Phenotypic plasticity in complex environments: effects of structural complexity on predator- and competitor-induced phenotypes of tadpoles of the wood frog, Rana sylvatica

Abstract

Theoretical and empirical research has demonstrated that phenotypically plastic responses to one environment are dependent on other environmental attributes. Such research is critical considering the complexity of natural habitats, yet few studies have examined how multiple environments affect patterns of plasticity and the adaptiveness of the resulting phenotypes within complex habitats. The present study examines how wood frog (Rana sylvatica) tadpoles alter their behavioural and morphological phenotypes in response to predation risk from larval diving beetles (Dytiscus spp.), competition from conspecifics, and physical structural complexity. It also tests whether structure affects selection intensities by Dytiscus larvae on tadpole morphological traits. Predation risk and competition induced typical changes to tadpole behaviour and morphology. Structure did not induce changes to any phenotype, nor did it interact with predation risk or competition in affecting phenotypes. Furthermore, structure did not affect the predator selection intensities on any morphological trait. Dytiscus larvae selected for shallow, short tailfins, and large tail muscles, yet tadpoles only developed deep tail muscles when raised in the presence of predator cues. These apparently maladaptive responses may have been a result of correlations between phenotypes. The present study expands plasticity research by examining the adaptiveness of plastic responses in complex environments. Additionally, the present study demonstrates that not all environments induce plastic responses.