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Brian L. Sloss

Publications and source records attributed to Brian L. Sloss.

At least 19 recordsLinked to original sources
USGS2020

Defining the need for genetic stock assignment when describing stock demographics and dynamics: An example using Lake Whitefish in Lake Michigan

Genetic stock assignment is not routinely used when describing the dynamics and demographics of individual stocks supporting mixed-stock fisheries, and capture location and timing are often used as alternative assignment methods. However, variation in stock demographics and dynamics may not be accounted for if stock assignments based on capture location or timing do not accurately reflect genetic assignments. We used Lake Whitefish Coregonus clupeaformis in Lake Michigan as a model fishery to determine whether stock mixing could undermine efforts to describe stock status when using October capture location as a proxy for genetic stock assignment. Accuracy of stock assignments based on October capture location ranged from 54% to 100% among management zones. Metrics describing length and age distributions, weight at length, fecundity, and growth varied among genetic stocks. Stock-specific metrics were typically similar between stock assignment methods (capture location versus genetics) because only one or two genetic stocks were collected in most locations and the majority of those fish were from spatially proximal stocks with similar metrics. However, more extensive mixing of Lake Whitefish stocks has been documented; thus, using capture location for stock assignment could result in incorrect conclusions regarding stock status and harvest management depending on stock composition. Ambiguity in genetic stock assignments was a problem in two management zones, where between 23% and 42% of Lake Whitefish did not assign to a specific stock with a probability of at least 0.70. In the future, using genomic techniques rather than microsatellites may provide different conclusions regarding genetic stock structure; these differences could affect the accuracy of using capture location for stock assignment. Use of capture location as a proxy for genetic stock assignment may not be warranted for all mixed-stock fisheries but may be appropriate when stock mixing is limited or is restricted to stocks with consistently similar characteristics.

Michigan, Wisconsin↗
USGS2017

Genetic structure of muskellunge in the Great Lakes region and the effects of supplementation on genetic integrity of wild populations

Muskellunge ( Esox masquinongy ) are important apex predators that support numerous recreational fisheries throughout the Great Lakes region. Declines in muskellunge abundance from historical overharvest and environmental degradation have threatened the viability of many populations and prompted significant restoration efforts that often include stocking. The goal of our study was to investigate contemporary population structure and genetic diversity in 42 populations of muskellunge sampled across the Great Lakes region to inform future management and supplementation practices. We genotyped 1896 muskellunge ( N = 10–123/population) at 13 microsatellite loci. The greatest genetic variation was between populations of Great Lakes origin and populations of Northern (inland) origin, with both groups also exhibiting significant substructure (overall F ST = 0.23). Genetic structure was generally correlated with geography; however, we only found marginal evidence of isolation by distance, likely due to high genetic differentiation among proximate populations. Measures of genetic diversity were moderate across most populations, but some populations displayed low diversity consistent with small population sizes or historical bottlenecks. Many of the populations studied displayed evidence of historic introductions and supplemental stocking, including the presence of individuals with primarily non-native ancestry as well as interlineage hybrids. Our results suggest that the historic population structure of muskellunge is largely intact across the Great Lakes region, but also that stocking practices have altered this structure to some degree. We suggest that future supplementation practices use local sources where possible, and incorporate genetic tools including broodstock screening to ensure that non-native muskellunge are not used to supplement wild populations.

Great Lakes↗
USGS2016

Validation of a side-scan sonar method for quantifying walleye spawning habitat availability in the littoral zone of northern Wisconsin Lakes

Previous research has generally ignored the potential effects of spawning habitat availability and quality on recruitment of Walleye Sander vitreus , largely because information on spawning habitat is lacking for many lakes. Furthermore, traditional transect-based methods used to describe habitat are time and labor intensive. Our objectives were to determine if side-scan sonar could be used to accurately classify Walleye spawning habitat in the nearshore littoral zone and provide lakewide estimates of spawning habitat availability similar to estimates obtained from a transect–quadrat-based method. Based on assessments completed on 16 northern Wisconsin lakes, interpretation of side-scan sonar images resulted in correct identification of substrate size-class for 93% (177 of 191) of selected locations and all incorrect classifications were within ± 1 class of the correct substrate size-class. Gravel, cobble, and rubble substrates were incorrectly identified from side-scan images in only two instances (1% misclassification), suggesting that side-scan sonar can be used to accurately identify preferred Walleye spawning substrates. Additionally, we detected no significant differences in estimates of lakewide littoral zone substrate compositions estimated using side-scan sonar and a traditional transect–quadrat-based method. Our results indicate that side-scan sonar offers a practical, accurate, and efficient technique for assessing substrate composition and quantifying potential Walleye spawning habitat in the nearshore littoral zone of north temperate lakes.

