REU: Intraspecific Variation and Evolutionary Innovation

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A two-year continuation of current research is proposed with projects designed to uncover how variability, inheritance, and differential fitness affect the evolution of morphological variation within species of animals. The polymorphic tiger salamander, Ambystoma tigrinum, will be a model to address three questions. 1). Have changes in timing of development over evolutionary time affected the origin of morphological variation within species? 2) Will simple extensions of genetic models describing continuous variation in species? 3) Is natural selection, especially through competition within species and predictability of the aquatic habitat, a force maintaining morphological variation within and between populations? These questions relate to the general issue of how continuous morphological variation within a species is maintained or converted into discontinuous morphological variation within or between populations. Questions will be studied using laboratory and field experiments and observations. These include morphometric analyses of changes in size and shape as animals grow, complemented by descriptions of geographic variation in morphology. Breeding experiments will quantify genetic and environmental contributions to morphological variation among populations. Finally, several experiments are designed to provide a means for relating variation in anatomy, diet, and fitness. Collectively, the research projects proposed contribute to our developing understanding of the ecological and evolutionary processes relating variation within species and the origin of novel evolutionary forms.