Isolamento de miscrossatélites, taxonomiamolecular e diversidade genética de Planthymenia (Leguminosae)

Abstract

The taxonomy of the genus Plathymenia, leguminous tree widely distributed in South America, has been much discussed since its description. In the most recent taxonomic revision of the genus, the two species originally described were considered a single species. Some years later, ecophysiological studies have demonstrated the existence of adaptive differences related to environmental differences between Atlantic Forest and Cerrado, which led researchers to consider the existence of different ecotypes between the two biomes. In the present study,microsatellite markers were developed specifically for Plathymenia and characterized in 51 individuals present in two populations sampled in areas of Cerrado. The isolated loci showed a high degree of polymorphism and were further used to investigate the occurrence of gene flow between populations present in the Atlantic Forest and Cerrado. A total of 159 individuals were sampled in two populationslocated in core areas of Cerrado, in two populations of core areas of Atlantic Forest, and in four other populations, located in ecotonal regions where the transition from one biome to another occurs. It was found that the habitat in which populations were sampled more is more related to the genetic differentiation found than the geographical distance between populations. When comparing the populations present in the core areas of Cerrado and Atlantic Forest we have found genetic differences that are consistent with the classification of individuals into two ecotypesadapted to different environmental conditions found in each of the biomes. However, high levels of gene flow were observed in the populations present in the ecotone areas, indicating that there are no mechanisms for complete reproductive isolation between the two ecotypes Plathymenia. Our results corroborate, therefore, with thelatest taxonomic revision that considers the genus Plathymenia monospecific.