Meeting Abstract

P3.28  Wednesday, Jan. 6  Global patterns of body size in turtles COX, Christian L*; ANDERS, Michael B.; University of Texas, Arlington; University of Texas, Arlington clcox@uta.edu

The influence of body size on species assemblage has been demonstrated for cosmopolitan groups of organisms that are both species rich and ecologically diverse. However, global patterns of body size for species-poor groups of organisms that are morphologically and/or ecologically restricted have not previously been assessed. We analyzed global body size distributions for turtles, and examined the roles of continental origin, insularity, evolutionary lineage, habitat use, and species richness in the structuring of body size distributions. We compiled body size and ecological data from the literature using multiple sources. Body size distributions were analyzed using distributional statistics, nonparametric tests and resampling statistics. We found that while the global and all continental body size distributions are structured in a similar form, fixed lineage effects lead to considerable variation in body size distributions among families. For global, continental and family body size distributions there is evidence of a strong minimum limit on body size that suggests the external shell is a biomechanical constraint at small sizes. We found that body size distributions for both insular and terrestrial species are influenced by the evolution of large body size by many insular terrestrial turtle species, primarily those of the family Testudinidae. Additionally, the negative relationship between species richness and body size suggests either higher diversification rates of turtles with small body sizes or greater extinction probabilities of large bodied turtles.