TY - JOUR TI - Optimal defence theory and flower petal colour predict variation in the secondary chemistry of wild radish AU - Strauss, Sharon Y. AU - Irwin, Rebecca E. AU - Lambrix, Virginia M. T2 - Journal of Ecology AB - Summary 1The presence, concentration and composition of plant secondary compounds, which confer plant resistance to herbivores and pathogens, vary greatly both within and among individuals. Optimal defence theory predicts that plant tissues most closely tied to plant fitness should be most defended at the constitutive level, and that more expendable tissues should be inducible with damage. 2We examined variation in glucosinolate content between leaves and petals, as well as among four petal colour morphs of wild radish, Raphanus sativus . We predicted greater levels of constitutive defences in petals, and greater inducibility of glucosinolates in leaves, based on previous studies that could relate leaves and petals to plant fitness. 3While, overall, optimal defence predictions were supported, individual glucosinolates differed in both their degree of inducibility as well as in their distribution between tissue types. 4Petal colour variants differed in their induced responses to damage, but not in their constitutive levels of compounds. Yellow and white morphs, which are preferred by the dominant bee pollinators as well as by herbivores, were generally less inducible than anthocynanin-containing pink and bronze petal morphs. 5Pleiotropic effects between petal colour and defence loci, or tight linkage between these loci, may allow pollinators to maintain variation in secondary chemistry, as well as allow herbivores to influence colour morph fitness and prevalence. DA - 2004/1/7/ PY - 2004/1/7/ DO - 10.1111/j.1365-2745.2004.00843.x VL - 92 IS - 1 SP - 132-141 J2 - Journal of Ecology LA - en OP - SN - 0022-0477 1365-2745 UR - http://dx.doi.org/10.1111/j.1365-2745.2004.00843.x DB - Crossref ER - TY - JOUR TI - Community and Evolutionary Ecology of Nectar1 AU - Irwin, R. E. AU - Adler, L. S. AU - Agrawal, A. A. T2 - Ecology AB - EcologyVolume 85, Issue 6 p. 1477-1478 Special Features Community and Evolutionary Ecology of Nectar† R. E. Irwin, R. E. Irwin Guest Editor University of GeorgiaSearch for more papers by this authorL. S. Adler, L. S. Adler Guest Editor Virginia Tech UniversitySearch for more papers by this authorA. A. Agrawal, A. A. Agrawal Special Features Editor University of TorontoSearch for more papers by this author R. E. Irwin, R. E. Irwin Guest Editor University of GeorgiaSearch for more papers by this authorL. S. Adler, L. S. Adler Guest Editor Virginia Tech UniversitySearch for more papers by this authorA. A. Agrawal, A. A. Agrawal Special Features Editor University of TorontoSearch for more papers by this author First published: 01 June 2004 https://doi.org/10.1890/03-0717Citations: 6Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article.Citing Literature Volume85, Issue6June 2004Pages 1477-1478 RelatedInformation DA - 2004/6// PY - 2004/6// DO - 10.1890/03-0717 VL - 85 IS - 6 SP - 1477-1478 J2 - Ecology LA - en OP - SN - 0012-9658 UR - http://dx.doi.org/10.1890/03-0717 DB - Crossref ER - TY - JOUR TI - Direct and indirect effects of pollinators and seed predators to selection on plant and floral traits AU - Cariveau, Daniel AU - Irwin, Rebecca E. AU - Brody, Alison K. AU - Garcia‐Mayeya, Lucero Sevillano AU - Von Der Ohe, Andrea T2 - Oikos AB - Although flowering traits are often assumed to be under strong selection by pollinators, significant variation in such traits remains the norm for most plant species. Thus, it is likely that the interactions among plants, mutualists, and other selective agents, such as antagonists, ultimately shape the evolution of floral and flowering traits. We examined the importance of pollination vs pre‐dispersal seed predation to selection on plant and floral characters via female plant‐reproductive success in Castilleja linariaefolia (Scrophulariaceae). C. linariaefolia is pollinated by hummingbirds and experiences high levels of pre‐dispersal seed predation by plume moth and fly larvae in the Rocky Mountains of Colorado, USA, where this work was conducted. We first examined whether female reproduction in C. linariaefolia was limited by pollination. Supplemental pollination only marginally increased components of female reproduction, likely because seed predation masked, in part, the beneficial effects of pollen addition. In unmanipulated populations, we measured calyx length, flower production, and plant height and used path analysis combined with structural equation modeling to quantify their importance to relative seed set through pathways involving pollination vs seed predation. We found that the strength of selection on calyx length, flower production, and plant height was greater for seed predation pathways than for pollination pathways, and one character, calyx length, experienced opposing selection via pollination vs seed predation. These results