Sean Keogh

PhD Student, Ecology, Evolution, and Behavior

Identifying the forces responsible for the convergent evolution of similar morphologies in distantly related taxa is fundamental to understanding patterns of phenotypic diversity within biotic communities and moreover is a key objective of evolutionary biology. Many studies have found instances of convergent morphology that correlate with ecology, suggesting the convergent evolution of similar ecological niches can drive the evolution of similar morphologies.

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Freshwater bivalves (Order Unionida), a monophyletic radiation, exhibit a striking diversity of shell morphologies, some of which are not shared by their marine relatives. Distinct morphology themes can be qualitatively categorized across the diversity of freshwater bivalves, suggesting multiple independent origins of morphology themes.

My research uses unionid mussels as a model to study convergent morphological evolution. First, I am testing for the frequency of morphological convergences by constructing a phylogeny and measuring shape using CT-scanning and 3D geometric morphometrics. Second, I am testing how shell shape convergences correlate to ecological variables (i.e. substrate, flow) by testing the performance of shell convergences under different environmental conditions.