Wisconsin↗
USGS2016

Diet overlap and predation between largemouth bass and walleye in Wisconsin lakes using DNA barcoding to improve taxonomic resolution

Over the last decade, the abundance of Largemouth Bass Micropterus salmoides has increased in many northern Wisconsin lakes, causing concern among anglers and biologists regarding the potential for Largemouth Bass to negatively affect populations of Walleye Sander vitreus through predation or competition for prey. Our objectives were to determine whether (1) diet overlap and predation occurred between adult Walleyes and Largemouth Bass in four northern Wisconsin lakes and (2) the use of DNA barcoding to reduce unidentifiable fish in diet samples affected conclusions regarding diet overlap. A single occurrence of Walleye predation was observed in the diets of 945 Largemouth Bass. Moderate to high diet overlap was observed between Largemouth Bass and Walleyes throughout much of the study period. The use of DNA barcoding reduced the amount of unidentified fish in diets to <1% and showed that failure to identify fish or fish parts can affect conclusions regarding diet overlap. Largemouth Bass predation is probably not a primary factor affecting Walleye abundance in the lakes we selected, but observed diet overlap suggests the potential for competition between the two species.

Wisconsin↗
USGS2016

Mixed stock analysis of Lake Michigan's Lake Whitefish Coregonus clupeaformis commercial fishery

Lake whitefish ( Coregonus clupeaformis ) support the primary commercial fishery in Lake Michigan. Discrete genetic stocks of lake whitefish have been identified and tagging data suggest stocks are mixed throughout much of the year. Our objectives were to determine if (1) differential stock harvest occurs in the commercial catch, (2) spatial differences in genetic composition of harvested fish were present, and (3) seasonal differences were present in the harvest by commercial fisheries that operate in management zones WI-2 and WFM-01 (Green Bay, Lake Michigan). Mixed stock analysis was conducted on 17 commercial harvest samples (n = 78–145/sample) collected from various ports lake-wide during 2009–2010. Results showed significant mixing with variability in stock composition across most samples. Samples consisted of two to four genetic stocks each accounting for ≥ 10% the catch. In 10 of 17 samples, the stock contributing the largest proportion made up < 60% of the harvest. In general, seasonal and annual differences existed in the proportional stock contribution at a single capture location. Samples from Wisconsin's primary commercial fishing management zone (WI-2) were composed predominately of fish from the Big Bay de Noc (Michigan) stock as opposed to the geographically proximate, North–Moonlight Bay (Wisconsin) stock. These findings have implications for management and allocation of fish to various quotas. Specifically, geographic location of harvest, the current means of allocating harvest quotas, is not the best predictor of genetic stock harvest.

Lake Michigan↗
USGS2014

Relationships among walleye population characteristics and genetic diversity in northern Wisconsin Lakes

The maintenance of genetic integrity is an important goal of fisheries management, yet little is known regarding the effects of management actions (e.g., stocking, harvest regulations) on the genetic diversity of many important fish species. Furthermore, relationships between population characteristics and genetic diversity remain poorly understood. We examined relationships among population demographics (abundance, recruitment, sex ratio, and mean age of the breeding population), stocking intensity, and genetic characteristics (heterozygosity, effective number of alleles, allelic richness, Wright's inbreeding coefficient, effective population size [ N e ], mean d 2 [a measure of inbreeding], mean relatedness, and pairwise population Φ ST estimates) for 15 populations of Walleye Sander vitreus in northern Wisconsin. We also tested for potential demographic and genetic influences on Walleye body condition and early growth. Combinations of demographic variables explained 47.1–79.8% of the variation in genetic diversity. Skewed sex ratios contributed to a reduction in N e and subsequent increases in genetic drift and relatedness among individuals within populations; these factors were correlated to reductions in allelic richness and early growth rate. Levels of inbreeding were negatively related to both age-0 abundance and mean age, suggesting N e was influenced by recruitment and generational overlap. A negative relationship between the effective number of alleles and body condition suggests stocking affected underlying genetic diversity of recipient populations and the overall productivity of the population. These relationships may result from poor performance of stocked fish, outbreeding depression, or density-dependent factors. An isolation-by-distance pattern of genetic diversity was apparent in nonstocked populations, but was disrupted in stocked populations, suggesting that stocking affected genetic structure. Overall, demographic factors were related to genetic diversity and stocking appeared to alter allelic frequencies and the genetic structure of Walleye populations in Wisconsin, possibly resulting in disruption of local adaptation.

