Abstract
Broad-scale patterns of genetic diversity for Brook Trout Salvelinus fontinalis remain poorly understood across their endemic range in the eastern United States. We characterized variation at 12 microsatellite loci in 22,020 Brook Trout among 836 populations from Georgia, USA, to Quebec, Canada, to the western Great Lakes region. Within-population diversity was typically lower in the southern Appalachian Mountains relative to the mid-Atlantic and northeastern regions. Effective population sizes in the southern Appalachians were often very small, with many estimates less than 30 individuals. The population genetics of Brook Trout in the southern Appalachians are far more complex than a conventionally held simple “northern” versus “southern” dichotomy would suggest. Contemporary population genetic variation was consistent with geographic expansion of Brook Trout from Mississippian, mid-Atlantic, and Acadian glacial refugia as well as differentiation among drainages within these broader clades. Genetic variation was pronounced among drainages (57.4% of overall variation occurred among 10-digit hydrologic unit code [HUC10] units or larger units) but was considerable even at fine spatial scales (13% of variation occurred among collections within HUC12 drainage units). Remarkably, 87.2% of individuals were correctly assigned to their collection of origin. While comparisons with fish from existing major hatcheries showed impacts of stocking in some populations, genetic introgression did not overwhelm the signal of broad-scale patterns of population genetic structure. Although our results reveal deep genetic structure in Brook Trout over broad spatial extents, fine-scale population structuring is prevalent across the southern Appalachians. Our findings highlight the distinctiveness and vulnerability of many Brook Trout populations in the southern Appalachians and have important implications for wild Brook Trout management. To facilitate application of our findings by conservation practitioners, we provide an interactive online visualization tool to allow our results to be explored at management-relevant scales.
| Original language | English |
|---|---|
| Pages (from-to) | 127-149 |
| Number of pages | 23 |
| Journal | Transactions of the American Fisheries Society |
| Volume | 151 |
| Issue number | 2 |
| DOIs | |
| State | Published - Mar 2022 |
Funding
We would like to express our sincere gratitude to the many technicians, collaborators, personnel, and volunteers that helped collect or coordinate the tissue samples used in this study: Brendan Annett (Waquoit Bay National Estuarine Research Reserve), William Ardren (U.S. Fish and Wildlife Service [USFWS], Abernathy Fish Technology Center), Jim Atkinson (National Park Service [NPS], Shenandoah National Park), Aaron Aunins (USGS, EESC), Andy Burt (Ohio Department of Natural Resources), Larry Claggett (Wisconsin Department of Natural Resources), Joe Clark (USGS, Southern Appalachian Field Branch at the University of Tennessee), Bruce Connery (NPS, Acadia National Park), Scott Cornett (New York State Department of Environmental Conservation [NYSDEC]), David Demarest (NPS, Shenandoah National Park), Mike Eackles (USGS, EESC), Robert Fawcett (New Hampshire Fish and Game Department), Dylan Fraser (University of Laval), Merry Gallagher (Maine Department of Inland Fisheries and Wildlife), Frank Getchell (Trout Unlimited), Pat Hamilton (New Jersey Division of Fisheries and Wildlife), Shannon Julian (USGS, Leetown Science Center), Bill Kalishek (Iowa Department of Natural Resources), Rich Kirn (Vermont Fish and Wildlife Department), Matt Kline (University of Maryland Center for Environmental Science [UMCES], Appalachian Laboratory), Mike LaVoie (Cherokee Fisheries and Wildlife Management), Lori Maloney (Tioga County Conservation District), David Manski (NPS, Acadia National Park), Pat Mazik (West Virginia University), Roger McPherson (Clarion University of Pennsylvania), Gonzalo Mendez (U.S. Forest Service [USFS] at the University of Massachusetts Amherst), Steve Moore (NPS, Great Smoky Mountains National Park), Keith Nislow (USFS at the University of Massachusetts Amherst), Jack Oelfke (NPS, Isle Royale National Park), Tom Oldham (West Virginia Department of Natural Resources), Todd Petty (West Virginia University), Richard Preall (NYSDEC), Joanne Printz (Virginia Polytechnic Institute and State University), Andrew Roach (NPS, Catoctin Mountain Park), Dan Sinopoli (Burnt Hills-Ballston Lake High School, New York), Jay Stauffer (Pennsylvania State University), Wendylee Stott (USGS, Great Lakes Science Center), John Switzer (USGS, Leetown Science Center), Dianne Timmins (New Hampshire Fish and Game Department), Chris van Maaren (NYSDEC), James Voigt (NPS, Catoctin Mountain Park), Dave Weller (USGS, EESC), Derek Wiley (UMCES, Appalachian Laboratory), Joe Williams (Virginia Department of Game and Inland Fisheries), Alastair Wilson (University of Guelph), Jeb Wofford (NPS, Shenandoah National Park), and Colleen Callahan Young (USGS, EESC). (The affiliation of the individual at the time of fish collection is indicated in parentheses next to the name and may not be the current affiliation of that individual.) We apologize to anyone we may have inadvertently missed who helped during the many years this study has been ongoing. We thank Mike Eackles and Robin Johnson (USGS, EESC) for help with laboratory work. Shannon Julian and Colleen Callahan Young (both formerly at the USGS, Leetown Science Center) were also instrumental with laboratory work and data collection. We appreciate the numerous helpful conversations we have had with others as we developed the manuscript, especially our dialogues with members of the Trout Technical Committee, American Fisheries Society Southern Division. David Demarest (NPS, Shenandoah National Park) and Larry Kallemeyn (USFWS, National Archives) provided useful information on historical Brook Trout stocking in the region. We thank Shannon L. White (USGS, EESC) for her thorough and helpful assistance with revisions. We have included the late Tim King as a coauthor, as he played a critical role in the design and execution of the project; without his vision and ambition, this effort would not have been possible. The participation of E.M.H. was supported in part by the Virginia Agricultural Experiment Station under the Hatch Program of the U.S. Department of Agriculture’s National Institute of Food and Agriculture. Funding was provided by the North Carolina Wildlife Resources Commission to USGS to support the genotyping and analysis of many of the samples. