Geology topics

David Rowe

Publications and source records attributed to David Rowe.

4 recordsLinked to original sources

USGS2021

Broadscale population structure and hatchery introgression of Midwestern brook trout: Midwestern brook trout population genetics

Brook Trout Salvelinus fontinalis have faced significant declines throughout their native range and have been stocked in Midwestern waters since the late 1800s to offset such losses. Several studies have investigated the genetic effects of these stockings, but these efforts have been confined to relatively small spatial scales. In this study, we compiled 8,454 Brook Trout microsatellite genotypes from 188 wild Midwestern populations and 26 hatchery strains to provide novel insights of broadscale population structure, regional patterns of genetic diversity, and estimates of hatchery introgression for inland Wisconsin populations. Our results indicate high levels of differentiation among our study populations, a lack of hydrological population structuring, lower estimates of genetic diversity in the Driftless Area, and that hatchery introgression has been largely confined to regions of inland Wisconsin that have been heavily affected by anthropogenic disturbances (i.e., the Driftless Area). We also provide evidence that populations may be able to purge hatchery‐derived alleles, discuss possible mechanisms behind this phenomenon, and consider their relevance to accurate estimation of hatchery introgression. Collectively, these results summarize the genetic effects of over a century of anthropogenic disturbance on native Brook Trout populations and emphasize the importance of integrating historical data into contemporary genetic research of intensively managed species.

Iowa, Minnesota, Wisconsin↗

USGS2020

Using genetic data to estimate capture rate of Wisconsin and Leech Lake strains of Muskellunge stocked in four Wisconsin Lakes

Many inland fisheries are supported by stocking of hatchery-produced fish, and fisheries managers often face difficult decisions regarding strain selection. Stocking evaluations designed to quantify differences in strain performance provide valuable data for designing stocking programs. Here, we use genetic tools to investigate capture rate of two strains of Muskellunge stocked in Wisconsin lakes. We genotyped a total of 1,011 Muskellunge at 13 microsatellites and used data from five reference populations to assign fish stocked in four Wisconsin lakes to their strain of origin. The strains stocked in these lakes were derived from Wisconsin populations in the Upper Chippewa and Wisconsin River drainages and from Leech Lake, Minnesota. Leech Lake Muskellunge demonstrated much lower capture rates than the Wisconsin strain, but results were variable, with a 10% capture rate of Leech Lake strain fish in Lake Monona and 2% capture rate in Lake Wissota despite similar stocking rates (~25%) in both lakes. We hypothesize that the higher capture rates of Wisconsin strain Muskellunge could be due adaptative advantages of the Wisconsin strain in these waters and suggest that managers continue to stock the nearest native (i.e. Wisconsin) strain to achieve the highest return on investment. Keywords: Muskellunge, propagation, Wisconsin, Leech Lake, stocking evaluation, microsatellite, population genetics ms accepted

Wisconsin↗

USGS2020

Genetic structure of Smallmouth Bass in the Lake Michigan and Upper Mississippi River drainages relates to habitat, distance, and drainage boundaries: Smallmouth bass population genetic structure

Analysis of genetic connectivity helps to define stock boundaries and provides information on interpopulation dynamics, such as migration and spawning site fidelity. We used 16 microsatellite loci to describe the genetic population structure of 1,215 Smallmouth Bass Micropterus dolomieu from 32 sites throughout the upper Mississippi River and Lake Michigan watersheds. We found that Smallmouth Bass populations formed two genetically distinct units separated by the Mississippi River–Lake Michigan drainage boundary. Smallmouth Bass from the Lake Michigan drainage could be parsimoniously grouped into two or six genetically distinct units that largely corresponded with either river or lake habitats, while fish from the Mississippi River drainage grouped into two, six, or nine genetic units that were mostly associated with watershed boundaries. In the Lake Michigan and Mississippi River drainages, relative migration was limited between lake and river sites, suggesting that gene flow between neighboring sites with different habitat attributes can be low. Our research provides a higher‐resolution assessment of Smallmouth Bass genetic structure in a core portion of the species’ range and provides strong evidence that Smallmouth Bass populations are structured at small spatial scales that are potentially associated with habitat type. These results demonstrate the importance of evaluating genetic structure at small spatial scales and adopting management strategies that preserve genetic diversity of black bass populations at both the watershed level and the habitat level.

Michigan, Wisconsin↗

USGS2019

Isolation by a hydroelectric dam induces minimal impacts on genetic diversity and population structure in six fish species

Reduced connectivity created by artificial barriers can influence the genetic integrity of isolated subpopulations by reducing local population sizes and altering patterns of gene flow. We investigated the genetic impacts of one such barrier, the Prairie du Sac dam, Wisconsin, USA, using microsatellite data from six fish species with varying life history traits sampled above and below the dam. Contrary to many past studies in other systems, we did not detect any significant differences in genetic diversity between populations found above and below the Prairie du Sac dam. Our results also revealed low genetic differentiation ( F ST = 0–0.008) between populations above and below the dam for all species. In fact, we found that more genetic variation was partitioned among sampling years than between above and below dam populations for all but one of the species. Results from coalescent simulations designed to model our study system indicated that the genetic impacts of the dam will likely be detectable approximately 40–60 generations after the dam was constructed, and that it is possible to largely mitigate these impacts with a fish passage strategy that facilitates a migration rate of ≥ 1% between above and below dam populations. In summary, our findings suggest the genetic impacts of dams can be relatively minimal on short time scales, and that fish passage strategies can significantly reduce genetic impacts if designed appropriately.

Wisconsin↗