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Fisk EA, Cassirer EF, Huggler KS, Pessier AP, White LA, Ramsay JD, Goldsmith EW, Drankhan HR, Wolking RM, Manlove KR, Nordeen T, Hogg JT, Taylor KR. ABORTION AND NEONATAL MORTALITY DUE TO TOXOPLASMA GONDII IN BIGHORN SHEEP (OVIS CANADENSIS). J Wildl Dis 2023; 59:37-48. [PMID: 36648765 DOI: 10.7589/jwd-d-22-00057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Accepted: 09/08/2022] [Indexed: 01/18/2023]
Abstract
Low lamb recruitment can be an obstacle to bighorn sheep (Ovis canadensis) conservation and restoration. Causes of abortion and neonate loss in bighorn sheep, which may affect recruitment, are poorly understood. Toxoplasma gondii is a major cause of abortion and stillbirth in domestic small ruminants worldwide, but no reports exist documenting abortion or neonatal death in bighorn sheep attributable to toxoplasmosis. Between March 2019 and May 2021, eight fetal and neonatal bighorn lamb cadavers from four western US states (Idaho, Montana, Nebraska, and Washington) were submitted to the Washington Animal Disease Diagnostic Laboratory for postmortem examination, histologic examination, and ancillary testing to determine the cause of abortion or neonatal death. Necrotizing encephalitis characteristic of toxoplasmosis was identified histologically in six of eight cases, and T. gondii infection was confirmed by PCR in five cases with characteristic lesions. Other lesions attributable to toxoplasmosis were pneumonia (3/5 cases) and myocarditis (2/5 cases). Protozoal cysts were identified histologically within brain, lung, heart, skeletal muscle, adipose tissue, or a combination of samples in all five sheep with PCR-confirmed T. gondii infections. Seroprevalence of T. gondii ranged from 40-81% of adult females sampled in the Washington population in October and November 2018-2021, confirming high rates of exposure before detection of Toxoplasma abortions in this study. Of 1,149 bighorn sheep postmortem samples submitted to Washington Animal Disease Diagnostic Laboratory between January 2000 and May 2021, 21 of which were from fetuses or neonates, a single case of chronic toxoplasmosis was diagnosed in one adult ewe. Recent identification of Toxoplasma abortions in bighorn sheep suggests that toxoplasmosis is an underappreciated cause of reproductive loss. Abortions and neonatal mortalities should be investigated through postmortem and histologic examination, particularly in herds that are chronically small, demographically stagnant, or exhibit reproductive rates lower than expected.
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Affiliation(s)
- Elis A Fisk
- Washington Animal Disease Diagnostic Laboratory, 1940 SE Olympia Ave., Pullman, Washington 99164-7034, USA
- Department of Veterinary Microbiology and Pathology, Washington State University College of Veterinary Medicine, PO Box 647040, Pullman, Washington 99164-7040, USA
| | - E Frances Cassirer
- Idaho Department of Fish and Game, 3316 16th St., Lewiston, Idaho 83501, USA
| | - Katey S Huggler
- Department of Fish and Wildlife Sciences, University of Idaho, 875 Perimeter Dr., Moscow, Idaho 83844, USA
| | - Allan P Pessier
- Washington Animal Disease Diagnostic Laboratory, 1940 SE Olympia Ave., Pullman, Washington 99164-7034, USA
- Department of Veterinary Microbiology and Pathology, Washington State University College of Veterinary Medicine, PO Box 647040, Pullman, Washington 99164-7040, USA
| | - Laura A White
- Washington Animal Disease Diagnostic Laboratory, 1940 SE Olympia Ave., Pullman, Washington 99164-7034, USA
- Department of Veterinary Microbiology and Pathology, Washington State University College of Veterinary Medicine, PO Box 647040, Pullman, Washington 99164-7040, USA
| | - Joshua D Ramsay
- Washington Animal Disease Diagnostic Laboratory, 1940 SE Olympia Ave., Pullman, Washington 99164-7034, USA
- Department of Veterinary Microbiology and Pathology, Washington State University College of Veterinary Medicine, PO Box 647040, Pullman, Washington 99164-7040, USA
| | - Elizabeth W Goldsmith
- Washington Animal Disease Diagnostic Laboratory, 1940 SE Olympia Ave., Pullman, Washington 99164-7034, USA
- Department of Veterinary Microbiology and Pathology, Washington State University College of Veterinary Medicine, PO Box 647040, Pullman, Washington 99164-7040, USA
| | - Holly R Drankhan
- Washington Animal Disease Diagnostic Laboratory, 1940 SE Olympia Ave., Pullman, Washington 99164-7034, USA
- Department of Veterinary Microbiology and Pathology, Washington State University College of Veterinary Medicine, PO Box 647040, Pullman, Washington 99164-7040, USA
| | - Rebecca M Wolking
