Meeting Abstract

44.7  Saturday, Jan. 5  Is thermal biology the missing factor in predator-induced life history plasticity? ARENDT, J. D.**; STORZ, B; Univ. of California, Riverside; Florida State University, Tallahassee jarendt@ucr.edu

Predation pressure induces plastic shifts in age and size at maturation in many species. Theory generally predicts early maturation at a small size in response to increased predation pressure. However, predators may have indirect effects on prey; if predators decrease competition (increasing per capita resource levels) they may induce earlier maturation at a larger size, if prey reduce activity or use shelter thus decreasing feeding rates then maturation may occur later and at a smaller size. Empirical examples also exist of predation pressure resulting in later maturation at a larger size although we know of no theoretical models that predict such a result. One way to get this pattern is if predators cause prey to use cooler habitats because delayed maturation at a larger size is a common response in ectotherms to cool temperatures. We discuss examples where predators likely alter thermal regime experienced by prey and provide evidence for such effects in one system, namely age and size at metamorphosis in larvae of Mexican spadefoot toads, and discuss potential long term population effects of this response.