Causes, Consequences, and Breadth of Body Shape/Habitat Associations

Texas A&M Research Foundation, College Station TX

Investigators

Abstract

What are the nature and consequences of genetic and body-shape differentiation in natural populations of fishes? This empirical system involves body shape in small fishes exposed to varied predation risk from larger fishes. Preliminary results indicate that at least four species of livebearing fishes from disparate regions diversify in a similar manner across predatory environments. This shared axis of differentiation explains 37% of shape variation among all fish, regardless of species. Preliminary performance data suggest that the strong axis of shape change between predator-prone and predator-free habitats is positively correlated with explosive swimming speed, but negatively related to endurance swimming. This tradeoff (divergent natural selection) is a likely cause of diversification. The goals of this project are to develop a general method for partitioning genetic and phenotypic differentiation into shared (general) and unique (species- or population-specific) responses. This theoretical framework stem from an important group of fishes that face many conservation challenges involving at least three extinctions and seven endangered or threatened species in the United States. The research is the core of a larger project that establishes an international collaboration with a molecular geneticist and a community ecologist. Mexican scientists and their students will work collaterally and be trained in morphometrics by the PI. Synergistic efforts will also involve an environmental physiologist and graduate student in the mechanisms of the tradeoff in performance. A graduate student, technician, and undergraduate students will be trained during this project.