- Washington Animal Disease Diagnostic Laboratory, 1940 SE Olympia Ave., Pullman, Washington 99164-7034, USA
- Department of Veterinary Microbiology and Pathology, Washington State University College of Veterinary Medicine, PO Box 647040, Pullman, Washington 99164-7040, USA
| | - Kezia R Manlove
- Department of Wildland Resources and Ecology Center, Utah State University, 5230 Old Main Hill, NR 206, Logan, Utah 84322, USA
| | - Todd Nordeen
- Nebraska Game and Parks Commission, 2200 N 33rd St., PO Box 30370, Lincoln, Nebraska 68503, USA
| | - John T Hogg
- Montana Conservation Science Institute Ltd., 5200 Miller Creek Rd., Missoula, Montana 59803, USA
| | - Kyle R Taylor
- Washington Animal Disease Diagnostic Laboratory, 1940 SE Olympia Ave., Pullman, Washington 99164-7034, USA
- Department of Veterinary Microbiology and Pathology, Washington State University College of Veterinary Medicine, PO Box 647040, Pullman, Washington 99164-7040, USA
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Martin AM, Hogg JT, Manlove KR, LaSharr TN, Shannon JM, McWhirter DE, Miyasaki H, Monteith KL, Cross PC. Disease and secondary sexual traits: effects of pneumonia on horn size of bighorn sheep. J Wildl Manage 2022. [DOI: 10.1002/jwmg.22154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Alynn M. Martin
- U.S. Geological Survey Northern Rocky Mountain Science Center 2327 University Way, Suite #2 Bozeman MT 59715 USA
| | - John T. Hogg
- Montana Conservation Science Institute Missoula MT 59803 USA
| | - Kezia R. Manlove
- Department of Wildland Resources and Ecology Center Utah State University Logan UT 84322 USA
| | - Tayler N. LaSharr
- Haub School of Environment and Natural Resources, Wyoming Cooperative Fish and Wildlife Research Unit, Department of Zoology and Physiology University of Wyoming Laramie WY 82071 USA
| | - Justin M. Shannon
- Utah Division of Wildlife Resources Utah Department of Natural Resources Salt Lake City UT 84116 USA
| | | | | | - Kevin L. Monteith
- Haub School of Environment and Natural Resources, Wyoming Cooperative Fish and Wildlife Research Unit, Department of Zoology and Physiology University of Wyoming Laramie WY 82071 USA
| | - Paul C. Cross
- U.S. Geological Survey Northern Rocky Mountain Science Center 2327 University Way, Suite #2 Bozeman MT 59715 USA
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Besser TE, Cassirer EF, Lisk A, Nelson D, Manlove KR, Cross PC, Hogg JT. Natural history of a bighorn sheep pneumonia epizootic: Source of infection, course of disease, and pathogen clearance. Ecol Evol 2021; 11:14366-14382. [PMID: 34765112 PMCID: PMC8571585 DOI: 10.1002/ece3.8166] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 08/21/2021] [Accepted: 08/31/2021] [Indexed: 11/06/2022] Open
Abstract
A respiratory disease epizootic at the National Bison Range (NBR) in Montana in 2016-2017 caused an 85% decline in the bighorn sheep population, documented by observations of its unmarked but individually identifiable members, the subjects of an ongoing long-term study. The index case was likely one of a small group of young bighorn sheep on a short-term exploratory foray in early summer of 2016. Disease subsequently spread through the population, with peak mortality in September and October and continuing signs of respiratory disease and sporadic mortality of all age classes through early July 2017. Body condition scores and clinical signs suggested that the disease affected ewe groups before rams, although by the end of the epizootic, ram mortality (90% of 71) exceeded ewe mortality (79% of 84). Microbiological sampling 10 years to 3 months prior to the epizootic had documented no evidence of infection or exposure to Mycoplasma ovipneumoniae at NBR, but during the epizootic, a single genetic strain of M. ovipneumoniae was detected in affected animals. Retrospective screening of domestic sheep flocks near the NBR identified the same genetic strain in one flock, presumptively the source of the epizootic infection. Evidence of fatal lamb pneumonia was observed during the first two lambing seasons following the epizootic but was absent during the third season following the death of the last identified M. ovipneumoniae carrier ewe. Monitoring of life-history traits prior to the epizootic provided no evidence that environmentally and/or demographically induced nutritional or other stress contributed to the epizootic. Furthermore, the epizootic occurred despite proactive management actions undertaken to reduce risk of disease and increase resilience in this population. This closely observed bighorn sheep epizootic uniquely illustrates the natural history of the disease including the (presumptive) source of spillover, course, severity, and eventual pathogen clearance.
