Biogeography of scavenging scarab beetles in the Florida Keys: post-Pleistocene land-bridge islands

Abstract

Fieldwork on 15 islands of the Florida Keys produced 13 species of scavenging scarab beetles (Laparosticti and Trox). Six of these species represent new records for the Keys. Twenty-three additional species (many of which are synanthropic or tramps), previously recorded from the Keys, were not found. Species–area relationships for the islands form a significant regression line as predicted by equilibrium island biogeography theory. It is concluded that many of the islands have low species numbers either because (i) human habitat disturbance has caused many local species extinctions or (ii) species turnover rates (extinction over immigration) are high because of scarcity of suitable hosts or adverse soil conditions. Data from highly disturbed Key West and Stock Island suggest that as species turnover continues, higher species saturation levels may be regained through the immigration of synanthropic and tramp species. This work generally points to the lack of much basic information on scarab beetle bionomics.