Lamprey genotypes predispose maturation timing phenotypes in coastal and interior river basins

Previous studies have identified different maturation ecotypes for Pacific lamprey (Entosphenus tridentatus). Identification of these ecotypes was based on association of candidate genotypes at marker Etr₄64 with lamprey phenotype (ovary mass). More evidence is needed to validate the association of the candidate genotypes with the timing of sexual maturation. Here, we genotyped Etr₄64 in adult lamprey from coastal and interior watersheds and tested whether the genotypes were associated with maturation phenotypes. Coastal lamprey were predominately of the ocean-maturing (ocean) genotype, whereas interior lamprey were primarily of the stream-maturing (stream) genotype. Radio tagged coastal lamprey of the ocean genotype spawned within the collection year, whereas the stream genotype spawned the following year. Similarly, captive-held interior lamprey of the ocean genotype matured earlier relative to the stream genotype. However, the maturation schedule for both genotypes in interior lamprey was protracted relative to coastal lamprey. These results validate the association between the candidate genotypes and maturation timing in lamprey and suggest that ecotype names should be refined to include geography and maturation timing (i. e. , coastal-early, coastal-late, interior-early, and interior-late).