Phylogeny, biogeography and diversification of cacti in South America

Abstract

The global expansion of arid and semiarid habitats is often associated with climate changes that occurred during the Miocene and Pleistocene. Despite the relevance of these climatic events for the diversification of plants in xeric (dry) environments, few studies have been conducted related to the role of the expansion of aridity as a mechanism of diversification in South America. Besides the expansion of aridity, biotic factors may be involved with the diversification of taxon associated with xeric habitats, as observed in previous studies within Cactaceae family. Due to the recent diversification of this family, molecular phylogenies that used few molecular markers were not able to distinguish the relationship within its main clades. A reasonable strategy to obtain higher accuracy and resolution in phylogenetic inferences is to employ genomic data combined with coalescence phylogenetic approaches. This project aims to investigate biotic and abiotic factors associated with the diversification of the tribe Cereeae and to identify ecological and evolutionary patterns that allow us to test hypotheses about the diversification of taxa that inhabit xeric areas in South America. Here we will employ next-generation sequencing methods and new phylogenetics approaches in order to perform historical biogeography inferences and tests of association between biotic and abiotic variables with shifts in diversification rates in the tribe Cereeae. (AU)