História biogeográfica e padrões filogenéticos de Erythroxylum P. Browne no Brasil

Abstract

Numerous studies have sought to understand the relationship between plant distribution and occupation time in different vegetation types. In order to analyze this relationship, we chose the genus Erythroxylum to elucidate the biogeographic history, the phylogenetic relationships between the Asian, neo and paletropical species and the expansion of the area of occurrence in Brazilian territory. The present study aimed to elucidate the biogeographic history, the phylogenetic relationships between the Asian, neo and paletropical species of the genus Erythroxylum and the expansion of the area of occurrence in Brazilian territory. We test the hypothesis that tropical species of wide distribution have been more time on the action of speciation processes, therefore they present high phylogenetic diversity. In order to better understand how the climatic oscillations influenced the paleodistribution in the Brazilian territory and the occupation of areas in environments of dry and humid climates, we generated potential niche models for three climatic scenarios: current climate, last glacial maximum (~ 21 kyr BP) and (~ 130 kyr BP) for 11 species of the genus. To evaluate the areas of occurrence, delimiting areas with greater richness and phylogenetic relationships between species, we performed molecular analyzes and a model in Akaike criteria using richness as response variable. For the elaboration of a phylogenetic tree we obtained sequences for two markers (one plastidial and one nuclear) for 41 species of Erythroxylum occurring in the Neotropics, Africa and Asia. We obtained as results of the niche models in paleoenvironmental scenario four distinct patterns of expansion and contraction of occurrence areas: a humid subtropical, a tropical exclusively humid, one distributed in humid and seasonally dry climates and one exclusively seasonally dry. As a result of the molecular analyzes, we obtained eight clades that allowed to infer the existence of two lineages one neo and paleotropical, and another Asian. It was not possible to observe spatial segregation between the clades generated. We conclude that the proposed patterns for using niche modeling did not delineate distinct clades. In Brazilian territory, the species occur preferentially in seasonally dry conditions and the largest centers of wealth are in the Northeast and Southeast of the country. Species of the genus had recent speciation which may have favored the wide distribution currently observed.