COS 21-4 - CANCELLED - Identifying cryptic ecological divergence of Lake trout (Salvelinus namaycush), and adaptive introgression in Mistassini Lake, Canada

Background/Question/Methods

Identifying the ecologically distinct lineages across various habitats can aid in the understanding of adaptive evolution. However, identifying the lineages is a challenge in an admixed population. The lake trout represents a model species for studying ecological divergence, and a previous study showed a weak correlation between genetic clusters and morpho-ecological clusters in Mistassini Lake, Quebec’s largest natural lake. To disentangle the ecologically distinct lineages in Mistassini Lake, we investigated the ancestry of pure and admixed individuals based on the population-level low coverage whole genome sequencing (lcWGS) data.

Results/Conclusions

We reveal five ecological and morphological divergent ecotypes in Mistassini Lake. One profundal ecotype shows bright body coloration, a slower growth rate while the four pelagic ecotypes show dark body coloration and large body size. We identified the candidate genes that are responsible for the ecological divergence, and its consequences for the introgression. We found strong evidence of extensive introgression in the candidate genes. Demographic analysis shows that historical and contemporary hybridization may contribute extensively to the introgression of the adaptive variants across ecotypes. This study provides insight into the importance of ecomorphological divergence and subsequent adaptive introgression in the diversification of sympatric ecotypes.