Abstracts (first author)
Assessing patterns of hybridization between North Atlantic eels using Genome-Wide Single Nucleotide Polymorphisms generated by RAD-Sequencing
Hybridization is an important issue in evolutionary biology and conservation. We investigate the dynamics of introgressive hybridization in North Atlantic eels, the European eel (Anguilla anguilla) and its sister species the American eel (Anguilla rostrata). The two North Atlantic eels occupy a broad range of habitats from Morocco to Iceland in the eastern Atlantic and from the Caribbean to Greenland in the western Atlantic, respectively. Despite such a wide non-overlapping geographic distribution, both species spawn in partial sympatry in the remote Sargasso Sea, in a migration of over 5,000 km for the European eel and 2,000 km for the American eel, which still represent to this day one of the enigmas of the animal kingdom. Spawning grounds of both species overlap in space and time, setting the stage for interbreeding. Previous studies have pointed to the existence of hybrids limited to one particular location, Iceland, although markers used did not allow clarification of their hybrid status. In our study, diagnostic species-specific single nucleotide polymorphisms (SNPs) are developed using a RAD-sequencing approach, which is a reduced representation genome sequencing method. After generating and aligning over 8000 sequence read per individual, a total of 3,348 diagnostic SNP (FST> 0.95) were identified. 96 of of those loci were selected to design a low-density array, at which we genotyped 159 eels from Iceland and 29 eels from Faroe Islands. The study was supplemented with the analysis of 94 larvae (49 European and 45 American eel) collected in the Sargasso Sea. Our study reveals high levels of hybridization in Iceland mostly consisting of F1 hybrids but backcrosses (A. anguilla x hybrid) are also observed. In comparison, no hybrids are observed in the closely-located Faroe Islands.