Dispersal and Mating System in Populations of the Argentine Boa constrictor (Boidae)

CHIARAVIGLIO MARGARITA; BERTONA MIGUEL; RIVERA PAULA C.; GARDENAL CRISTINA N.

Florianópolis Brasil

Congreso; XXVIII International Ethological Conference.; 2003

Knowledge of dispersal is essential to understand the ecology of any species because population dynamics, spatial distribution and genetic structure are closely tied to patterns of movements. Dispersal remains one of the most enigmatic parameters in population biology. Reproductive enhancement through increased access to mates or resources and the avoidance of imbreeding are important in promoting sex differences in dispersal. Two different approachs were used to estimates dispersal in nature populations of Argentine boa constrictor at a local scale. We used telemetry, a direct method that shows actual observations of individuals movements, and an indirect method to infer movement using the distribution of alleles frequencies to estimates levels of gene flow. The former approach suggested that, in general, reproductive females moved shorter distances than non reproductive females and males. The latter showed a greater number of effective migrant per generation among male than among females, suggesting a male-biased dispersal strategy. These phenomena suggest a Prolonged Mate Searching Polygyny in this species. This mating system, in which males search for receptive females, occurs in several species differing in some aspect of their life history but sharing the similarity of receptive females being scarce and scattered in the environment. Hence, sexual selection should act on mate searching ability rather than male-male combat activity.