Genes That Predict Large-Bodied Pacific Lamprey Go the Distance: An Adaptive Context for Conservation Management Applications

Elucidation of genetic mechanisms underpinning migratory behavior could help predict how changes in genetic diversity may affect the future spatio-temporal distribution of a migratory species.  This ability would benefit conservation of one such declining species, anadromous Pacific lamprey (Entosphenus tridentatus).  Nonphilopatric migration of adult lamprey has homogenized population-level neutral variation, but has maintained adaptive variation that differentiates groups based on geography, run-timing, and adult body form.  To investigate causes for this adaptive divergence, we examined 647 adult lamprey sampled at a fixed location on the Columbia River and radio-tracked during their subsequent upstream migration. We tested whether genetic variation (96 neutral and adaptive single nucleotide polymorphism markers previously identified from a genome-wide association study) was associated with migration distance, migration timing, or morphology.  Three adaptive markers were strongly associated with morphology, and one marker was also significantly correlated with upstream migration distance.  Genes physically linked with these markers plausibly influence differences in body size, which is also consistently associated with migration distance in Pacific lamprey. Lamprey conservation implications include the potential to predict an individual’s upstream fate based on its genotype.  More broadly, the results suggest a genetic basis for intrapopulation variation in migration distance in other migratory species.