because multiple factors influence the production, transmission, and reception of sexual signals, as well as receivers’ responses to them. To grasp the relative importance of these factors in generating signal diversity, we must simultaneously investigate multiple selective agents and signaling traits within a natural system. We use the model system of the radiation of Bahamas mosquitofish (Gambusia hubbsi) inhabiting blue holes to test the effects of resource availability, male body size and other life‐history traits, key aspects of the transmission environment, sex ratio, and predation risk on variation in multiple male color traits. Consistent with previous work examining other traits in this system, several color traits have repeatedly diverged between predation regimes, exhibiting greater elaboration in the absence of predators. However, other factors proved influential as well, with variation in resource levels, body size, relative testes size, and background water color being especially important for several color traits. For one prominent signaling trait, orange dorsal fins, we further confirmed a genetic basis underlying population differences using a laboratory common‐garden experiment. We illustrate a promising approach for gaining a detailed understanding of the many contributing factors in the evolution of multivariate sexual signals.}, number={2}, journal={EVOLUTION}, author={Martin, Ryan A. and Riesch, Ruediger and Heinen-Kay, Justa L. and Langerhans, R. Brian}, year={2014}, month={Feb}, pages={397–411} }
 @article{heinen_coco_marcuard_white_peterson_martin_langerhans_2013, title={Environmental drivers of demographics, habitat use, and behavior during a post-Pleistocene radiation of Bahamas mosquitofish (Gambusia hubbsi)}, volume={27}, ISSN={0269-7653 1573-8477}, url={http://dx.doi.org/10.1007/S10682-012-9627-6}, DOI={10.1007/s10682-012-9627-6}, number={5}, journal={Evolutionary Ecology}, publisher={Springer Science and Business Media LLC}, author={Heinen, Justa L. and Coco, Matthew W. and Marcuard, Maurice S. and White, Danielle N. and Peterson, M. Nils and Martin, Ryan A. and Langerhans, R. Brian}, year={2013}, month={Jan}, pages={971–991} }
 @article{vega-trejo_jaime zuniga-vega_langerhans_2014, title={Morphological differentiation among populations of Rhinella marina (Amphibia: Anura) in western Mexico}, volume={28}, ISSN={["1573-8477"]}, DOI={10.1007/s10682-013-9667-6}, number={1}, journal={EVOLUTIONARY ECOLOGY}, author={Vega-Trejo, Regina and Jaime Zuniga-Vega, J. and Langerhans, R. Brian}, year={2014}, month={Jan}, pages={69–88} }
 @article{langerhans_makowicz_2013, title={Sexual selection paves the road to sexual isolation during ecological speciation}, volume={15}, number={6}, journal={Evolutionary Ecology Research}, author={Langerhans, R. B. and Makowicz, A. M.}, year={2013}, pages={633–651} }
 @article{langerhans_riesch_2013, title={Speciation by selection: A framework for understanding ecology's role in speciation}, volume={59}, ISSN={["2396-9814"]}, DOI={10.1093/czoolo/59.1.31}, abstractNote={Abstract
               Speciation research during the last several decades has confirmed that natural selection frequently drives the generation of new species. But how does this process generally unfold in nature? We argue that answering this question requires a clearer conceptual framework for understanding selection’s role in speciation. We present a unified framework of speciation, providing mechanistic descriptions of fundamentally distinct routes to speciation, and how these may interact during lineage splitting. Two major categories are recognized: reproductive isolation resulting from (1) responses to selection, “speciation by selection,” or (2) non-selective processes, “speciation without selection.” Speciation by selection can occur via three mechanisms: (1) similar selection, (2) divergent selection, and (3) reinforcement selection. Understanding ecology’s role in speciation requires uncovering how these three mechanisms contribute to reproductive isolation, and their relative importance compared to non-selective processes, because all three mechanisms can occur side-by-side during speciation. To accomplish this, we highlight examination of groups of organisms inhabiting replicated environmental gradients. This scenario is common in nature, and a large literature illustrates that both parallel and non-parallel responses to similar environments are widespread, and each can result in speciation. This recognition reveals four general pathways of speciation by similar or divergent selection—parallel and nonparallel responses to similar and divergent selection. Altogether, we present a more precise framework for speciation research, draw attention to some under-recognized features of speciation, emphasize the multidimensionality of speciation, reveal limitations of some previous tests and descriptions of speciation mechanisms, and point to a number of directions for future investigation.}, number={1}, journal={CURRENT ZOOLOGY}, author={Langerhans, R. Brian and Riesch, Ruediger}, year={2013}, pages={31–52} }
