Drivers and cascading ecological consequences of Gambusia affinis trait variation

Phenotypic trait differences among populations can shape ecological outcomes for communities and ecosystems. However, few studies have mechanistically linked heritable and plastic components of trait variation to generalizable processes of ecology, such as trophic cascades. Here we assess morphological and behavioral trait variation in nine populations of common-garden reared western mosquitofish (Gambusia affinis) from three distinct ancestral predator environments (three populations per environment), each reared in the presence and absence of predator cues. We then use a pond mesocosm experiment to examine the ecological consequences of trait variation and density variation. Our results show significant among-population trait variation, but this variation was generally unrelated to ancestral predator environment. When traits did vary congruently with respect to ancestral predator environment, this trait variation was driven by gene-by-environment interactions. Variation in several mos...