Behavioral changes in tadpoles after multigenerational exposure to an invasive intraguild predator

Prey subject to intraguild predation may face conflicting selective pressure on behavior, with competition favoring increased activity and predation favoring activity reduction. To discover how this evolutionary conflict might be resolved, we compared the behavior of tadpoles from four families drawn from different populations that had potentially co-evolved with an introduced intraguild predator for up to 90 years with the behavior of tadpoles from four families from unexposed populations. Intraguild prey were tadpoles of the declining California Red-legged Frog (Rana draytonii) and the intraguild predator was the invasive American Bullfrog (Lithobates catesbeianus), a voracious predator and strong competitor of other anurans. Limited evidence suggests that some native amphibians that have co-occurred with invasive predators for generations show adaptive behavioral responses to predator chemical cues. We tested whether R. draytonii larvae from families either allotopic or syntopic with...