Solving the mystery of the most misidentified marine organism in the world

The rough periwinkle, Littorina saxatilis, presents a remarkable phenotypic variation, resulting in an enormous challenge for taxonomists. In the last two decades, the combination of genetics and ecological studies made this species one of the best-characterized models for studying adaptation and speciation in the intertidal realm. The evidence collected so far suggests that two divergent forms (or ecotypes) found across different geographic regions evolved in parallel from local populations under similar divergent selective pressures (crab predation and wave exposure). Although numerous putative barrier loci between ecotypes have been identified, until recently, the paucity of information concerning the distribution of these loci across the genome precluded inference concerning the genomic architecture of reproductive isolation. Benefiting from a collective research effort, we identified several clusters of SNPs in relatively high LD, compatible with suppressed-recombination patterns within genomic regions encompassed by chromosomal inversions. In this seminar, I will present these results, as well as ongoing work trying to understand the link between these inversions and adaptive phenotypes in order to decipher their evolutionary significance in parallel ecotype divergence. We hypothesise that inversions provide evolutionary solutions to face multiple and highly variable selective pressures in intertidal species. Ultimately, we hope to understanding when and where these putative ‘ADAPTIVE CASSETTES’ were assembled and transferred among populations or species, how they evolve, and their role in species’ response to anthropogenic change in marine ecosystems.

Rui Faria is an evolutionary biologist primarily focused on the study of adaptation and speciation. In particular, he is interested in understanding the role of chromosomal rearrangements in adaptation and in the emergence of new species. Rui Faria joined CIBIO >20 years ago to work on population genetics of fish under the supervision of Paulo Alexandrino, where he got his PhD. Facing a growing interest in speciation, in 2007 he started a postdoc under the supervision of Arcadi Navarro at the Institute of Evolutionary Biology (Barcelona, Spain), to study the role of chromosomal rearrangements in species divergence. After ~3 years, he returned to CIBIO to lead a research project on the genetic mechanisms of parallel evolution and ecological speciation in flat periwinkles (marine snails). In order to further broaden his skills in evolutionary biology, in 2016 Rui Faria moved to the Univ. of Sheffield (UK) to work with Roger Butlin on the evolutionary significance of chromosomal inversions in Littorina saxatilis. He returned to CIBIO in 2019, joining the research group led by Miguel Carneiro (EVOLGEN), where he is now starting to investigate the role of inversions on adaptation to environmental change.

 

[Host: Miguel Carneiro, EVOLGEN]