Diversidade genética e ecológica de abelhas das orquídeas em diferentes formações vegetais brasileiras

Abstract

The bees of the tribe Euglossini (Apidae) perform an important role in the maintenance of Neotropical forests, as they pollinate several families of plants. The most notable aspect of orchid bees is the search for chemical compounds present in plants, by the males of this tribe. Brazil has the two humid tropical forest formations with the highest diversity of species in the world, the Amazon forest and the Atlantic forest, which, interspersed with the Cerrado domain, contain the highest biodiversity in South America. The sampling distribution of the surveys of the orchid bee fauna is not homogeneous, most areas are not even sampled. Besides the insufficient number of inventories, there is an incipiency regarding the ecological knowledge and the genetic diversity of the populations of the group. Thus, the present study aimed to investigate, based on mitochondrial (16S and COI) and nuclear (Opsin) molecular markers, the genetic diversity and structure of populations of two species that have an intimate host-parasite relationship, in this case Eulaema nigrita Lepeletier (host) and Exaerete smaragdina (Guérin) (parasite) throughout the Atlantic forest and other Brazilian formations. In association with the genetic data, assess the species richness, composition and abundance of the Euglossini bee communities in Cerrado and Amazon forest remnants present in the northeastern transition area (TN), an area in which the state of Maranhão is located. The results of Bayesian Skyline Plot (BSP) analyses, haplotype networks, neutrality tests and genetic diversity analyses based on COI gene indicate population expansion of El. nigrita and Ex. smaragdina during the Pleistocene. Our data revealed areas with high genetic diversity considered potential refugia during Pleistocene climatic ocillations in the Atlantic forest, in Pernambuco for Ex. smaragdina (Hd=0.750±0.139) and Espírito Santo for El. nigrita (Hd=1±0.272). For the latter species the highest diversity patterns (Hd=0.873) were found in the TN region and corroborating with literature data this area was associated with a potential refuge for Euglossini bees during climatic oscillations in the Pleistocene. Aligned with these data, high species richness values were found in the Cerrado (24 species) and Amazon forest (42 sp) present in the TN region. With highlights for the Reentrâncias Maranhense Environmental Protection Area of where one of the highest richness values in studies with orchid bees in Brazil was found. Both genetic (COI gene) and community structure data indicate that the northeastern transition area played an important role in the evolutionary history of orchid bees.