The Peninsula Effect: Habitat-Correlated Species Decline in Florida's Herpetofauna

We examine the peninsula effect for Florida's amphibians and reptiles. Of 108 species that inhabit the peninsula, forty-eight fail to reach the peninsular tip. These form an unusually large concentration of tipward boundaries in a few counties along the mid-peninsula axis. A Monte Carlo simulation suggests that this concentration would not likely have arisen if the species boundaries were randomly and independently arranged. Nor is it likely that this peninsula effect is a historical legacy or a result of immigration-extinction dynamics. All but one of the forty-eight species sort into four natural groups by habitat preferences. Each of the four habitat categories either disappears or declines in per cent occurrence and/or quality tipward along the peninsula. By contrast, only one of the sixty-one species that inhabit the tip of the peninsula fails to reach the peninsular base. We believe the habitat reduction alone explains the peninsula effect in the Florida herpetofauna.