 @article{langerhans_gifford_dominguez-dominguez_garcia-bedoya_dewitt_2012, title={Gambusia quadruncus (Cyprinodontiformes: Poeciliidae): a new species of mosquitofish from east-central Mexico}, volume={81}, ISSN={["0022-1112"]}, DOI={10.1111/j.1095-8649.2012.03397.x}, abstractNote={Gambusia quadruncus n. sp., the llanos mosquitofish, is described from east‐central México. The region inhabited by the species represents a hotspot of diversity of Gambusia, and G. quadruncus sometimes coexists with at least three congeners. The species differs from its closest relative, Gambusia affinis, in several characteristics with plausible effects on reproductive isolation, e.g. body size, body and fin morphology, male genital morphology (distal tip of gonopodium) and female anal spot morphology (colouration near the urogenital sinus). Moreover, combined analysis of mitochondrial and nuclear gene sequence data (c. 2158 total base pairs) indicates reciprocal monophyly of G. quadruncus and its sister species G. affinis, with levels of genetic divergence suggesting the two species diverged from one another over a million years ago. The origin of G. quadruncus may reflect a vicariant event associated with Pliocene orogenesis in the Tamaulipas Arch and a frontal section of the Sierra Madre Oriental (Lleran Mesas). Gambusia quadruncus inhabits a variety of freshwater habitats across several river drainages, with its range spanning at least 350 km from north to south, covering over 25 000 km2. A key to aid identification of the species is provided.}, number={5}, journal={JOURNAL OF FISH BIOLOGY}, author={Langerhans, R. B. and Gifford, M. E. and Dominguez-Dominguez, O. and Garcia-Bedoya, D. and DeWitt, T. J.}, year={2012}, month={Oct}, pages={1514–1539} }
 @article{riesch_martin_langerhans_2013, title={Predation's Role in Life-History Evolution of a Livebearing Fish and a Test of the Trexler-DeAngelis Model of Maternal Provisioning}, volume={181}, ISSN={["1537-5323"]}, DOI={10.1086/668597}, abstractNote={Populations experiencing consistent differences in predation risk and resource availability are expected to follow divergent evolutionary trajectories. For example, live-history theory makes specific predictions for how predation should drive life-history evolution, and according to the Trexler-DeAngelis model for the evolution of matrotrophy, postfertilization maternal provisioning is most likely to evolve in environments with consistent, high levels of resource availability. Using the model system of Bahamas mosquitofish (Gambusia hubbsi) inhabiting blue holes with and without the piscivorous bigmouth sleeper (Gobiomorus dormitor), we provide some of the strongest tests of these predictions to date, as resource availability does not covary with predation regime in this system, and we examine numerous (14) isolated natural populations. We found clear evidence for the expected life-history divergence between predation regimes and empirical support of the Trexler-DeAngelis model. Moreover, based on molecular and lab-rearing data, our study offers strong evidence for convergent evolution of similar life histories in similar predation regimes, largely matching previous phenotypic patterns observed in other poeciliid lineages (Brachyrhaphis spp., Poecilia reticulata), and further supports the notion that matrotrophy is most likely to evolve in stable high-resource environments.}, number={1}, journal={AMERICAN NATURALIST}, author={Riesch, Ruediger and Martin, Ryan A. and Langerhans, R. Brian}, year={2013}, month={Jan}, pages={78–93} }
