Meeting Abstract

36-6  Tuesday, Jan. 5 09:15  Relative contribution of genetic and ecological factors to morphological differentiation in island populations of Anolis sagrei WEGENER, JE*; MULDER, KP; PRINGLE, RM; KARTZIEL, TR; LOSOS, JB; KOLBE, JJ; University of Rhode Island, Kingston; University of Porto, Portugal ; Princeton University, NJ; Princeton University, NJ; Harvard University, Cambridge, MA; University of Rhode Island, Kingston johanna_wegener@my.uri.edu

Morphological differentiation among populations can be influenced by a number of evolutionary mechanisms, including gene flow, genetic drift and adaptation to local environmental conditions. Island systems are ideal to study underlying mechanisms of morphological differentiation, because gene flow is limited and populations may be largely independently evolving units. We sampled male and female brown anoles (Anolis sagrei) from 16 island populations near Staniel Cay in the Bahamas. To test what factors drive morphological differentiation among populations, we measured seven morphological variables of body size and shape, genotyped 10 microsatellite loci, collected structural microhabitat use data (i.e., perch height and diameter) and estimated population densities. We found significant morphological differentiation among island populations and between males and females. These differences could not be explained by variation in structural habitat use, geographic distance, or genetic distance (Fst). High genetic differentiation and signatures of genetic bottlenecks suggest that founder effects might be an important initial driver of morphological differentiation. We found that head length and injury rate in both males and females increase with population density, suggesting that competition might play a role in some aspects of morphological differentiation. Population densities can change rapidly over time and more work is needed to determine if morphological traits respond to these changes.