Population structure delineated with microsatellite markers in fragmented populations of a tropical tree, Carapa guianensis (Meliaceae)

Deforestation and selective logging in the tropics may have serious consequ ences on genetic processes in tropical tree populations, affecting long-ter m survival of a given species as well as tropical forest communities. Becau se understanding the effects of human-induced changes on genetic processes is of utmost importance in formulating sound conservation and management pl ans for tropical forest communities, we developed microsatellite or simple sequence repeat (SSR) markers for the tropical tree Carapa guianensis (Meli aceae) and assessed the polymorphism of SSRs in adult and sapling populatio ns in a large contiguous forest and in selectively logged and fragmented fo rests. The number of alleles in polymorphic loci ranged between 4 and 28. N o inbreeding was detected in saplings or adult cohorts, but the allelic ric hness was lower in the sapling cohort of the isolated fragment. Genetic dis tances, Nei's D and (delta mu)(2), and R-ST values among saplings were grea ter than among adult cohorts, suggesting restriction of gene flow due to de forestation and habitat fragmentation. These SSR loci may be used to addres s many related questions regarding the population and conservation genetics of tropical trees.