Paleodistribution of Neotropical species of Erythroxylum (Erythroxylaceae) in humid and dry environments

Abstract

Variation in environmental conditions during the Quaternary period served as important fi lters for the maintenance of vegetation types and for determining the composition of the current biota. We analyzed oscillations in the distributions of diff erent vegetation types in Brazil during the Quaternary period using species of the genus Erythroxylum (Erythroxylaceae) because of the vast heterogeneity of habitats in which they occur. We hypothesized that it would be possible to observe geographically distinct distribution patterns of species of Erythroxylum as a result of the climate changes that occurred during the last glacial maximum (LGM) and in the last interglacial period (LIG) of the Pleistocene. We used bioclimatic variables to elaborate distribution models of 11 species under three scenarios: the current climate, LGM, and LIG. We found four plant distribution patterns in humid and semiarid climates. During the LIG, humid patterns were restricted to northeastern and central-western Brazil, while semiarid conditions maintained plant distributions in the same regions of Brazil where they occur today, although with additionanl occurrences in the northern and central-western portions of that country. During the LGM, all distribution patterns exhibited extensions towards the coast due to the exposure of the continental shelf.