Effects of habitat loss on the Argentine Boa Constrictor (Boa constrictor occidentalis)

CARDOZO GABRIELA; RIVERA PAULA C.; GARDENAL CRISTINA N.; CHIARAVIGLIO MARGARITA

Tampa Florida EEUU

Congreso; Annual Joint Meetings of Society for the Study of Amphibians and Reptiles (SSAR); 2005

Identifying how habitat loss and fragmentation affect species ecology is a critical step in designing conservation strategies. Dispersal is one of the main processes influenced by the spatial and temporal distribution of critical resources in the landscape. In order to evaluate if habitat features could affect gene flow in populations of Boa constrictor occidentalis, which is a threatened species of South America herpetofauna included in the Apendix I of CITES, we characterized landscape physiognomical vegetation composition in two areas of Córdoba province, Pocho and Sobremonte, and related it with the population dispersal levels from each area. Using a geographic information system with Landsat 5 TM satellite images and performing field visits, we developed a supervised classification to identify and quantify the habitat composition of the study areas. Considering that our previous studies about habitat use indicate forest as the most suitable environment for the Argentine Boa Constrictor, we measured the fragmentation of this vegetation structure. We also calculated levels of dispersal using allozymes and ISSR-PCR as molecular markers to estimate gene flow in both areas. The supervised classification revealed that Sobremonte maintains greater forest coverage percentage than Pocho. Besides, the fragmentation analysis indicated that the forest patches are larger and nearer in Sobremonte. According to these results, gene flow was higher in Sobremonte than in Pocho suggesting that levels of dispersal in B. c. occidentalis decrease due to the fragmentation of suitable habitats. In consequence, the present tendency of changing in the Gran Chaco landscape, that is characterized by the intensification of farming and exploitation of natural woodland areas, could be a major reason for populations of Argentine Boa Constrictor become isolated.