suggest that the remarkable intraspecific variation in plant and floral characters exhibited by some flowering plants is likely the result of selection driven, at least in part, by pollinators in concert with antagonists, such as pre‐dispersal seed predators. This work highlights the subtle but complex interactions that shape floral and vegetative design in natural ecosystems. DA - 2004/1// PY - 2004/1// DO - 10.1111/j.0030-1299.2004.12641.x VL - 104 IS - 1 SP - 15-26 J2 - Oikos LA - en OP - SN - 0030-1299 1600-0706 UR - http://dx.doi.org/10.1111/j.0030-1299.2004.12641.x DB - Crossref ER - TY - JOUR TI - THE DUAL ROLE OF FLORAL TRAITS: POLLINATOR ATTRACTION AND PLANT DEFENSE AU - Irwin, Rebecca E. AU - Adler, Lynn S. AU - Brody, Alison K. T2 - Ecology AB - Plants are under siege from a diversity of enemies that consume both leaf and floral parts. Plants resist damage to leaves in a variety of ways, and we now have a rich literature documenting how plants defend themselves against herbivore attack. In contrast, the mechanisms by which plants resist enemies that consume floral parts or resources are much less known, even though damage to floral tissue usually has tighter links to plant fitness than damage to leaf tissue. Many plants experience nectar robbing, whereby floral visitors remove nectar from flowers, often without pollinating. Nectar robbers can reduce plant fitness to degrees comparable to, or even surpassing, reduction by herbivores. However, because nectar attracts both pollinators and nectar robbers, plants face a dilemma in defending against nectar robbers without also deterring pollinators. Here, we extend the conceptual framework of resistance to herbivores to include resistance to nectar robbers, focusing on nectar traits. We review published data and find that an array of nectar traits may deter robbers without deterring pollinators. Although resistance traits against robbers have been broadly identified, the costs and benefits of these traits in terms of plant fitness remain poorly understood. We present data showing that a nectar trait (dilute nectar) might directly, as well as indirectly, benefit plant fitness by deterring nectar-robbing bumble bees of Ipomopsis aggregata without deterring hummingbird pollinators. However, the magnitude of any plant fitness benefit will depend on the degree to which plants are pollen- vs. resource-limited in a given year. The results of our work offer both conceptual and empirical insight into how plants cope with attack by nonpollinating floral visitors through a relatively unexplored trait, nectar. DA - 2004/6// PY - 2004/6// DO - 10.1890/03-0390 VL - 85 IS - 6 SP - 1503-1511 J2 - Ecology LA - en OP - SN - 0012-9658 UR - http://dx.doi.org/10.1890/03-0390 DB - Crossref ER - TY - JOUR TI - Ecological and Evolutionary Consequences of Multispecies Plant-Animal Interactions AU - Strauss, Sharon Y. AU - Irwin, Rebecca E. T2 - Annual Review of Ecology, Evolution, and Systematics AB - ▪ Abstract Ecologists and evolutionary biologists are broadly interested in how the interactions among organisms influence their abundance, distribution, phenotypes, and genotypic composition. Recently, we have seen a growing appreciation of how multispecies interactions can act synergistically or antagonistically to alter the ecological and evolutionary outcomes of interactions in ways that differ fundamentally from outcomes predicted by pairwise interactions. Here, we review the evidence for criteria identified to detect community-based, diffuse coevolution. These criteria include (a) the presence of genetic correlations between traits involved in multiple interactions, (b) interactions with one species that alter the likelihood or intensity of interactions with other species, and (c) nonadditive combined effects of multiple interactors. In addition, we review the evidence that multispecies interactions have demographic consequences for populations, as well as evolutionary consequences. Finally, we explore the experimental and analytical techniques, and their limitations, used in the study of multispecies interactions. Throughout, we discuss areas in particular need of future research. DA - 2004/12/15/ PY - 2004/12/15/ DO - 10.1146/annurev.ecolsys.35.112202.130215 VL - 35 IS - 1 SP - 435-466 J2 - Annu. Rev. Ecol. Evol. Syst. LA - en OP - SN - 1543-592X 1545-2069 UR - http://dx.doi.org/10.1146/annurev.ecolsys.35.112202.130215 DB - Crossref ER - TY - JOUR TI - Linking economic activities to the distribution of exotic plants AU - Taylor, Brad W. AU - Irwin, Rebecca E. T2 - Proceedings of the National Academy of Sciences AB - The human enterprise is flooding Earth's ecosystems with exotic species. Human population size is often correlated with species introductions, whereas more proximate mechanisms, such as economic activities, are frequently overlooked. Here we present a hypothesis that links ecology and economics to provide a causal framework for the distribution of exotic plants in the United