Allozymic polymorphism and genetic differentiation among populations of Calomys musculinus and Calomys laucha (Rodentia: Muridae) from eastern Argentina

Abstract

Summary The genetic variability and divergence among natural populations of Calomys musculinus and C. laucha from eastern Argentina were examined by protein electrophoresis of 24 loci. High levels of genetic variability were found in both species when compared to other rodents and mammals. Mean expected heterozygosity (He) ranged from 0.112 to 0.156, proportion of polymorphic loci (P 95% ) from 37.5% to 50% and mean number of alleles per locus (A) of 1.6-1.7 for C. musculinus . H e from 0.097 to 0.126, P 95% from 34.8 to 39.1 and A from 1.7 to 1.9 were the values for C. laucha . Populations of this last species revealed a higher degree of geographical differentiation (Θ = 0.017, P C. musculinus (Θ = 0.002, P > 0.05). These results are in agreement with the known social structure and habitat of both species. C. musculinus is an opportunistic species, with a loose social structure and a predominance of transient over resident animals, indicating a high ambulatory activity. C. laucha , on the contrary, inhabits almost exclusively cultivated fields, and evidence of social stratification has been reported for this species.