PARENT SESSION
Poster Session #52: Evolutionary Ecology.
Thursday, August 8. Presentation from 8:00 AM to 9:30 AM. Exhibit Hall B & C, TCC

Genetic variation in phenotypic plasticity in a freshwater snail.

Brunkow, Paul^*,1, Manuel, Amanda¹, ¹ Southern Illinois University Edwardsville, Edwardsville, IL

ABSTRACT- Changes in shell shape in response to predator cues are well documented in freshwater snails of the genus Physa. Individuals will develop relatively rotund shells in the presence of fish predator cues and will develop relatively slender shells in the presence of crayfish cues. Previous studies have demonstrated that these responses are adaptive as each shell shape lowers the risk of predation by fish or crayfish, respectively. In this study, we raised replicate groups of full siblings (families) in the presence of either no predator cues or crayfish cues. Shell shape was then compared between predator cue treatments among families as well as between each group of siblings within families. Shells were significantly more slender in crayfish treatments, in accord with prior studies. Mean difference in shell shape between no predator and predator treatments also differed significantly between families, suggesting a high degree of genetic variation for phenotypic plasticity in natural populations of this species. Importantly, plasticity of response varied depending upon which descriptor of shell shape was analyzed, and some families actually showed a response to the predator cue opposite to what was predicted.

KEY WORDS: snails, phenotypic plasticity, predator-prey interactions