Meeting Abstract

S7-1.5  Saturday, Jan. 5  Predictability of morphological differentiation across flow regimes in fishes LANGERHANS, Brian; Harvard University langerhans@oeb.harvard.edu

Fish inhabit environments greatly varying in the intensities of water velocities experienced, and flow regime is generally believed to be of major evolutionary significance. While a sizeable volume of research has examined morphological variation across flow gradients in fishes, no clear consensus regarding the general magnitude or nature of water velocity�s effects on fish morphology has yet emerged. Here I illustrate a generalized model (owing homage to Arnold’s morphology -> performance -> fitness model) that can be used to produce testable hypotheses for the effects of water flow on fish morphology. The model applies to most fish and combines biomechanical information (describing how fish morphology determines swimming performance) with ecological information (describing how swimming performance influences fitness) to yield predictions of divergent evolutionary trajectories in low- versus high-flow environments. Based on theory and empirical work, the model assumes we understand how fish swim and how selection favors either steady or unsteady swimming abilities under varying flow regimes. I test the model�s predictions using meta-analysis and point to avenues of future research that appear particularly promising. Results suggest that this relatively simple, generalized model should provide a nice framework for future investigations of ecomorphological variation across aquatic flow regimes.