Gary S Casper | University of Wisconsin Milwaukee (original) (raw)
Papers by Gary S Casper
Biological Journal of The Linnean Society, Sep 30, 2021
Phylogeographic studies can uncover robust details about the population structure, demographics, ... more Phylogeographic studies can uncover robust details about the population structure, demographics, and diversity of species. The smooth greensnake, Opheodrys vernalis, is a small, cryptic snake occupying mesic grassland and sparsely wooded habitats. Although O. vernalis has a wide geographical range, many metapopulations are patchy and some are declining. We used mitochondrial DNA and double digest restriction-site associated DNA sequencing to construct the first phylogeographic assessment of O. vernalis. Genomic analysis of 119 individuals (mitochondrial DNA) and a subset of another 45 smooth greensnakes (nuclear DNA; N = 3031 single nucleotide polymorphisms) strongly supports two longitudinally separated lineages, with admixture in the Great Lakes region. Post-Pleistocene secondary contact best explains admixture from populations advancing northwards. Overall, populations expressed low heterozygosity, variable inbreeding rates, and moderate to high differentiation. Disjunct populations in the Rocky Mountains and central Great Plains regions might be contracting relicts, whereas northerly populations in more continuous mesic habitats (e.g., Prairie Pothole region, southern Canada) had signals of population expansion. Broadly, conservation management efforts should be focused on local populations, because habitat connectivity may facilitate gene flow and genetic diversity.
Status and Conservation of Midwestern Amphibians
The Editorial Staff of Herpetological Conservation & Biology would like to acknowledge the follow... more The Editorial Staff of Herpetological Conservation & Biology would like to acknowledge the following 360 peer reviewers for their expert opinions in 2014-2015. Your efforts, dedication, and professionalism have ensured that Herpetological Conservation & Biology continues to be a success.
Since their designation in the 1980s, Areas of Concern (AOCs) around the Great Lakes have been th... more Since their designation in the 1980s, Areas of Concern (AOCs) around the Great Lakes have been the focus of multiState and international cleanup efforts that were needed after decades of human activity resulted in severely contaminated sediment, water-quality degradation, loss of habitat for aquatic organisms, and impaired public use. Although individual Great Lake States had been working to cleanup and mitigate environmental concerns, there was insufficient funding and little coordination between Federal and State efforts to address the large and complex set of problems. The Great Lakes Ecosystem Protection Act was passed in 2010, providing for comprehensive multi-State planning and dedicating Federal funds to accelerate cleanup and improve conditions at the AOCs with a particular focus on 14 beneficial use impairments, such as degradation of benthos and degradation of phytoplankton and zooplankton populations. Of Wisconsin’s five AOCs, four lie adjacent to Lake Michigan: Lower Men...
Distinguishing between hybrid zones formed by secondary contact versus parapatric divergence-with... more Distinguishing between hybrid zones formed by secondary contact versus parapatric divergence-with-gene-flow is an important challenge for understanding the interplay of geographic isolation and local adaptation in the origin of species. Similarly, distinguishing between natural hybrid zones and those that formed as a consequence of recent human activities has important conservation implications. Recent work has demonstrated the existence of a narrow hybrid zone between the plains gartersnake (Thamnophis radix) and Butler’s gartersnake (T. butleri) in the Great Lakes region of North America, raising questions about the history and conservation value of genetically admixed populations. Both taxa are of conservation concern, and it is not clear whether to regard hybridization as a threat or a natural interaction. Here we use phylogeographic and population genetic methods to assess the timescales of divergence and hybridization, and test for evidence that the hybrid zone is of recent origin. We assayed AFLP markers and ND2 mitochondrial DNA (mtDNA) sequences from T. radix, T. butleri, and the closely related short-headed gartersnake (T. brachystoma) throughout their North American ranges. We find shallow mtDNA divergence overall and high levels of variation within the contact zone. These patterns are inconsistent with recent contact of long-diverged taxa. It is not possible to distinguish true divergence-with-gene-flow from a long-term secondary contact zone, but we infer that the hybrid zone is a long-standing, natural interaction
All in-text references underlined in blue are linked to publications on ResearchGate, letting you... more All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
Journal of …, 2002
The amphibians and reptiles of the Great Lakes are diverse in their basic biology and natural his... more The amphibians and reptiles of the Great Lakes are diverse in their basic biology and natural history. These species are also widely distributed and overlap highly in their spatial extent. The Great Lakes basin includes 35,000 islands that differ in aspects of their geography, ...
