Data from: Intraspecific variation in mating behavior modulates the effects of mosquitofish introduction on prey communities

Intraspecific variation is recognized as a driver of ecological processes,
yet prior studies have overwhelmingly focused on the ecological effects of
intraspecific trait variation driven by natural selection. Far less is
known about how variation in sexually selected traits influences
ecological outcomes. In this study, we tested whether intraspecific
differences in reproductive behaviors affect the ecosystem- and
community-level impact of western mosquitofish (Gambusia affinis)
introductions. Male mosquitofish frequently harass females through
persistent mating attempts. We manipulated the intensity of male
harassment, then used a mesocosm experiment to measure the ecological
consequences of these differences in harassment. Although this behavior
manipulation was short-lived, our results suggest that differences in
harassment intensity affected zooplankton communities. Compared to
fish-absent controls, mesocosms with high-harassment males had smaller
zooplankton body size and reduced abundance in several dominant taxa.
These effects were not observed in low-harassment treatments, suggesting a
threshold response in which only high-harassment males elicited community
changes. The presence of mosquitofish also caused a trophic cascade to
impact phytoplankton biomass; however, the strength of this cascade was
not altered by harassment intensity. Our findings demonstrate that sexual
selection can shape community composition and shows that reproductive
behavior can modulate the impact of species introduction.