SPECREP

How predictable is evolution? Do species respond in the same way to similar environmental pressures? The question of repeatability is crucial in evolutionary biology because it can inform on the mechanisms generating and shaping diversity and can shed light on how organisms might react in the face of future changes. We propose to investigate the repeatability of the genomic and phenotypic bases of speciation, the ultimate process underlying biodiversity. To this end, we take advantage of the exceptional potential for natural replication offered by a ‘suture zone’, a narrow region where multiple racial hybrid zones of butterfly species coincide at a strong environmental gradient between the Amazon and the Andes. For eight of these species, we will: (1) quantify divergence for ecologically important traits (wing colour pattern, sexual pheromones, microhabitat, hostplants) and measure the contribution of these traits to reproductive isolation, using experimental approaches; (2) quantify genome-wide patterns of divergence and the genetic architecture of reproductive isolation, based on genomic scans; (3) identify the genetic bases of trait variation, using genetic mapping (crosses and association mapping) and genome-wide gene annotation on two de novo assembled reference genomes; (4) analyse the relationships between divergence and reproductive isolation in a comparative framework and compare our findings with those obtained in other Lepidoptera, particularly mimetic butterflies Our unique combination of cutting-edge methods in a comparative framework will provide important advances in our understanding of speciation by revealing general patterns and singularities in the speciation process. The project will also provide a large-scale test of existing models of speciation and will contribute to identifying the genomic regions underlying key phenotypic traits.