Wisconsin↗
USGS2014

Distribution and population genetics of walleye and sauger

Conserving genetic diversity and local adaptations are management priorities for wild populations of exploited species, which increasingly are subject to climate change, habitat loss, and pollution. These constitute growing concerns for the walleye Sander vitreus, an ecologically and economically valuable North American temperate fish with large Laurentian Great Lakes' fisheries. This study compares genetic diversity and divergence patterns across its widespread native range using mitochondrial (mt) DNA control region sequences and nine nuclear DNA microsatellite (μsat) loci, examining historic and contemporary influences. We analyze the genetic and morphological characters of a putative endemic variant– “blue pike” S. v. “glaucus” –described from Lakes Erie and Ontario, which became extinct. Walleye with turquoise-colored mucus also are evaluated, since some have questioned whether these are related to the “blue pike”.

BMC Evolutionary Biology↗
USGS2013

Genetic population structure of muskellunge in the Great Lakes

We quantified genetic relationships among Muskellunge Esox masquinongy from 15 locations in the Great Lakes to determine the extent and distribution of measurable population structure and to identify appropriate spatial scales for fishery management and genetic conservation. We hypothesized that Muskellunge from each area represented genetically distinct populations, which would be evident from analyses of genotype data. A total of 691 Muskellunge were sampled ( n = 10&ndash;127/site) and genetic data were collected at 13 microsatellite loci. Results from a suite of analyses (including pairwise genetic differentiation, Bayesian admixture prediction, analysis of molecular variance, and tests of isolation by distance) indicated the presence of nine distinct genetic groups, including two that were approximately 50 km apart. Geographic proximity and low habitat complexity seemed to facilitate genetic similarity among areas, whereas Muskellunge from areas of greater habitat heterogeneity exhibited high differentiation. Muskellunge from most areas contained private alleles, and mean within-area genetic variation was similar to that reported for other freshwater fishes. Management programs aimed at conserving the broader diversity and long-term sustainability of Muskellunge could benefit by considering the genetically distinct groups as independent fisheries, and individual spawning and nursery habitats could subsequently be protected to conserve the evolutionary potential of Muskellunge.

Great Lakes↗
USGS2013

Evidence of Hybridization between Common Gartersnakes ( Thamnophis sirtalis ) and Butler’s Gartersnakes ( Thamnophis butleri ) in Wisconsin (USA).

Snakes within the genus Thamnophis (Gartersnakes and Ribbonsnakes) are often found in sympatry throughout their geographic distributions. Past work has indicated that some sympatric species within this genus may hybridize, but research of this nature is limited. We attempted to determine whether hybridization occurs between two Thamnophis species native to the upper midwestern United States: Common Gartersnake ( Thamnophis sirtalis ) and the Butler's Gartersnake ( Thamnophis butleri ). We sampled snakes ( n = 411) across 26 locations in Wisconsin, including sites where both species coexist and sites where only Common Gartersnakes are found. We conducted genetic analyses on tissue collected from individuals field-identified as Common Gartersnakes or Butler's Gartersnakes. To verify the results of our field-collected data, we analyzed tissues from juvenile snakes ( n = 4) suspected to be the offspring of a Common Gartersnake and a Butler's Gartersnake that were housed together in a captive situation. Of the field-collected snakes analyzed, eight snakes were consistent with expected Common &times; Butler's Gartersnake hybrids. All four of the captive offspring analyzed resolved as putative hybrids, corresponding with our field-collected samples. Butler's Gartersnake is a globally rare species, endemic only to the upper midwestern United States. Studies involving the potential for hybridization between common and uncommon species are useful from a conservation perspective. The low incidence of hybridization we observed would indicate that hybridization between these species is uncommon. Further research investigating rates of hybridization would help assess any potential threat posed by outbreeding between common and rare gartersnakes in this region of the United States.

