Caucasian treasure: genomics sheds light on the evolution of half-extinct Sevan trout, Salmo ischchan, species flock

Five ecologically and phenotypically divergent ecomorphs/young species of the genus Salmo are known from a landlocked alpine lake in the Caucasus, Lake Sevan, that was isolated ca. 20 000 years ago by a waterfall. It is an unprecedented example of sympatric diversification within a species-rich lineage with the predominant mode of speciation being allopatric. The main driver of diversification within Sevan trout was spawning resource partitioning. Four lacustrine ecomorphs with different temporal-spatial spawning strategies and divergent phenotypes evolved along with a fifth ecomorph, brook trout, inhabiting the tributaries. Unfortunately, the Sevan trout diversity was almost destroyed by human activity, with two ecomorphs becoming extinct in the 1980s. We performed reconstruction of the evolutionary history of Sevan trouts based on NGS sequencing of both contemporary and aDNA (∼ 50 y.o. dried scales) of all Sevan trout ecomorphs. Our study of complete mitogenomes along with nuclear SNP...