Molecular Phylogenetics and Evolution, 2007
Pleistocene events played an important role in the differentiation of North American vertebrate p... more Pleistocene events played an important role in the differentiation of North American vertebrate populations. Michigan, in particular, and the Great Lakes region, in general, were greatly influenced by the last glaciation. While several hypotheses regarding the recolonization of this region have been advanced, none have been strongly supported. We generated 148 complete ND2 mitochondrial DNA (mtDNA) sequences from common gartersnake (Thamnophis sirtalis) populations throughout the Great Lakes region to evaluate phylogeographic patterns and population structure and to determine whether the distribution of haplotypic variants is related to the post-Pleistocene retreat of the Wisconsinan glacier. The common gartersnake was utilized, as it is believed to have been one of the primary vertebrate invaders of the Great Lakes region following the most recent period of glacial retreat and because it has been a model species for a variety of evolutionary, ecological, behavioral, and physiologic...
Distinguishing between hybrid zones formed by secondary contact versus parapatric divergence-with... more Distinguishing between hybrid zones formed by secondary contact versus parapatric divergence-withgene-flow is an important challenge for understanding the interplay of geographic isolation and local adaptation in the origin of species. Similarly, distinguishing between natural hybrid zones and those that formed as a consequence of recent human activities has important conservation implications. Recent work has demonstrated the existence of a narrow hybrid zone between the plains gartersnake (Thamnophis radix) and Butler's gartersnake (T. butleri) in the Great Lakes region of North America, raising questions about the history and conservation value of genetically admixed populations. Both taxa are of conservation concern, and it is not clear whether to regard hybridization as a threat or a natural interaction. Here we use phylogeographic and population genetic methods to assess the timescales of divergence and hybridization, and test for evidence that the hybrid zone is of recent origin. We assayed AFLP markers and ND2 mitochondrial DNA (mtDNA) sequences from T. radix, T. butleri, and the closely related short-headed gartersnake (T. brachystoma) throughout their North American ranges. We find shallow mtDNA divergence overall and high levels of variation within the contact zone. These patterns are inconsistent with recent contact of long-diverged taxa. It is not possible to distinguish true divergence-with-gene-flow from a longterm secondary contact zone, but we infer that the hybrid zone is a long-standing, natural interaction.
Herpetological Conservation and Biology, 2010
Artificial cover objects (ACOs) can be useful for surveying an area for snake abundance. However... more Artificial cover objects (ACOs) can be useful for surveying an area for snake abundance. However, very little is known about the correlation between environmental conditions, time of day, and ACO capture success rates. We studied the effects of time of day, temperature, humidity, wind speed, and sky cover variables in relation to ACO sampling capture rates of two colubrid species, Thamnophis butleri and Thamnophis sirtalis. We found that time of day, temperature, and sky cover best explained capture with a quadratic function of temperature being a significant variable. An optimal temperature of 26°C with increasing cloudiness was found to produce the highest ACO sampling capture rate. These observations provide some of the first quantitative information regarding temporal and environmental correlates of ACO methodology, and may help improve the efficiency of the ACO technique for surveying snake abundance.
The Journal of the Iowa Academy of Science: JIAS, 2000
s from the conference are available online at www.mpm.edu/collect/vertzo/herp/Daptf/MWabst.html. ... more s from the conference are available online at www.mpm.edu/collect/vertzo/herp/Daptf/MWabst.html. Papers presented at the conference, but not included here, were: Effects of methoprene and UV light on survival and development of Rana pipiens (G.T. Ankley, J.E. Tietge, D.L. Defoe, K.M. Jensen, G.W. Holcombe, E.J. Durhan, S.A. Diamond, and P.K. Schoff); Field and laboratory evidence for the role of retinoids in producing frog malformities (B. Blumberg, D.M. Gardiner, D. Hoppe and R.M. Evans); Iowa's declining amphibians (J.L. Christiansen and C. Van Gorp); Examination of a long-term monitoring technique and the effects of fire management on the herpetofauna of Chilton Creek Preserve, Shannon and Carter counties, Missouri (B.M. Churchwell and K.S. Mierzwa); Deformed frogs: developmental and molecular mechanisms (D.M. Gardiner and D. Hoppe); Wisconsin's amphibian malformations: 1960-1997 (H. Gilbertson, R. DuBois and R. Hay); The North American Amphibian Monitoring Program (J. Gr...