 @article{riesch_schlupp_langerhans_plath_2011, title={Shared and Unique Patterns of Embryo Development in Extremophile Poeciliids}, volume={6}, ISSN={["1932-6203"]}, DOI={10.1371/journal.pone.0027377}, abstractNote={Background Closely related lineages of livebearing fishes have independently adapted to two extreme environmental factors: toxic hydrogen sulphide (H2S) and perpetual darkness. Previous work has demonstrated in adult specimens that fish from these extreme habitats convergently evolved drastically increased head and offspring size, while cave fish are further characterized by reduced pigmentation and eye size. Here, we traced the development of these (and other) divergent traits in embryos of Poecilia mexicana from benign surface habitats (“surface mollies”) and a sulphidic cave (“cave mollies”), as well as in embryos of the sister taxon, Poecilia sulphuraria from a sulphidic surface spring (“sulphur mollies”). We asked at which points during development changes in the timing of the involved processes (i.e., heterochrony) would be detectible. Methods and Results Data were extracted from digital photographs taken of representative embryos for each stage of development and each type of molly. Embryo mass decreased in convergent fashion, but we found patterns of embryonic fat content and ovum/embryo diameter to be divergent among all three types of mollies. The intensity of yellow colouration of the yolk (a proxy for carotenoid content) was significantly lower in cave mollies throughout development. Moreover, while relative head size decreased through development in surface mollies, it increased in both types of extremophile mollies, and eye growth was arrested in mid-stage embryos of cave mollies but not in surface or sulphur mollies. Conclusion Our results clearly demonstrate that even among sister taxa convergence in phenotypic traits is not always achieved by the same processes during embryo development. Furthermore, teleost development is crucially dependent on sufficient carotenoid stores in the yolk, and so we discuss how the apparent ability of cave mollies to overcome this carotenoid-dependency may represent another potential mechanism explaining the lack of gene flow between surface and cave mollies.}, number={11}, journal={PLOS ONE}, author={Riesch, Ruediger and Schlupp, Ingo and Langerhans, R. Brian and Plath, Martin}, year={2011}, month={Nov} }
 @article{langerhans_2010, title={Predicting Evolution with Generalized Models of Divergent Selection: A Case Study with Poeciliid Fish}, volume={50}, ISSN={["1557-7023"]}, DOI={10.1093/icb/icq117}, abstractNote={Over the past century and half since the process of natural selection was first described, one enduring question has captivated many, "how predictable is evolution?" Because natural selection comprises deterministic components, the course of evolution may exhibit some level of predictability across organismal groups. Here, I provide an early appraisal of the utility of one particular approach to understanding the predictability of evolution: generalized models of divergent selection (GMDS). The GMDS approach is meant to provide a unifying framework for the science of evolutionary prediction, offering a means of better understanding the causes and consequences of phenotypic and genetic evolution. I describe and test a GMDS centered on the evolution of body shape, size of the gonopodium (sperm-transfer organ), steady-swimming abilities, fast-start swimming performance, and reproductive isolation between populations in Gambusia fishes (Family Poeciliidae). The GMDS produced some accurate evolutionary predictions in Gambusia, identifying variation in intensity of predation by piscivorous fish as a major factor driving repeatable and predictable phenotypic divergence, and apparently playing a key role in promoting ecological speciation. Moreover, the model's applicability seems quite general, as patterns of differentiation in body shape between predator regimes in many disparate fishes match the model's predictions. The fact that such a simple model could yield accurate evolutionary predictions in distantly related fishes inhabiting different geographic regions and types of habitat, and experiencing different predator species, suggests that the model pinpointed a causal factor underlying major, shared patterns of diversification. The GMDS approach appears to represent a promising method of addressing the predictability of evolution and identifying environmental factors responsible for driving major patterns of replicated evolution.}, number={6}, journal={INTEGRATIVE AND COMPARATIVE BIOLOGY}, author={Langerhans, R. Brian}, year={2010}, month={Dec}, pages={1167–1184} }
