Meeting Abstract

P2.96  Saturday, Jan. 5  Investigation of the Island Rule in Anurans: A Comparative Study of Hyla cinerea and Anaxyrus fowleri BOWER, C.D.**; BARRILE, G.M.; DOWNS, L.K.; KLINGER, J.M.; MOORE, J.T.; Bloomsburg University, Bloomsburg cdb84667@huskies.bloomu.edu

Studies of body size evolution disagree on evolutionary and ecological mechanisms of body size in island populations. The Island Rule hypothesis predicts that small insular vertebrate carnivores evolve to display gigantism. We studied a case of island dwarfism in anurans, small vertebrate carnivores, comparing Fowler’s toads and green tree frogs on barrier islands to nearby mainland populations on the eastern shore of Virginia. In contrast to the Island Rule, island toads (Anaxyrus fowleri) display a significant body reduction (about 20%) compared to their mainland counterparts. Is this due to evolution or environmental stresses on the island? Evidence from a common garden experiment investigating Fowler’s toads suggests similar larval growth rates, development, and size at metamorphosis of island and mainland tadpoles. We decided to conduct a comparative study to better understand if insular dwarfism in anurans is unique to Fowler’s toads, or if other anuran species inhabiting the islands show similar differences to mainland conspecifics. We collected mature male green tree frogs (Hyla cinerea) from four different habitats (two island, two mainland) and characterized the snout to vent lengths of each population. Results suggest that, similar to the Fowler’s toads, green tree frogs also display a reduction in body size (about 6%) from their mainland counterparts. These results suggest that barrier island environments strongly influence the growth and body size of anurans.