Diversidade genética, estrutura populacional e história demográfica em Dipteryx alata Schreb (Leguminosae)

Abstract

Phylogeography is an integrative field of science that aims to study the geographic distribution of lineages at the species level or among closely related species, using genetic information. The field has developed methods that allow testing biogeographic hypotheses, describing the evolution of reproductive isolation, and inferring processes responsible for the origin, distribution, and maintenance of biodiversity. Baru (Dipteryx alata) is a tree plant that belongs to the legume family and is widely distributed in the Brazilian Cerrado, covering eleven states and the Federal District. From a genetic point of view, baru populations are structured and present low levels of diversity. These patterns seem to be explained by the distribution restriction that occurred during the last glacial followed by expansion, however, there are still gaps in knowledge about the dynamics of lineage diversification during the expansion process throughout the Cerrado. In this context, nuclear and chloroplast DNA sequences from 296 individuals widely distributed in the Cerrado were used to combine phylogeographic analyzes with ecological niche modeling to elucidate the diversification processes of D. alata lineages that resulted in the current diversity pattern observed in the species. Our results reinforce that D. alata populations present low diversity and significant levels of genetic structure. These patterns appear to be the result of a reduction in occurrence during the last glacial maximum, with maintenance of a stable area covering the southwest and central west of the Cerrado, followed by expansion to the southeast, east and northeast regions during the middle Holocene. In this context, populations located in the southwest and west regions of the Cerrado appear to represent the oldest lineages of D. alata.