Connections and containers: Using genetic data to understand how watershed evolution and human activities influence cutthroat trout biogeography

Abstract

Species with large geographic distributions often exhibit complex patterns of diversity that can be further complicated by human activities. Cutthroat trout (Oncorhynchus clarkii) are one of the most widely distributed freshwater fish species in western North America exhibiting substantial phenotypic and genetic variability; however, fish stocking practices have translocated populations outside of their native range and may have obscured intraspecific boundaries. This study focuses on cutthroat trout populations representing three distinct evolutionary clades that are found intermixed within a contact zone between the Bonneville and upper Snake River watersheds in the western United States. We used mitochondrial and microsatellite genetic data, as well as historical stocking records, to evaluate whether populations of cutthroat trout in the contact zone are native or are introduced. We found significant genetic differentiation and fine-scale genetic population structure that was organized primarily by watershed boundaries. While we detected increased genetic diversity in some areas in close proximity to the greatest number of stocking events, the highly organized population structure both within and between areas of the contact zone indicates that the populations are native to the watersheds. Intermixing of distinct evolutionary lineages of cutthroat trout appears to be the result of historical connections between paleodrainages. Our analyses provide a context for understanding how genetic data can be used to assess the status of populations as native or introduced.

Estimating the genetic diversity of Pacific salmon and trout using multigene eDNA metabarcoding

“…Few taxonomic groups provide a better illustration of the role of genetics in the management of a nondomesticated species than North American Pacific salmon and trout ( Oncorhynchus spp.). This group of species inhabit a complex network of streams, rivers, lakes, and marine environments, and show dynamic population relationships that can change as a function of geological, hydrological, and human forces across the landscape (Eaton et al, 2018 ; Minckley et al, 1986 ). Oncorhynchus populations are among the most intensively managed nondomesticated species in North America, with widespread hatchery‐raised stocks adding additional complexity on top of native populations, and they are the focus of continuous monitoring of genetic diversity across management units (Johnson, Johnson, et al, 2019 ).…”

Genetic Assessment Reveals Population Fragmentation and Inbreeding in Populations of Brook Trout in the Laurel Hill of Pennsylvania

“…; Eaton et al. ). Because landscape characteristics often influence the dispersal patterns and population sizes of organisms (Dillane et al.…”