@article{poteat_jacobus_buchwalter_2015, title={The importance of retaining a phylogenetic perspective in traits-based community analyses}, volume={60}, ISSN={["1365-2427"]}, DOI={10.1111/fwb.12571}, abstractNote={1) Many environmental stressors manifest their effects via physiological processes (traits) that can differ significantly among species and species groups. We compiled available data for three traits related to the bioconcentration of the toxic metal cadmium (Cd) from 42 aquatic insect species representing orders Ephemeroptera (mayfly), Plecoptera (stonefly), and Trichoptera (caddisfly). These traits included the propensity to take up Cd from water (uptake rate constant, ku), the ability to excrete Cd (efflux rate constant, ke), and the net result of these two processes (bioconcentration factor, BCF). 2) Ranges in these Cd bioaccumulation traits varied in magnitude across lineages (some lineages had a greater tendency to bioaccumulate Cd than others). Overlap in the ranges of trait values among different lineages was common and highlights situations where species from different lineages can share a similar trait state, but represent the high end of possible physiological values for one lineage and the low end for another. 3) Variance around the mean trait state differed widely across clades, suggesting that some groups (e.g., Ephemerellidae) are inherently more variable than others (e.g., Perlidae). Thus, trait variability/lability is at least partially a function of lineage. 4) Akaike information criterion (AIC) comparisons of statistical models were moremore » often driven by clade than by other potential biological or ecological explanation tested. Clade-driven models generally improved with increasing taxonomic resolution. 5) Altogether, these findings suggest that lineage provides context for the analysis of species traits, and that failure to consider lineage in community-based analysis of traits may obscure important patterns of species responses to environmental change.« less}, number={7}, journal={FRESHWATER BIOLOGY}, author={Poteat, Monica D. and Jacobus, Luke M. and Buchwalter, David B.}, year={2015}, month={Jul}, pages={1330–1339} }
 @article{poteat_buchwalter_2014, title={Calcium uptake in aquatic insects: influences of phylogeny and metals (Cd and Zn)}, volume={217}, ISSN={["1477-9145"]}, DOI={10.1242/jeb.097261}, abstractNote={Calcium sequestration in the hypo-osmotic freshwater environment is imperative in maintaining calcium homeostasis in freshwater aquatic organisms. This uptake process is reported to have the unintended consequence of potentially toxic heavy metal (Cd, Zn) uptake in a variety of aquatic species. However, calcium uptake remains poorly understood in aquatic insects, the dominant invertebrate faunal group in most freshwater ecosystems. Here, we examined Ca uptake and interactions with heavy metals (Cd, Zn) at low ambient Ca levels (12.5 μmol l−1) in 12 aquatic insect species within Ephemerellidae (mayfly) and Hydropsychidae (caddisfly), two families differentially responsive to trace metal pollution. We found Ca uptake varied 70-fold across the 12 species studied. Body mass and clade (family) were found to significantly influence both Ca uptake and adsorption (P≤0.05). Zn and Cd uptake rate constants (ku) exhibited a strong correlation (r=0.96, P<0.0001), suggesting a shared transport system. Ca uptake failed to significantly correlate with either Zn or Cd ku values. Further, neither Zn nor Cd exhibited inhibitory effects toward Ca uptake. In fact, we saw evidence of modest stimulation of Ca uptake rates in some metal treatments. This work suggests that insects generally differ from other freshwater taxa in that aqueous Ca uptake does not appear to be compromised by Cd or Zn exposure. It is important to understand the trace metal and major ion physiology of aquatic insects because of their ecological importance and widespread use as ecological indicators.}, number={7}, journal={JOURNAL OF EXPERIMENTAL BIOLOGY}, author={Poteat, Monica D. and Buchwalter, David B.}, year={2014}, month={Apr}, pages={1180–1186} }
 @article{poteat_buchwalter_2014, title={Four Reasons Why Traditional Metal Toxicity Testing with Aquatic Insects Is Irrelevant}, volume={48}, ISSN={["1520-5851"]}, DOI={10.1021/es405529n}, abstractNote={T metal contamination of freshwater ecosystems is a problem worldwide, and insects are typically the predominant invertebrate faunal group in these systems. Metals can shape community structure, as evidenced by reduced biodiversity in affected areas. Aquatic insects are often some of the first species to disappear from metal-contaminated sites, despite the fact that laboratory toxicity tests would suggest that aquatic insects are generally insensitive to metals. In fact, typical laboratory results would indicate that insects only respond to dissolved metals at concentrations orders of magnitude larger than those found in the most insect-depleted contaminated sites. Even with mounting evidence highlighting the obvious disconnect between laboratory toxicity tests and field observations regarding metal toxicity to aquatic insects, water quality criteria for metals continues to rely primarily on toxicity values derived from short term dissolved-only exposures. Below we discuss four key reasons as to why such tests don’t provide relevant data for this important faunal group, focusing upon recent advances in our understanding of bioaccumulation and mechanisms of toxicity.}, number={2}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Poteat, Monica D. and Buchwalter, David B.}, year={2014}, month={Jan}, pages={887–888} }