1School of Natural Sciences, Black Hills State University, 1200 University Street, Spearfish, SD ... more 1School of Natural Sciences, Black Hills State University, 1200 University Street, Spearfish, SD 577999008, USA 2Department of Biology, University of Texas at Tyler, 3900 University Boulevard, Tyler, TX 75799, USA 3University of Wisconsin-Milwaukee Field Station, 3095 Blue Goose Road, Saukville, WI 53080, USA 4Department of Zoology, Denver Museum of Nature & Science, 2001 Colorado Boulevard, Denver, CO 80205, USA
Biological Journal of The Linnean Society, Sep 30, 2021
Phylogeographic studies can uncover robust details about the population structure, demographics, ... more Phylogeographic studies can uncover robust details about the population structure, demographics, and diversity of species. The smooth greensnake, Opheodrys vernalis, is a small, cryptic snake occupying mesic grassland and sparsely wooded habitats. Although O. vernalis has a wide geographical range, many metapopulations are patchy and some are declining. We used mitochondrial DNA and double digest restriction-site associated DNA sequencing to construct the first phylogeographic assessment of O. vernalis. Genomic analysis of 119 individuals (mitochondrial DNA) and a subset of another 45 smooth greensnakes (nuclear DNA; N = 3031 single nucleotide polymorphisms) strongly supports two longitudinally separated lineages, with admixture in the Great Lakes region. Post-Pleistocene secondary contact best explains admixture from populations advancing northwards. Overall, populations expressed low heterozygosity, variable inbreeding rates, and moderate to high differentiation. Disjunct populations in the Rocky Mountains and central Great Plains regions might be contracting relicts, whereas northerly populations in more continuous mesic habitats (e.g., Prairie Pothole region, southern Canada) had signals of population expansion. Broadly, conservation management efforts should be focused on local populations, because habitat connectivity may facilitate gene flow and genetic diversity.
Status and Conservation of Midwestern Amphibians
The Editorial Staff of Herpetological Conservation & Biology would like to acknowledge the follow... more The Editorial Staff of Herpetological Conservation & Biology would like to acknowledge the following 360 peer reviewers for their expert opinions in 2014-2015. Your efforts, dedication, and professionalism have ensured that Herpetological Conservation & Biology continues to be a success.
Since their designation in the 1980s, Areas of Concern (AOCs) around the Great Lakes have been th... more Since their designation in the 1980s, Areas of Concern (AOCs) around the Great Lakes have been the focus of multiState and international cleanup efforts that were needed after decades of human activity resulted in severely contaminated sediment, water-quality degradation, loss of habitat for aquatic organisms, and impaired public use. Although individual Great Lake States had been working to cleanup and mitigate environmental concerns, there was insufficient funding and little coordination between Federal and State efforts to address the large and complex set of problems. The Great Lakes Ecosystem Protection Act was passed in 2010, providing for comprehensive multi-State planning and dedicating Federal funds to accelerate cleanup and improve conditions at the AOCs with a particular focus on 14 beneficial use impairments, such as degradation of benthos and degradation of phytoplankton and zooplankton populations. Of Wisconsin’s five AOCs, four lie adjacent to Lake Michigan: Lower Men...
Distinguishing between hybrid zones formed by secondary contact versus parapatric divergence-with... more Distinguishing between hybrid zones formed by secondary contact versus parapatric divergence-with-gene-flow is an important challenge for understanding the interplay of geographic isolation and local adaptation in the origin of species. Similarly, distinguishing between natural hybrid zones and those that formed as a consequence of recent human activities has important conservation implications. Recent work has demonstrated the existence of a narrow hybrid zone between the plains gartersnake (Thamnophis radix) and Butler’s gartersnake (T. butleri) in the Great Lakes region of North America, raising questions about the history and conservation value of genetically admixed populations. Both taxa are of conservation concern, and it is not clear whether to regard hybridization as a threat or a natural interaction. Here we use phylogeographic and population genetic methods to assess the timescales of divergence and hybridization, and test for evidence that the hybrid zone is of recent origin. We assayed AFLP markers and ND2 mitochondrial DNA (mtDNA) sequences from T. radix, T. butleri, and the closely related short-headed gartersnake (T. brachystoma) throughout their North American ranges. We find shallow mtDNA divergence overall and high levels of variation within the contact zone. These patterns are inconsistent with recent contact of long-diverged taxa. It is not possible to distinguish true divergence-with-gene-flow from a long-term secondary contact zone, but we infer that the hybrid zone is a long-standing, natural interaction
All in-text references underlined in blue are linked to publications on ResearchGate, letting you... more All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
Journal of …, 2002
The amphibians and reptiles of the Great Lakes are diverse in their basic biology and natural his... more The amphibians and reptiles of the Great Lakes are diverse in their basic biology and natural history. These species are also widely distributed and overlap highly in their spatial extent. The Great Lakes basin includes 35,000 islands that differ in aspects of their geography, ...
