Influence Of Landscape Connectivity On Polimorphism And Genetic Structure In Populations Of Argentine Boa Constrictor (Boa constrictor occidentalis)

CARDOZO GABRIELA; RIVERA PAULA C.; LAMFRI MARIO; SCAVUZO MARCELO; GARDENAL CRISTINA N.; CHIARAVIGLIO MARGARITA

Córdoba Argentina

Congreso; XV Jornadas Científicas de la Sociedad de Biología de Córdoba; 2005

Sociedad de Biología de Córdoba

Many species´ ecological processes are sensitive to spatial heterogeneity. How a species responds to the heterogeneous distribution of habitat and resources may strongly influence its long-term persistence. The aim of this work was to evaluate variations in polymorphism and genetic structure of Argentine boa constrictor populations and landscape composition as a whole. Therefore, we analyzed the way in which heterogeneous spatial patterns would influence the genetic process. The less landscape connectivity and integrity there are, the lower levels of gene flow and genetic variability we may expect. The study population’ areas were located in the west regions of Districts of Pocho and Sobremonte in Córdoba Province. We estimated genetic variability and levels gene flow for each area using isozimes and ISSR as molecular markers. In order to characterize the landscape composition in terms of vegetation structures we analyzed satellital images Landsat 5 TM. Next, we carried out the supervised image classification and by applying majority analysis, we made the patches clumper. The forest fragmentation pattern was analyzed through connectivity and isolation metrics obtained by FragStats 3.3. The genetic variability was similar in both regions, however the level of gene flow was higher in Sobremonte than Pocho. The variation of genetic parameters may be caused by the distinct features in the landscape degradation stages. In Pocho, the study area is characterized by a high fragmentation level being composed by small forest units isolated by shrublands of jarilla (Larrea divaricata). In contrast, the forest in Sobremonte is more continue staying under a slighter degradation process called perforation. This process leads to habitat loss but it does not  reduce the landscape connectivity. This novel approach integrating and analyzing genetic and environmental data, using geographic information systems and molecular methods, will help us to understand the effects of land transformation on species’ ecology and will provide critical knowledge to develop conservation strategies.