Intraspecific variation in the population genetic structure of Ctenomys talarum.

CUTRERA, A.P. & E. A. LACEY.

Texas Tech University. Lubbock, Texas, USA

Congreso; 83rd Annual Meeting of the American Society of Mammalogists.; 2003

American Society of Mammalogists

Understanding the processes that shape genetic variation within and among populations is a fundamental goal in evolutionary research. Differences in mating system, dispersal patterns, and population density are expected to affect genetic structure and, hence, comparative studies of populations of conspecifics that differ with respect to these attributes provide a powerful tool for elucidating the effects of these variables on genetic structure. Ctenomys talarum (Ctenomyidae) is a subterranean rodent that occurs among coastal and sand dunes in Buenos Aires Province, Argentina. Previous studies of this species have revealed that populations at Mar de Cobo (MC) and Necochea (N), which are separated by ~ 150 km, differ significantly with respect to several fundamental population attributes. Specifically, adult density is higher, sex ratios are more female biased, dispersal is more male biased, and polygyny is more pronounced in the MC population than in the N population. Given the behavioral and demographic differences mentioned above, it is expected that Ne will be smaller in the MC population compared to that in the N population, leading to lower levels of genetic variability in MC population and greater genetic differentiation among its subpopulations due mainly to stochastic processes. To test these predictions, all individuals in two ~ 1ha areas at MC and in two ~ 1.5 ha areas at N were live-trapped during both the reproductive ® and non-reproductive (NR) portions of the year. All animals caught were individually marked using an ankle ring; a non-destructive skin sample was obtained from each individual captured. Levels of genetic variation within each population were assessed using microsatellite markers developed for ctenomyids. The results of these genetic analyses are discussed with regard to the demographic and behavioral differences evident among the study populations.