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Fish stocking has been utilized for over a century to offset extirpations or declines in abundance of many native species. These historical declines and hatchery contributions have led to uncertainty surrounding whether many contemporary populations are native, introgressed with hatchery sources, or entirely of hatchery origin. Such uncertainty is problematic for the conservation of native biodiversity as it hampers management agencies' ability to prioritize the conservation of indigenous locally adapted populations. Fortunately, genetic and genomic tools have allowed researchers to investigate these questions, often through the use of clustering or assignment approaches that are predicated on identifiable and consistent divergence between native populations and hatchery sources. Here, we apply these methods to restriction-site associated DNA (RAD) data from 643 brook trout (Salvelinus fontinalis) originating from 13 wild populations and an exogenous hatchery strain to investigate the extent of historical extirpations, hatchery contributions, and processes affecting population structure in a small area of the previously unglaciated Driftless Area of Wisconsin, USA. The results from these analyses suggest that wild populations in this region are genetically distinct even at small spatial scales, lack strong hydrologically associated population structure, rarely exchange gene flow, and have small effective population sizes. Furthermore, wild populations are substantially diverged from known hatchery strains and show minimal evidence of introgression in clustering analyses. However, we demonstrate through empirically informed simulations that distinct wild populations may potentially be hatchery-founded and have since diverged through rapid genetic drift. Collectively, the apparent lack of hydrological population structure and potential for rapid drift in the Driftless Area suggest that many native populations may have been historically extirpated and refounded by stocking events. If this is the case, then commonly used genomic clustering methods and their associated model selection criteria may result in underestimation of hatchery introgression in the face of rapid drift.
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A new genomic resource to enable standardized surveys of SNPs across the native range of brook trout ( Salvelinus fontinalis )
Abstract Understanding how genetic diversity is distributed across spatiotemporal scales in species of conservation or management concern is critical for identifying large‐scale mechanisms affecting local conservation status and implementing large‐scale biodiversity monitoring programmes. However, cross‐scale surveys of genetic diversity are often impractical within single studies, and combining datasets to increase spatiotemporal coverage is frequently impeded by using different sets of molecular markers. Recently developed molecular tools make surveys based on standardized single‐nucleotide polymorphism (SNP) panels more feasible than ever, but require existing genomic information. Here, we conduct the first survey of genome‐wide SNPs across the native range of brook trout (Salvelinus fontinalis), a cold‐adapted species that has been the focus of considerable conservation and management effort across eastern North America. Our dataset can be leveraged to easily design SNP panels that allow datasets to be combined for large‐scale analyses. We performed restriction site‐associated DNA sequencing for wild brook trout from 82 locations spanning much of the native range and domestic brook trout from 24 hatchery strains used in stocking efforts. We identified over 24,000 SNPs distributed throughout the brook trout genome. We explored the ability of these SNPs to resolve relationships across spatial scales, including population structure and hatchery admixture. Our dataset captures a wide spectrum of genetic diversity in native brook trout, offering a valuable resource for developing SNP panels. We highlight potential applications of this resource with the goal of increasing the integration of genomic information into decision‐making for brook trout and other species of conservation or management concern.
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- Award ID(s):
- 1652278
- PAR ID:
- 10499110
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Molecular Ecology Resources
- ISSN:
- 1755-098X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1111/1755-0998.13853
