Fortune may favor the flexible: environment-dependent behavioral shifts in invasive coquí frogs.

Biological invasions are a major driver of global biodiversity loss, impacting endemic species, ecosystems, and economies. Although the influence of life history traits on invasive success is well-established, the role of behavior in the invasive potential of animals is less studied. The common coquí frog, Eleutherodactylus coqui, is a highly successful invader in Hawai'i. We build on previous research characterizing changes in physiology and morphology to explore behavioral variation across the invasive range of coquí in Hawai'i. Coquí have expanded both outward and upward from their initial introduction site, and-by comparing frogs from different densities and elevations-we specifically asked how the physiological challenges of high-elevation living interact with the competitive challenge of high-densities at population centers. To investigate whether differences in the field represent local adaptation or behavioral plasticity, we additionally evaluated behavior following acclimation to a shared laboratory environment. Although we identified only subtle behavioral variation among populations in the field, we found that individuals from all populations became less bold, active, and exploratory in the laboratory, converging on a similar behavioral phenotype. Alongside previous work, our results suggest that coquí adjust their behavior to local environmental conditions across their invasive range and that behavioral flexibility may contribute to invasive success.