Amphibians exhibit high levels of phenotypic plasticity in time and size at metamorphosis in response to a variety of different environmental characteristics. Environmental characteristics can also induce changes in morphology. Previous work shows that intraspecific competition can alter the length of metamorph legs relative to their body size, though the differences among treatment often are small. Here, I show that relative leg length (leg length/body length) can be quite variable, as seen in four different species: Hyla versicolor, Lithobates sylvaticus, Lithobates sphenocephalus, and Anaxyrus americanus under experimental conditions. I measured relative leg length for metamorphs from aquatic mesocosm studies examining the effects of resource type and quality in the form of plant litter input.
Results/Conclusions
In most cases, treatments with lower resources (either no plant litter or plant litter with very low nutrient content, such as white pine) resulted in metamorphs with shorter legs relative to body length than treatments with higher resources. This effect of resource level on leg length suggests individual fitness consequences for metamorphs that spent their larval period in lower resource environments, such as closed canopy ponds with low quality leaf litter input. Shorter relative leg length was often highly correlated with body length and mass, but not time to metamorphosis. Metamorphs with shorter leg length often have reduced jumping performance. The correlation between relative leg length and body size may be one contributing mechanism to the general relationship between size at metamorphosis and fitness.