Wisconsin↗
USGS2012

Variation in clinical phenotype of human infection among genetic groups of Blastomyces dermatitidis

Background. Blastomyces dermatitidis, the etiologic agent of blastomycosis, has 2 genetic groups and shows varied clinical presentation, ranging from silent infections to fulminant respiratory disease and dissemination. The objective of this study was to determine whether clinical phenotype and outcomes vary based on the infecting organism's genetic group. Methods. We used microsatellites to genotype 227 clinical isolates of B. dermatitidis from Wisconsin patients. For each isolate, corresponding clinical disease characteristics and patient demographic information were abstracted from electronic health records and Wisconsin Division of Health reportable disease forms and questionnaires. Results. In univariate analysis, group 1 isolates were more likely to be associated with pulmonary-only infections ( P < .0001) and constitutional symptoms such as fever ( P < .0001). In contrast, group 2 isolates were more likely to be associated with disseminated disease ( P < .0001), older patient age ( P < .0001), and comorbidities ( P = .0019). In multivariate analysis, disease onset to diagnosis of >1 month ( P < .0001), older age at diagnosis ( P < .0001), and current smoking status ( P = .0001) remained predictors for group 2 infections. Conclusions. This study identified previously unknown associations between clinical phenotype of human infection and genetic groups of B. dermatitidis and provides a framework for further investigations of the genetic basis for virulence in B. dermatitidis .

Journal of Infectious Diseases↗
USGS2012

Genetic and morphological divergence among Cooper's Hawk ( Accipiter cooperii ) populations breeding in north-central and western North America

Cooper's Hawk ( Accipiter cooperii ) populations breeding in the northern portion of the species' range exhibit variation in morphological traits that conforms to predictions based on differences in prey size, tree stand density, and migratory behavior. We examined genetic structure and gene flow and compared divergence at morphological traits ( P ST) and genetic markers ( F ST) to elucidate mechanisms (selection or genetic drift) that promote morphological diversification among Cooper's Hawk populations. Cooper's Hawks appear to conform to the genetic pattern of an east-west divide. Populations in British Columbia are genetically differentiated from north-central populations (Wisconsin, Minnesota, and North Dakota; pairwise microsatellite F ST= 0.031-0.050; mitochondrial DNA &Phi; ST = 0.177-0.204), which suggests that Cooper's Hawks were restricted to at least two Pleistocene glacial refugia. The strength of the Rocky Mountains&mdash;Great Plains area as a barrier to dispersal is further supported by restricted gene-flow rates between British Columbia and other sampled breeding populations. Divergence in morphological traits ( P ST) was also observed across study areas, but with British Columbia and North Dakota differentiated from Wisconsin and Minnesota, a pattern not predicted on the basis of F ST and &Phi; ST interpopulation estimates. Comparison of P STand F STestimates suggests that heterogeneous selection may be acting on Cooper's Hawks in the northern portion of their distribution, which is consistent with hypotheses that variation in prey mass and migratory behavior among populations may be influencing overall body size and wing chord. We were unable to distinguish between the effects of genetic drift and selection on tail length in the study populations.

The Auk↗
USGS2011

Novel microsatellite loci for studies of Thamnophis Gartersnake genetic identity and hybridization

Butler’s Gartersnakes (BGS; Thamnophis butleri ) are confined to open and semi-open canopy wetlands and adjacent uplands, habitats under threat of development in Wisconsin. To address issues of species identity and putative hybridization with congeneric snakes, a suite of 18 microsatellite loci capable of cross-species amplification of Plains Gartersnakes ( T. radix ) and Common Gartersnakes ( T. sirtalis ) was developed. All loci were polymorphic in BGS with mean number of alleles per locus of 16.11 (range = 3–41) and mean observed heterozygosity of 0.659 (range = 0.311–0.978). Loci amplified efficiently in the congeneric species with high levels of intra- and inter-specific variation. These loci will aid ongoing efforts to effectively identify and manage BGS in Wisconsin.

Conservation Genetics Resources↗
USGS2011

Genetic identity of brook trout in Lake Superior south shore streams: Potential for genetic monitoring of stocking and rehabilitation efforts