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. There is no conflict of interest declared in this article. We would like to express our sincere gratitude to the many technicians, collaborators, personnel, and volunteers that helped collect or coordinate the tissue samples used in this study: Brendan Annett (Waquoit Bay National Estuarine Research Reserve), William Ardren (U.S. Fish and Wildlife Service [USFWS], Abernathy Fish Technology Center), Jim Atkinson (National Park Service [NPS], Shenandoah National Park), Aaron Aunins (USGS, EESC), Andy Burt (Ohio Department of Natural Resources), Larry Claggett (Wisconsin Department of Natural Resources), Joe Clark (USGS, Southern Appalachian Field Branch at the University of Tennessee), Bruce Connery (NPS, Acadia National Park), Scott Cornett (New York State Department of Environmental Conservation [NYSDEC]), David Demarest (NPS, Shenandoah National Park), Mike Eackles (USGS, EESC), Robert Fawcett (New Hampshire Fish and Game Department), Dylan Fraser (University of Laval), Merry Gallagher (Maine Department of Inland Fisheries and Wildlife), Frank Getchell (Trout Unlimited), Pat Hamilton (New Jersey Division of Fisheries and Wildlife), Shannon Julian (USGS, Leetown Science Center), Bill Kalishek (Iowa Department of Natural Resources), Rich Kirn (Vermont Fish and Wildlife Department), Matt Kline (University of Maryland Center for Environmental Science [UMCES], Appalachian Laboratory), Mike LaVoie (Cherokee Fisheries and Wildlife Management), Lori Maloney (Tioga County Conservation District), David Manski (NPS, Acadia National Park), Pat Mazik (West Virginia University), Roger McPherson (Clarion University of Pennsylvania), Gonzalo Mendez (U.S. Forest Service [USFS] at the University of Massachusetts Amherst), Steve Moore (NPS, Great Smoky Mountains National Park), Keith Nislow (USFS at the University of Massachusetts Amherst), Jack Oelfke (NPS, Isle Royale National Park), Tom Oldham (West Virginia Department of Natural Resources), Todd Petty (West Virginia University), Richard Preall (NYSDEC), Joanne Printz (Virginia Polytechnic Institute and State University), Andrew Roach (NPS, Catoctin Mountain Park), Dan Sinopoli (Burnt Hills‐Ballston Lake High School, New York), Jay Stauffer (Pennsylvania State University), Wendylee Stott (USGS, Great Lakes Science Center), John Switzer (USGS, Leetown Science Center), Dianne Timmins (New Hampshire Fish and Game Department), Chris van Maaren (NYSDEC), James Voigt (NPS, Catoctin Mountain Park), Dave Weller (USGS, EESC), Derek Wiley (UMCES, Appalachian Laboratory), Joe Williams (Virginia Department of Game and Inland Fisheries), Alastair Wilson (University of Guelph), Jeb Wofford (NPS, Shenandoah National Park), and Colleen Callahan Young (USGS, EESC). (The affiliation of the individual at the time of fish collection is indicated in parentheses next to the name and may not be the current affiliation of that individual.) We apologize to anyone we may have inadvertently missed who helped during the many years this study has been ongoing. We thank Mike Eackles and Robin Johnson (USGS, EESC) for help with laboratory work. Shannon Julian and Colleen Callahan Young (both formerly at the USGS, Leetown Science Center) were also instrumental with laboratory work and data collection. We appreciate the numerous helpful conversations we have had with others as we developed the manuscript, especially our dialogues with members of the Trout Technical Committee, American Fisheries Society Southern Division. David Demarest (NPS, Shenandoah National Park) and Larry Kallemeyn (USFWS, National Archives) provided useful information on historical Brook Trout stocking in the region. We thank Shannon L. White (USGS, EESC) for her thorough and helpful assistance with revisions. We have included the late Tim King as a coauthor, as he played a critical role in the design and execution of the project; without his vision and ambition, this effort would not have been possible. The participation of E.M.H. was supported in part by the Virginia Agricultural Experiment Station under the Hatch Program of the U.S. Department of Agriculture’s National Institute of Food and Agriculture. Funding was provided by the North Carolina Wildlife Resources Commission to USGS to support the genotyping and analysis of many of the samples. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. There is no conflict of interest declared in this article.
| Funders |
|---|
| Clarion University of Pennsylvania |
| North Carolina Wildlife Resources Commission |
| New York State Department of Environmental Conservation |
| U.S. Forest Service-Retired |
| University of Tennessee, Knoxville |
| Université Laval |
| Pennsylvania State University |
| University of Guelph |
| West Virginia State University |
| Wisconsin Department Natural Resources |
| Virginia Department of Game and Inland Fisheries |
| Maine Department of Inland Fisheries and Wildlife |
| University of Maryland Center for Environmental Science |