Sex biased dispersal and high levels of gene flow among local populations in the argentine boa constrictor, Boa constrictor occidentali

RIVERA, P.C., GARDENAL, C.N. Y CHIARAVIGLIO, M.

AUSTRAL ECOLOGY

Año: 2006 vol. 31 p. 948 - 955

1442-9985

ABSTRACT The knowledge of dispersal is essential to understand the ecology of any species, since population dynamics, spatial distribution and genetic structure are closely tied to patterns of movement. In order to contribute to the understanding of the endangered snake Boa constrictor occidentalis (Serpentes, Boidae), we used allozymes as genetic markers to estimate dispersal patterns in natural populations. Blood samples were obtained from a total of 120 adult individuals of nine localities from two areas, Sobremonte and Pocho in Cordoba, Argentina. Only four out of a total of 24 loci were polymorphic: 6-Pgdh-1, Cat-1, Ldh and Hp. The values of P, A, Ho and He indicate low levels of genetic variability in this snake. FST mean value was 0.0089 and 0.0379 among populations of Sobremonte and Pocho respectively. A mean effective number of 46.1 and 7.46 migrants per generation was estimated in those areas, indicating important levels of gene flow. A comparison of Nem between genders in both areas suggests a greater dispersal success and/or longer distance dispersal of males than females, which could be explained by the characteristics of the mating system. KEY WORDS: Boa constrictor occidentalis, snake, gene flow, allozymes, sex biased dispersal