 @article{allan_langerhans_ryberg_landesman_griffin_katz_oberle_schutzenhofer_smyth_de st. maurice_et al._2008, title={Ecological correlates of risk and incidence of West Nile virus in the United States}, volume={158}, ISSN={0029-8549 1432-1939}, url={http://dx.doi.org/10.1007/S00442-008-1169-9}, DOI={10.1007/S00442-008-1169-9}, abstractNote={West Nile virus, which was recently introduced to North America, is a mosquito-borne pathogen that infects a wide range of vertebrate hosts, including humans. Several species of birds appear to be the primary reservoir hosts, whereas other bird species, as well as other vertebrate species, can be infected but are less competent reservoirs. One hypothesis regarding the transmission dynamics of West Nile virus suggests that high bird diversity reduces West Nile virus transmission because mosquito blood-meals are distributed across a wide range of bird species, many of which have low reservoir competence. One mechanism by which this hypothesis can operate is that high-diversity bird communities might have lower community-competence, defined as the sum of the product of each species’ abundance and its reservoir competence index value. Additional hypotheses posit that West Nile virus transmission will be reduced when either: (1) abundance of mosquito vectors is low; or (2) human population density is low. We assessed these hypotheses at two spatial scales: a regional scale near Saint Louis, MO, and a national scale (continental USA). We found that prevalence of West Nile virus infection in mosquito vectors and in humans increased with decreasing bird diversity and with increasing reservoir competence of the bird community. Our results suggest that conservation of avian diversity might help ameliorate the current West Nile virus epidemic in the USA}, number={4}, journal={Oecologia}, publisher={Springer Science and Business Media LLC}, author={Allan, Brian F. and Langerhans, R. Brian and Ryberg, Wade A. and Landesman, William J. and Griffin, Nicholas W. and Katz, Rachael S. and Oberle, Brad J. and Schutzenhofer, Michele R. and Smyth, Kristina N. and de St. Maurice, Annabelle and et al.}, year={2008}, month={Oct}, pages={699–708} }
 @article{langerhans_layman_dewitt_2005, title={Male genital size reflects a tradeoff between attracting mates and avoiding predators in two live-bearing fish species}, volume={102}, ISSN={0027-8424 1091-6490}, url={http://dx.doi.org/10.1073/pnas.0500935102}, DOI={10.1073/pnas.0500935102}, abstractNote={
            Male genitalia may experience more rapid, divergent evolution than any other animal character, but why? Research during the past several decades has culminated in the view that genital diversification primarily results from postmating sexual selection (e.g., sperm competition or cryptic female choice). However, the potential roles of premating sexual selection (e.g., mate choice) and natural selection have received little attention. We examined the possible importance of these mechanisms by investigating divergence in male genitalia among populations differing in predator regime for two species of live-bearing fish (
            Gambusia affinis
            in Texas and
            Gambusia hubbsi
            in The Bahamas). When controlled for body size, males exhibited a larger gonopodium (sperm-transfer organ) in predator-free environments than in predatory environments, a trend that persisted across space (multiple populations), time (multiple years), and species. By conducting laboratory experiments with
            G. affinis
            , we found that premating sexual selection seems to favor larger male genitalia (females exhibited mating preference for males having larger gonopodia), but natural selection in the presence of predatory fishes seems to favor reduced genital size (larger gonopodium size was associated with reduced burst-swimming performance, an important antipredator behavior). Although postmating sexual selection is widely presumed to be the most important mechanism driving genital diversification, these findings suggest that alternative mechanisms, particularly for organisms that cannot retract their genitalia, may also prove important.
          }, number={21}, journal={Proceedings of the National Academy of Sciences}, publisher={Proceedings of the National Academy of Sciences}, author={Langerhans, R. B. and Layman, C. A. and DeWitt, T. J.}, year={2005}, month={May}, pages={7618–7623} }