The divergence between lineages may occur not only by the disruption of gene flow due to geographical barriers, but also under ongoing gene flow in lineages adapted to contrasting biotic or abiotic conditions (ecological speciation). Closely related hybridizing species represent an unique opportunity to raise information on the ecological speciation process. In such systems, local adaptation to contrasting conditions can lead to speciation by either reducing mating possibilities between phenotypically divergent lineages or by decreasing hybrids performance. In this project, we aim at investigating the importance of adaptive mechanisms for the speciation of Epidendrum fulgens and E. puniceoluteum, despite high interespecific gene flow. Moreover, we aim to evaluate the importance of adaptive introgression in genes associated to tolerance to high levels of salinity, flooding, and lack of soil nutrients for the species survival in the restinga. E. fulgens and E. puniceoluteum are closely related species that hybridize in sympatric areas along the restinga in southern and southeastern Brazil. Because they are associated to contrasting adjacent habitats, the hypothesis of ecological speciation is plausible and may have promoted positive selection in coding regions and gene expression variance. Here, we will employ genomic data from RNA sequencing (RNA-seq) to investigate the genomic basis of the ecological speciation process between these species. We will also validate gene expression data thought quantitative PCRs, and interpret results based on edaphic conditions. Furthermore, we will isolate SNP markers from RNA-seq data to test alternative speciation scenarios. Although the Tropics harbor most part of biodiversity, we still lack information on the role of selection in the speciation processes and we depend on the emergence of model groups in which previous ecological and genetic information might guide sampling design and hypotheses formulation. Investigating the ecological speciation in this model group will be fundamental to improve our understanding on the role of natural selection in the origin of neotropical species and on the mechanisms underlying the evolution and maintenance of reproductive barriers between species despite interspecific gene flow.
News published in Agência FAPESP Newsletter about the scholarship: