Adaptation during biogeographic transitions from the Cerrado to the Caatinga: evolutionary parallelism and idiosyncrasies in independent clades of genus Cereus (Cactaceae)

Abstract

Here, we will use a genomic and ecological approach to test the hypothesis of parallel natural selection associated with the historical transition from the Cerrado to the Caatinga in two clades of genus Cereus (Cactaceae), with different ages, habitats, and phylogenetic fuse. Considering the distinct climatic and edaphic conditions between the Cerrado and Caatinga biomes, the main assumption is that biogeographic transitions involving these biomes must have been associated with adaptive changes and niche evolution, which usually occur in this type of event. The strategy for data collection involves obtaining genetic data (transcriptomes and complete low-coverage genomes) and ecological data (selected phenotypes and ecological niche modeling) for species from two Cereus clades, namely: a) Jamacaru clade (C. jamacaru ssp. jamacaru and C. jamacaru ssp. calcirupicola); b) clade D (C. albicaulis and C. mirabella); in addition to external groups for each clade. Adopting this experimental design and several statistical approaches, it will be possible to test whether there are common signatures of natural selection in the independent transitions from the Cerrado to the Caatinga experienced by the genus Cereus, which could indicate evolutionary parallelism at the level of nucleotide sites, genes, or metabolic pathways. In addition, as the target clades have particularities in relation to occupied niches, it will also be possible to investigate signatures of idiosyncratic adaptations. (AU)