Rehabilitation of migratory ('coaster') brook trout Salvelinus fontinalis along Lake Superior's south shore is a topic of high interest among resource stakeholders and management agencies. Proposed strategies for rehabilitation of this brook trout life history variant in Wisconsin include supplemental stocking, watershed management, habitat rehabilitation, harvest regulations, or a combination thereof. In an effort to evaluate the success of coaster brook trout rehabilitation efforts, we collected genetic data from four populations of interest (Whittlesey Creek, Bois Brule River, Bark River, and Graveyard Creek) and the hatchery sources used in the Whittlesey Creek supplementation experiment. We characterized the genetic diversity of 30 individuals from each of four populations using 13 microsatellite DNA loci. Levels of genetic variation were consistent with those in similar studies conducted throughout the basin. Significant genetic variation among the populations was observed, enabling adequate population delineation through assignment tests. Overall, 208 of the 211 sampled fish (98.6%) were correctly assigned to their population of origin. Simulated F1 hybrids between two hatchery strains and the Whittlesey Creek population were identifiable in the majority of attempts (90.5-100% accuracy with 0-2.5% error). The genetic markers and analytical techniques described provide the ability to monitor the concurrent coaster brook trout rehabilitation efforts along Wisconsin's Lake Superior south shore, including the detection of hybridization between hatchery and native populations. ?? Copyright by the American Fisheries Society 2008.

Transactions of the American Fisheries Society↗
USGS2011

Population genetic structure of clinical and environmental isolates of Blastomyces dermatitidis based on 27 polymorphic microsatellite markers

Blastomyces dermatitidis , a thermally dimorphic fungus, is the etiologic agent of North American blastomycosis. Clinical presentation is varied, ranging from silent infections to fulminant respiratory disease and dissemination to skin and other sites. Exploration of the population genetic structure of B. dermatitidis would improve our knowledge regarding variation in virulence phenotypes, geographic distribution, and difference in host specificity. The objective of this study was to develop and test a panel of microsatellite markers to delineate the population genetic structure within a group of clinical and environmental isolates of B. dermatitidis . We developed 27 microsatellite markers and genotyped B. dermatitidis isolates from various hosts and environmental sources ( n =112). Assembly of a neighbor-joining tree of allele-sharing distance revealed two genetically distinct groups, separated by a deep node. Bayesian admixture analysis showed that two populations were statistically supported. Principal coordinate analysis also reinforced support for two genetic groups, with the primary axis explaining 61.41% of the genetic variability. Group 1 isolates average 1.8 alleles/locus, whereas group 2 isolates are highly polymorphic, averaging 8.2 alleles/locus. In this data set, alleles at three loci are unshared between the two groups and appear diagnostic. The mating type of individual isolates was determined by PCR. Both mating type-specific genes, the HMG and &alpha;-box domains, were represented in each of the genetic groups, with slightly more isolates having the HMG allele. One interpretation of this study is that the species currently designated B. dermatitidis includes a cryptic subspecies or perhaps a separate species.

Applied and Environmental Microbiology↗
USGS2011

Genetic identity of Thamnophis sp. using microsatellite genetic markers

Butler’s gartersnake (Thamnophis butleri) was previously listed by the Wisconsin Department of Natural Resources as a state threatened species. Several key questions associated with species identity, integrity, and hybridization with other gartersnake species needed to be addressed to further refi ne the management plan for this species. The objectives of this research were: 1) to determine if genetic markers developed in the initial phase of research could identify discrete genetic groups of Wisconsin gartersnakes, 2) to determine if any or all genetic groups delineated in objective one were consistent with Butler’s gartersnake, plains gartersnake (T. radix), and/or common gartersnake (T. sirtalis), and 3) to determine if any of the genetic data were consistent with hybridization occurring between gartersnakes in Wisconsin. Snakes were sampled from various Midwestern locations with a focus on sites in Wisconsin. All snakes were photo-vouchered, morphological landmarks were taken, and a tail snip was collected for genetic analysis. Genetic data from previously developed microsatellite markers discriminated three genetic groups from a composite 13-locus dataset (N=815) using the Bayesian admixture analysis in STRUCTURE v2.3.3. These units were highly consistent with species-groups based on the membership of a small number of known snakes from areas where the species are not thought to co-occur. Using a threshold q-value (proportional genotype) of ≥80%, 498 Butler’s gartersnakes, 93 plains gartersnakes, and 107 common gartersnakes were identifi ed in Wisconsin samples; putative hybrid snakes of Butler’s gartersnake x plain gartersnake (34), Butler’s gartersnake x common gartersnake (8), and a single ambiguous snake were also identifi ed in Wisconsin samples. Levels of divergence among the species groups from Wisconsin were lower than between species groups from other states consistent with either larger than expected Wisconsin population sizes or signifi cant gene fl ow (introgressive hybridization) having occurred among species. Regardless, levels of divergence and overall integrity of the three groups were such that the presence of three species of gartersnakes in Wisconsin was supported and hybridization, at a minimum between Butler’s gartersnakes and the two other species, was shown to occur.

Wisconsin DNR Research Report↗