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Affiliation(s)
- Thomas E. Besser
- Department of Veterinary Microbiology and PathologyWashington State UniversityPullmanWashingtonUSA
| | | | - Amy Lisk
- US Fish and Wildlife ServiceMoieseMontanaUSA
| | - Danielle Nelson
- Washington Animal Disease Diagnostic LaboratoryDepartment of Veterinary Microbiology and PathologyWashington State UniversityPullmanWashingtonUSA
| | - Kezia R. Manlove
- Department of Wildland Resources & Ecology CenterUtah State UniversityLoganUtahUSA
| | - Paul C. Cross
- U. S. Geological SurveyNorthern Rocky Mountain Science CenterBozemanMontanaUSA
| | - John T. Hogg
- Montana Conservation Science InstituteMissoulaMontanaUSA
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Affiliation(s)
- Susanne Schindler
- University of Zurich; Department of Evolutionary Biology and Environmental Studies; Winterthurer Str. 190 8057 Zurich Switzerland
| | - Marco Festa-Bianchet
- Université de Sherbrooke; Departement de biologie; 2500 boulevard de l'Université Sherbrooke QC J1K 2R1 Canada
| | - John T. Hogg
- Montana Conservation Science Institute; 5200 Upper Miller Creek Road Missoula MT 59803 USA
| | - Fanie Pelletier
- Université de Sherbrooke; Departement de biologie; 2500 boulevard de l'Université Sherbrooke QC J1K 2R1 Canada
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Hogg JT, Dunn SJ, Poissant J, Pelletier F, Byers JA. Capital vs. income‐dependent optimal birth date in two North American ungulates. Ecosphere 2017. [DOI: 10.1002/ecs2.1766] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- John T. Hogg
- Montana Conservation Science Institute 5200 Upper Miller Creek Road Missoula Montana 59803 USA
| | - Stacey J. Dunn
- Department of Biological Sciences University of Idaho Moscow Idaho 83844 USA
| | - Jocelyn Poissant
- Department of Biological Sciences University of Alberta Edmonton Alberta T6G 2E9 Canada
- Centre for Ecology and Conservation University of Exeter Penryn Cornwall TR10 9FE UK
| | - Fanie Pelletier
- Faculté des Sciences Université de Sherbrooke Sherbrooke Québec J1K 2R1 Canada
| | - John A. Byers
- Department of Biological Sciences University of Idaho Moscow Idaho 83844 USA
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Kardos M, Luikart G, Bunch R, Dewey S, Edwards W, McWilliam S, Stephenson J, Allendorf FW, Hogg JT, Kijas J. Whole‐genome resequencing uncovers molecular signatures of natural and sexual selection in wild bighorn sheep. Mol Ecol 2015; 24:5616-32. [DOI: 10.1111/mec.13415] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Revised: 09/23/2015] [Accepted: 09/28/2015] [Indexed: 12/12/2022]
Affiliation(s)
- Marty Kardos
- Division of Biological Sciences University of Montana Missoula MT 59812 USA
- Evolutionary Biology Centre Uppsala University SE‐75236 Uppsala Sweden
| | - Gordon Luikart
- Division of Biological Sciences University of Montana Missoula MT 59812 USA
- Division of Biological Sciences Flathead Lake Biological Station Fish and Wildlife Genomics Group University of Montana Polson MT 59860 USA
| | - Rowan Bunch
- CSIRO Agriculture 306 Carmody Road St Lucia Brisbane Qld 4067 Australia
| | - Sarah Dewey
- Grand Teton National Park Moose WY 83012 USA
| | - William Edwards
- Wyoming Game and Fish Department Wildlife Disease Laboratory Laramie WY 82070 USA
| | - Sean McWilliam
- CSIRO Agriculture 306 Carmody Road St Lucia Brisbane Qld 4067 Australia
| | | | - Fred W. Allendorf
- Division of Biological Sciences University of Montana Missoula MT 59812 USA
| | - John T. Hogg
- Montana Conservation Science Institute Missoula MT 59803 USA
| | - James Kijas
- CSIRO Agriculture 306 Carmody Road St Lucia Brisbane Qld 4067 Australia
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Abstract
