The Layman Lab    aquatic ecology • food webs • restoration ecology • predator-prey interactions

Predator-driven Phenotypic Variation in Mosquitofish

The rapid and dramatic changes in biotic and abiotic characteristics following tidal creek fragmentation is predicted to generate substantially different selection pressures for organisms inhabiting the system than were naturally present before anthropogenic impacts. In this NSF funded project (with Brian Langerhans, North Carolina State University) we are testing a priori predictions of phenotypic differentiation based on explicit hypotheses of divergent natural selection between fragmentation regimes. Our model organism is a small endemic, livebearing fish species, Bahamas mosquitofish (Gambusia hubbsi). The work will determine the relative influence of natural selection in driving predictable phenotypic outcomes, the role of history (genetic drift and unpredictable events) in yielding stochastic phenotypic variation, and the importance of gene flow in constraining phenotypic divergence (and the reverse causation of divergent selection constraining gene flow).

Because organisms might respond to divergent natural selection across heterogeneous environments through the evolution of either phenotypic plasticity (environmentally-contingent phenotype production) or fixed genetic differences (genetic divergence in environmentally-insensitive phenotypes), the relative contributions of these sources of phenotypic variation on observed differences between G. hubbsi populations also will be assessed using laboratory-rearing experiments. Results of the proposed work will provide a better understanding of the breadth of consequences that human activities might induce, including both ecological and evolutionary implications.