The Genetic Structure of Sorocea bonplandii in Southern Brazilian Forest Fragments: AFLP Diversity

To analyse possible genetic erosion due to fragmentation in the Brazilian Atlantic Forest ecosystem, we investigated the genetic diversity within and among one large and six small populations of one of the key species of this ecosystem, Sorocea bonplandii, using AFLP analyses of 468 plants. Eight primer pairs yielded 299 polymorphic fragments for analysis. S. bonplandii was characterized by an unusually high genetic diversity within the species and also within individual populations, around 94% of the total genetic diversity occurred within populations. Genetic distances between populations were low in spite of extensive fragmentation. Genetic distance was significantly correlated with geographical distances between fragments, but these differences may have existed before fragmentation. Our results have direct implications for sustainable management of S. bonplandii, indicating that conservation strategies might be based on a random sample of trees taken throughout the Atlantic forest. However, the minimum population size required for maintaining the huge genetic diversity of this species is unknown. In order to establish a sustainable management plan for the species, further ecological studies are needed.