Linkage disequilibrium (LD) is the nonrandom association of alleles at two markers. Patterns of LD have biological implications as well as practical ones when designing association studies or conservation programs aimed at identifying the genetic basis of fitness differences within and among populations. However, the temporal dynamics of LD in wild populations has received little empirical attention. In this study, we examined the overall extent of LD, the effect of sample size on the accuracy and precision of LD estimates, and the temporal dynamics of LD in two populations of bighorn sheep (Ovis canadensis) with different demographic histories. Using over 200 microsatellite loci, we assessed two metrics of multi-allelic LD, D', and χ ('2). We found that both populations exhibited high levels of LD, although the extent was much shorter in a native population than one that was founded via translocation, experienced a prolonged bottleneck post founding, followed by recent admixture. In addition, we observed significant variation in LD in relation to the sample size used, with small sample sizes leading to depressed estimates of the extent of LD but inflated estimates of background levels of LD. In contrast, there was not much variation in LD among yearly cross-sections within either population once sample size was accounted for. Lack of pronounced interannual variability suggests that researchers may not have to worry about interannual variation when estimating LD in a population and can instead focus on obtaining the largest sample size possible.
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Affiliation(s)
- Joshua M Miller
- Department of Biological Sciences, University of Alberta Edmonton, Alberta, Canada
| | - Jocelyn Poissant
- Centre for Ecology and Conservation, University of Exeter Penryn Campus, UK
| | - René M Malenfant
- Department of Biological Sciences, University of Alberta Edmonton, Alberta, Canada
| | - John T Hogg
- Montana Conservation Science Institute 5200 Upper Miller Creek Road, Missoula, Montana, USA
| | - David W Coltman
- Department of Biological Sciences, University of Alberta Edmonton, Alberta, Canada
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8
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Abstract
This article documents the public availability of approximately 15 000 polymorphic SNP loci for the bighorn sheep Ovis canadensis.
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Affiliation(s)
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- Molecular Ecology Resources Editorial Office, 6270 University Blvd, Vancouver, BC, V6T 1Z4, Canada.
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9
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Abstract
Genetic rescue is a management intervention whereby a small population is supplemented with individuals from other populations in an attempt to reverse the effects of inbreeding and increased genetic load. One such rescue was recently documented in the population of bighorn sheep (Ovis canadensis) within the National Bison Range wildlife refuge (Montana, USA). Here, we examine the locus-specific effects of rescue in this population using a newly developed genome-wide set of 195 microsatellite loci and first-generation linkage map. We found that the rate of introgression varied among loci and that 111 loci, 57% of those examined, deviated from patterns of neutral inheritance. The most common deviation was an excess of homozygous genotypes relative to neutral expectations, indicative of directional selection. As in previous study of this rescue, individuals with more introduced alleles had higher reproductive success and longevity. In addition, we found 30 loci, distributed throughout the genome, which seem to have individual effects on these life history traits. Although the potential for outbreeding depression is a major concern when translocating individuals between populations, we found no evidence of such effects in this population.
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Affiliation(s)
- J M Miller
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9.