States. We test two competing hypotheses (the population-only and population-economic models) using a national data set of exotic plants, employing a statistical framework to simultaneously model direct and indirect effects of human population and ecological and economic variables. The population-only model included direct effects of human population and ecological factors as predictors of exotics. In contrast, the population-economic model included the direct effects of economic and ecological factors and the indirect effects of human population as predictors of exotics. The explicit addition of economic activity in the population-economic model provided a better explanation for the distribution of exotics than did the population-only model. The population-economic model explained 75% of the variation in the number of exotic plants in the 50 states and provided a good description of the observed number of exotic plants in the Canadian provinces and in other nations in 85% of the cases. A specific economic activity, real estate gross state product, had the strongest positive effect on the number of exotics. The strong influence of economics on exotics demonstrates that economics matter for resolving the exotic-species problem because the underlying causes, and some of the solutions, may lie in human-economic behaviors. DA - 2004/12/9/ PY - 2004/12/9/ DO - 10.1073/pnas.0405176101 VL - 101 IS - 51 SP - 17725-17730 J2 - Proc. Natl. Acad. Sci. U.S.A. LA - en OP - SN - 0027-8424 1091-6490 UR - http://dx.doi.org/10.1073/pnas.0405176101 DB - Crossref ER - TY - JOUR TI - Predation by the black-clawed mud crab,Panopeus herbstii, in Mid-Atlantic salt marshes: Further evidence for top-down control of marsh grass production AU - Silliman, Brian Reed AU - Layman, Craig A. AU - Geyer, Kane AU - Zieman, J. C. T2 - Estuaries DA - 2004/4// PY - 2004/4// DO - 10.1007/bf02803375 VL - 27 IS - 2 SP - 188-196 J2 - Estuaries LA - en OP - SN - 0160-8347 UR - http://dx.doi.org/10.1007/bf02803375 DB - Crossref ER - TY - CHAP TI - Snowshoe hares in a dynamic managed landscape AU - Griffin, P. C. AU - Mills, L. S. T2 - Species conservation and management : case studies A2 - Editors H. R. Akcakaya, M. A. Burgman A2 - O. Kindvall, C. Wood A2 - P. Sjogren-Gulve, J. Hatfield A2 - McCarthy, M. A. PY - 2004/// PB - New York : Oxford University Press SN - 9780195166460 ER - TY - JOUR TI - Recent record of a cougar (Puma concolor) in Louisiana, with notes on diet, based on analysis of fecal materials AU - Leberg, PL AU - Carloss, MR AU - Dugas, LJ AU - Pilgrim, KL AU - Mills, LS AU - Green, MC AU - Scognamillo, D T2 - SOUTHEASTERN NATURALIST AB - We report a sighting, supported by DNA evidence from a scat, of a cougar (Puma concolor) in southeastern Louisiana. The 16S-rRNA genotype obtained from mtDNA is one that is common throughout North America, making it difficult to determine the origin of the individual. Based on DNA and hair scale analysis, the scat contained the partially digested remains of a dog (Canis familiaris) and an eastern cottontail (Sylvilagus floridanus), indicating that the individual was successfully foraging on locally occurring prey. DA - 2004/// PY - 2004/// DO - 10.1656/1528-7092(2004)003[0653:rroacp]2.0.co;2 VL - 3 IS - 4 SP - 653-658 SN - 1938-5412 ER - TY - JOUR TI - Edge effects and isolation: Red-backed voles revisited AU - Tallmon, DA AU - Mills, LS T2 - CONSERVATION BIOLOGY AB - Abstract: We examined demographic responses of California red‐backed voles ( Clethrionomys californicus ) to forest fragmentation in southwestern Oregon at sites where this species has previously shown negative responses to fragmentation. Voles were captured in live traps and released. Voles were rarely caught in clearcuts surrounding 11 forest fragments, but relative vole density did not decrease from the forest‐fragment interiors to edges. The first result agrees with previous findings at these sites 6 years earlier, but the latter result does not. There was no evidence that vole response to edge changes with fragment age. Two years of intensive mark‐recapture efforts at two forest‐fragment sites and two unfragmented (control) sites did not show negative effects of fragmentation on vole survival, an important demographic rate. Vole capture probabilities varied greatly across space and time on these four sites, which may explain the differences in vole responses to edge seen between this and the previous study. These results suggest that reliable appraisal of edge effects may be difficult for many species on small fragments because the data necessary to apply population estimators require great efforts to obtain and the use of indices leads to a confounding of detection probabilities with demographic change. DA - 2004/12// PY - 2004/12// DO - 10.1111/j.1523-1739.2004.00439.x VL - 18 IS - 6 SP - 1658-1664 SN - 1523-1739 KW - abundance KW - density KW - edge effects KW - habitat fragmentation KW - metareplication KW - relative density KW - survival ER -