Directional selection against different life histories in the Arctic lamprey (Lethenteron camtschaticum): Identification by microsatellite analysis

To understand the selective forces promoting life history evolution in lampreys, footprints of natural selection were identified using the hitchhiking mapping approach for microsatellite loci. To achieve the objective, the Arctic lamprey (Lethenteron camtschaticum), including anadromous and recently derived landlocked-fluvial populations, were targeted. Seven microsatellites were genotyped and subjected to population genetic analyses and outlier tests. The results indicated that a significant signature of directional selection could be detected in one microsatellite locus (Lspn013). Discrepancies in allelic frequencies of Lspn013 were remarkable between anadromous and landlocked-fluvial populations, leading to high population genetic divergence between them. Based on a homology search, Lspn013 was estimated to be located near the vasotocin precursor gene, which plays an important role in osmoregulation. Life history differences in lampreys have resulted from habitat difference in adult phase, which have probably led to recent natural selection on the gene responsible for osmoregulatory functions.