Spatial genetic structure of Manilkara maxima (Sapotaceae), a tree species from the Brazilian Atlantic forest

Habitat fragmentation may lead to spatial genetic structuring of plant populations, but the magnitude of this effect differs among species. In this study, the effects of fragmentation on spatial genetic structure of Manilkara maxima, an ecologically important tree species endemic to the Atlantic forest of southern Bahia, Brazil, were examined. To address this issue, 222 individuals were sampled across two large-forest sites (200 and 400 ha) and one site comprising eight small fragments (5, 10 and 25 ha) roughly 35 y old. Five microsatellite loci were used. In general, M. maxima exhibited limited genetic structuring within and across the sites examined. At the landscape scale, genetic structure was not shaped by isolation by distance. Within individual sites, weak to moderate genetic structure was observed for both adults and saplings, which represented pre- and post-fragmentation, respectively. Sapling genetic structure did not clearly vary among the study sites, suggesting fragmentation has not affected spatial genetic structure. High levels of migration were observed, which would help maintain genetic connectivity. Taken together, these results suggest M. maxima, a long-lived tree that naturally occurs in low densities, may have limited spatial genetic structuring both within and across forest patches.