Patterns and processes of genomic divergence along the speciation continuum in two recent evolutionary radiations: a multidisciplinary and integrative approach. (DIVERGEN)

Spanish National Plan for R+D+i (CGL2014-54671-P). PI: Joaquín Ortego. 2015-2018.

Understanding the processes that generate and maintain biological diversity and how these interact with landscape history is a central theme in biogeography and evolutionary biology. Information across the whole spatiotemporal spectrum at which these processes take place is also necessary to preserve biodiversity at its different levels, from ecosystems and communities to unique intraspecific evolutionary processes. The study of recent evolutionary radiations is particularly attractive to address these questions because the signatures of such events have not been fully erased by time and thus provide the potential to infer processes from patterns in genetic data. The goal of this project is to integrate next generation sequencing (NGS) techniques, detailed phenotypic information and spatial modelling to unravel the factors promoting recent evolutionary radiations and infer the underlying evolutionary processes behind spatial patterns of genetic, ecological and phenotypic divergence. This project will use as model systems two species complexes of montane grasshoppers of the genera Omocestus (subgenus Dreixius) and Chorthippus (subgenus Glyptobothrus, group Binotatus) to understand the consequences of past climatic changes and the role of geography, environment and adaptation processes in 1) species diversification phenomena and 2) regional and local intraspecific patterns of genomic variation. Thus, we aim to track the organism diversification process from those stages that shape early genetic and phenotypic divergence at small spatial scales through the incipient speciation end, both of which are well represented in these species complexes composed by several recently diverged taxa but with different ecological and habitat requirements. In particular, the specific objectives of this project are: 1.1) Generating large genomic datasets (10000-20000 loci) and obtaining detailed phenotypic information to reach an unprecedented resolution in the delineation of evolutionary independent lineages and evaluate how the obtained inferences are impacted by different subsets of loci (outliers vs. non-outliers) and the potential confounding effects of introgressive hybridization; 1.2) Analysing the factors (geographic isolation mediated by past climate changes vs. ecological divergence) driving observed patterns of diversification. At a smaller spatiotemporal scale this project will 2.1) analyse contemporary hybridization among recently diverged sympatric/parapatric taxa to understand the relative importance of geographic overlap, selection by environment and reproductive barriers in shaping the location and extent of hybrid zones; 2.2) Study the demographic history within each delineated species/lineage using a landscape genomic approach to understand whether taxa with different ecological requirements differ in their responses to geography and environment (e.g. habitat stability defined by past climate vs. contemporary patterns of dispersal); 2.3) Disentangling the effects of geography and environment (“isolation-by-environment”) in observed patterns of population divergence and local adaptation processes. Overall, the research results derived from this project will greatly contribute to increase our knowledge on the evolutionary dynamics of species across a big portion of the organismal diversification spectrum.