Ecological and morphological variation of darters among assemblages in Oklahoma streams

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Show simple item record Hopper, Garrett W. 2015-07-29T19:04:22Z 2015-07-29T19:04:22Z 2015-08-01 en_US
dc.description.abstract Environmental variation can shape phenotypic variation in organisms. Most evidence for trait differentiation along environmental gradients comes from analyses of dichotomous habitat types that differ in only one or few environmental factors. In reality, however, environmental variation is often more subtle, gradual, and multifarious. I investigated geographic variation in body shape, trophic resource use, and individual diet specialization in two species of darters (Etheostoma spectabile and E. flabellare; Percidae) that occur along river gradients. I explicitly tested how abiotic and biotic environmental factors shape trait variation within and between species. Results indicated significant among population variation in the body shape of both species. Population differences in body shape were correlated with variation in substrate composition. Although body shape analyses revealed a small but significant signal of convergent evolution of body shape when both species occur in sympatry, E. spectabile and E. flabellare mostly exhibited unique responses to shared sources of selection. The analyses of darter trophic resource use uncovered significant resource partitioning between the two species and geographic variation in diets that is likely driven by differences in resource availability. Furthermore, the majority of populations exhibited significant individual specialization. Variation in individual specialization in populations of E. flabellare was related to invertebrate density and competitor richness, and in E. spectabile to the combined effects of invertebrate density and invertebrate diversity. My results indicate substantial variation in trophic resource use among individuals, populations, and species of small-bodied fishes that are typically assumed to be generalist insectivores. Variation in diet specialization may be more widespread than previously considered, and ecological opportunity is an important factor in shaping trophic resource use of individuals and populations. Overall, the results indicate that even subtle and gradual environmental variation can induce substantial variation in phenotypes on a relatively small spatial scale. en_US
dc.description.sponsorship Oklahoma Department of Wildlife Conservation National Science Foundation en_US
dc.language.iso en_US en_US
dc.publisher Kansas State University en
dc.subject Ecological gradients en_US
dc.subject Darters en_US
dc.subject Local adaptation en_US
dc.subject Geometric morphometrics en_US
dc.subject Diet variation en_US
dc.subject Individual specialization en_US
dc.title Ecological and morphological variation of darters among assemblages in Oklahoma streams en_US
dc.type Thesis en_US Master of Science en_US
dc.description.level Masters en_US
dc.description.department Biology en_US
dc.description.advisor Michael Tobler en_US
dc.subject.umi Biology (0306) en_US
dc.subject.umi Ecology (0329) en_US 2015 en_US August en_US

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