 @article{poteat_buchwalter_2014, title={Phylogeny and Size Differentially Influence Dissolved Cd and Zn Bioaccumulation Parameters among Closely Related Aquatic Insects}, volume={48}, ISSN={["1520-5851"]}, DOI={10.1021/es501096a}, abstractNote={Evolutionarily distinct lineages can vary markedly in their accumulation of, and sensitivity to, contaminants. However, less is known about variability among closely related species. Here, we compared dissolved Cd and Zn bioaccumulation in 19 species spanning two species-rich aquatic insect families: Ephemerellidae (order Ephemeroptera (mayflies)), generalized to be metal sensitive, and Hydropsychidae (order Trichoptera (caddisflies)), generalized to be metal tolerant. Across all species, Zn and Cd uptake rate constants (k(u)s), efflux rate constants (k(e)s) and bioconcentration factors (BCFs) strongly covaried, suggesting that these metals share transport pathways in these distinct lineages. K(u)s and BCFs were substantially larger in Ephemerellidae than in Hydropsychidae, whereas k(e)s did not dramatically differ between the two families. Body size played an important role in driving ku differences among species, but had no influence on k(e)s. While familial differences in metal bioconcentration were striking, each family exhibited tremendous variability in all bioaccumulation parameters. At finer levels of taxonomic resolution (within families), phylogeny did not account for differences in metal bioaccumulation. These findings suggest that intrafamily variability can be profound and have important practical implications in that we need to better understand how well "surrogate species" represent their fellow congeners and family members.}, number={9}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Poteat, Monica D. and Buchwalter, David B.}, year={2014}, month={May}, pages={5274–5281} }
 @article{poteat_garland_fisher_wang_buchwalter_2013, title={Evolutionary Patterns in Trace Metal (Cd and Zn) Efflux Capacity in Aquatic Organisms}, volume={47}, ISSN={["1520-5851"]}, DOI={10.1021/es401368u}, abstractNote={The ability to eliminate (efflux) metals is a physiological trait that acts as a major driver of bioaccumulation differences among species. This species-specific trait plays a large role in determining the metal loads that species will need to detoxify to persist in chronically contaminated environments and, therefore, contributes significantly to differences in environmental sensitivity among species. To develop a better understanding of how efflux varies within and among taxonomic groupings, we compared Cd and Zn efflux rate constants (ke values) among members of two species-rich aquatic insect families, Ephemerellidae and Hydropsychidae, and discovered that ke values strongly covaried across species. This relationship allowed us to successfully predict Zn efflux from Cd data gathered from aquatic species belonging to other insect orders and families. We then performed a broader, comparative analysis of Cd and Zn ke values from existing data for arthropods, mollusks, annelids, and chordates (77 species total) and found significant phylogenetic patterns. Taxonomic groups exhibited marked variability in ke magnitudes and ranges, suggesting that some groups are more constrained than others in their abilities to eliminate metals. Understanding broader patterns of variability can lead to more rational extrapolations across species and improved protectiveness in water-quality criteria and ecological assessment.}, number={14}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Poteat, Monica D. and Garland, Theodore, Jr. and Fisher, Nicholas S. and Wang, Wen-Xiong and Buchwalter, David B.}, year={2013}, month={Jul}, pages={7989–7995} }
 @article{poteat_diaz-jaramillo_buchwalter_2012, title={Divalent metal (Ca, Cd, Mn, Zn) uptake and interactions in the aquatic insect Hydropsyche sparna}, volume={215}, ISSN={["1477-9145"]}, DOI={10.1242/jeb.063412}, abstractNote={SUMMARY Despite their ecological importance and prevalent use as ecological indicators, the trace element physiology of aquatic insects remains poorly studied. Understanding divalent metal transport processes at the water–insect interface is important because these metals may be essential (e.g. Ca), essential and potentially toxic (e.g. Zn) or non-essential and toxic (e.g. Cd). We measured accumulation kinetics of Zn and Cd across dissolved concentrations ranging 4 orders of magnitude and examined interactions with Ca and Mn in the caddisfly Hydropsyche sparna. Here, we provide evidence for at least two transport systems for both Zn and Cd, the first of which operates at concentrations below 0.8 μmol l–1 (and is fully saturable for Zn). We observed no signs of saturation of a second lower affinity transport system at concentrations up to 8.9 μmol l–1 Cd and 15.3 μmol l–1 Zn. In competition studies at 0.6 μmol l–1 Zn and Cd, the presence of Cd slowed Zn accumulation by 35% while Cd was unaffected by Zn. At extreme concentrations (listed above), Cd accumulation was unaffected by the presence of Zn whereas Zn accumulation rates were reduced by 58%. Increasing Ca from 31.1 μmol l–1 to 1.35 mmol l–1 resulted in only modest decreases in Cd and Zn uptake. Mn decreased adsorption of Cd and Zn to the integument but not internalization. The L-type Ca2+ channel blockers verapamil and nifedipine and the plasma membrane Ca2+-ATPase inhibitor carboxyeosin had no influence on Ca, Cd or Zn accumulation rates, while Ruthenium Red, a Ca2+-ATPase inhibitor, significantly decreased the accumulation of all three in a concentration-dependent manner.}, number={9}, journal={JOURNAL OF EXPERIMENTAL BIOLOGY}, author={Poteat, Monica D. and Diaz-Jaramillo, Mauricio and Buchwalter, David B.}, year={2012}, month={May}, pages={1575–1583} }