Molecular Phylogenetics and Evolution, 2007
Pleistocene events played an important role in the differentiation of North American vertebrate p... more Pleistocene events played an important role in the differentiation of North American vertebrate populations. Michigan, in particular, and the Great Lakes region, in general, were greatly influenced by the last glaciation. While several hypotheses regarding the recolonization of this region have been advanced, none have been strongly supported. We generated 148 complete ND2 mitochondrial DNA (mtDNA) sequences from common gartersnake (Thamnophis sirtalis) populations throughout the Great Lakes region to evaluate phylogeographic patterns and population structure and to determine whether the distribution of haplotypic variants is related to the post-Pleistocene retreat of the Wisconsinan glacier. The common gartersnake was utilized, as it is believed to have been one of the primary vertebrate invaders of the Great Lakes region following the most recent period of glacial retreat and because it has been a model species for a variety of evolutionary, ecological, behavioral, and physiologic...
Distinguishing between hybrid zones formed by secondary contact versus parapatric divergence-with... more Distinguishing between hybrid zones formed by secondary contact versus parapatric divergence-withgene-flow is an important challenge for understanding the interplay of geographic isolation and local adaptation in the origin of species. Similarly, distinguishing between natural hybrid zones and those that formed as a consequence of recent human activities has important conservation implications. Recent work has demonstrated the existence of a narrow hybrid zone between the plains gartersnake (Thamnophis radix) and Butler's gartersnake (T. butleri) in the Great Lakes region of North America, raising questions about the history and conservation value of genetically admixed populations. Both taxa are of conservation concern, and it is not clear whether to regard hybridization as a threat or a natural interaction. Here we use phylogeographic and population genetic methods to assess the timescales of divergence and hybridization, and test for evidence that the hybrid zone is of recent origin. We assayed AFLP markers and ND2 mitochondrial DNA (mtDNA) sequences from T. radix, T. butleri, and the closely related short-headed gartersnake (T. brachystoma) throughout their North American ranges. We find shallow mtDNA divergence overall and high levels of variation within the contact zone. These patterns are inconsistent with recent contact of long-diverged taxa. It is not possible to distinguish true divergence-with-gene-flow from a longterm secondary contact zone, but we infer that the hybrid zone is a long-standing, natural interaction.
Herpetological Conservation and Biology, 2010
Artificial cover objects (ACOs) can be useful for surveying an area for snake abundance. However... more Artificial cover objects (ACOs) can be useful for surveying an area for snake abundance. However, very little is known about the correlation between environmental conditions, time of day, and ACO capture success rates. We studied the effects of time of day, temperature, humidity, wind speed, and sky cover variables in relation to ACO sampling capture rates of two colubrid species, Thamnophis butleri and Thamnophis sirtalis. We found that time of day, temperature, and sky cover best explained capture with a quadratic function of temperature being a significant variable. An optimal temperature of 26°C with increasing cloudiness was found to produce the highest ACO sampling capture rate. These observations provide some of the first quantitative information regarding temporal and environmental correlates of ACO methodology, and may help improve the efficiency of the ACO technique for surveying snake abundance.
The Journal of the Iowa Academy of Science: JIAS, 2000
s from the conference are available online at www.mpm.edu/collect/vertzo/herp/Daptf/MWabst.html. ... more s from the conference are available online at www.mpm.edu/collect/vertzo/herp/Daptf/MWabst.html. Papers presented at the conference, but not included here, were: Effects of methoprene and UV light on survival and development of Rana pipiens (G.T. Ankley, J.E. Tietge, D.L. Defoe, K.M. Jensen, G.W. Holcombe, E.J. Durhan, S.A. Diamond, and P.K. Schoff); Field and laboratory evidence for the role of retinoids in producing frog malformities (B. Blumberg, D.M. Gardiner, D. Hoppe and R.M. Evans); Iowa's declining amphibians (J.L. Christiansen and C. Van Gorp); Examination of a long-term monitoring technique and the effects of fire management on the herpetofauna of Chilton Creek Preserve, Shannon and Carter counties, Missouri (B.M. Churchwell and K.S. Mierzwa); Deformed frogs: developmental and molecular mechanisms (D.M. Gardiner and D. Hoppe); Wisconsin's amphibian malformations: 1960-1997 (H. Gilbertson, R. DuBois and R. Hay); The North American Amphibian Monitoring Program (J. Gr...
1School of Natural Sciences, Black Hills State University, 1200 University Street, Spearfish, SD ... more 1School of Natural Sciences, Black Hills State University, 1200 University Street, Spearfish, SD 577999008, USA 2Department of Biology, University of Texas at Tyler, 3900 University Boulevard, Tyler, TX 75799, USA 3University of Wisconsin-Milwaukee Field Station, 3095 Blue Goose Road, Saukville, WI 53080, USA 4Department of Zoology, Denver Museum of Nature & Science, 2001 Colorado Boulevard, Denver, CO 80205, USA