Meeting Abstract
Polyphenic populations are a valuable resource for understanding the relationship between form and function. Morphological variation within a population can have dramatic impacts on performance and subsequently fitness. In Lake Waban (Wellesley, MA), bluegill Lepomis macrochirus have diverged into two ecomorphs, which occupy pelagic and littoral habitats. Based on morphological variation of the oral jaws and diet studies, we hypothesized that littoral individuals would use more suction during feeding than pelagic fish. To address this hypothesis, we measured pressure and kinematics during prey capture on earthworms, mealworms and brine shrimp. We found that littoral fish used more suction when feeding on all prey types and varied their feeding behaviors depending on prey type. Similarly, the littoral ecomorph traveled a greater distance during feeding, suggesting that they use more ram than the pelagic fish. Pelagic bluegills exhibited a stereotyped feeding behavior for all prey types, which suggests that they have reduced modularity during feeding. These results give further credence to the divergence in behavior and morphology that is seen when comparing two phenotypes of bluegill. The stereotyped behavior reflects previous work on cichlids which are pelagic prey specialists. The results from our study suggest that pelagic bluegills undergo a behavioral shift that allows them to specialize on pelagic prey. Conversely, littoral fish maintain a varied diet which allows them to feed on a variety of prey items.