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Poissant J, Davis CS, Malenfant RM, Hogg JT, Coltman DW. QTL mapping for sexually dimorphic fitness-related traits in wild bighorn sheep. Heredity (Edinb) 2011; 108:256-63. [PMID: 21847139 DOI: 10.1038/hdy.2011.69] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Dissecting the genetic architecture of fitness-related traits in wild populations is key to understanding evolution and the mechanisms maintaining adaptive genetic variation. We took advantage of a recently developed genetic linkage map and phenotypic information from wild pedigreed individuals from Ram Mountain, Alberta, Canada, to study the genetic architecture of ecologically important traits (horn volume, length, base circumference and body mass) in bighorn sheep. In addition to estimating sex-specific and cross-sex quantitative genetic parameters, we tested for the presence of quantitative trait loci (QTLs), colocalization of QTLs between bighorn sheep and domestic sheep, and sex × QTL interactions. All traits showed significant additive genetic variance and genetic correlations tended to be positive. Linkage analysis based on 241 microsatellite loci typed in 310 pedigreed animals resulted in no significant and five suggestive QTLs (four for horn dimension on chromosomes 1, 18 and 23, and one for body mass on chromosome 26) using genome-wide significance thresholds (Logarithm of odds (LOD) >3.31 and >1.88, respectively). We also confirmed the presence of a horn dimension QTL in bighorn sheep at the only position known to contain a similar QTL in domestic sheep (on chromosome 10 near the horns locus; nominal P<0.01) and highlighted a number of regions potentially containing weight-related QTLs in both species. As expected for sexually dimorphic traits involved in male-male combat, loci with sex-specific effects were detected. This study lays the foundation for future work on adaptive genetic variation and the evolutionary dynamics of sexually dimorphic traits in bighorn sheep.
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Affiliation(s)
- J Poissant
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
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11
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Poissant J, Hogg JT, Davis CS, Miller JM, Maddox JF, Coltman DW. Genetic linkage map of a wild genome: genomic structure, recombination and sexual dimorphism in bighorn sheep. BMC Genomics 2010; 11:524. [PMID: 20920197 PMCID: PMC3091677 DOI: 10.1186/1471-2164-11-524] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Accepted: 09/28/2010] [Indexed: 12/23/2022] Open
Abstract
Background The construction of genetic linkage maps in free-living populations is a promising tool for the study of evolution. However, such maps are rare because it is difficult to develop both wild pedigrees and corresponding sets of molecular markers that are sufficiently large. We took advantage of two long-term field studies of pedigreed individuals and genomic resources originally developed for domestic sheep (Ovis aries) to construct a linkage map for bighorn sheep, Ovis canadensis. We then assessed variability in genomic structure and recombination rates between bighorn sheep populations and sheep species. Results Bighorn sheep population-specific maps differed slightly in contiguity but were otherwise very similar in terms of genomic structure and recombination rates. The joint analysis of the two pedigrees resulted in a highly contiguous map composed of 247 microsatellite markers distributed along all 26 autosomes and the X chromosome. The map is estimated to cover about 84% of the bighorn sheep genome and contains 240 unique positions spanning a sex-averaged distance of 3051 cM with an average inter-marker distance of 14.3 cM. Marker synteny, order, sex-averaged interval lengths and sex-averaged total map lengths were all very similar between sheep species. However, in contrast to domestic sheep, but consistent with the usual pattern for a placental mammal, recombination rates in bighorn sheep were significantly greater in females than in males (~12% difference), resulting in an autosomal female map of 3166 cM and an autosomal male map of 2831 cM. Despite differing genome-wide patterns of heterochiasmy between the sheep species, sexual dimorphism in recombination rates was correlated between orthologous intervals. Conclusions We have developed a first-generation bighorn sheep linkage map that will facilitate future studies of the genetic architecture of trait variation in this species. While domestication has been hypothesized to be responsible for the elevated mean recombination rate observed in domestic sheep, our results suggest that it is a characteristic of Ovis species. However, domestication may have played a role in altering patterns of heterochiasmy. Finally, we found that interval-specific patterns of sexual dimorphism were preserved among closely related Ovis species, possibly due to the conserved position of these intervals relative to the centromeres and telomeres. This study exemplifies how transferring genomic resources from domesticated species to close wild relative can benefit evolutionary ecologists while providing insights into the evolution of genomic structure and recombination rates of domesticated species.
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Affiliation(s)
- Jocelyn Poissant
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
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Poissant J, Shafer ABA, Davis CS, Mainguy J, Hogg JT, Côté SD, Coltman DW. Genome-wide cross-amplification of domestic sheep microsatellites in bighorn sheep and mountain goats. Mol Ecol Resour 2009; 9:1121-6. [PMID: 21564850 DOI: 10.1111/j.1755-0998.2009.02575.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We tested for cross-species amplification of microsatellite loci located throughout the domestic sheep (Ovis aries) genome in two north American mountain ungulates (bighorn sheep, Ovis canadensis, and mountain goats, Oreamnos americanus). We identified 247 new polymorphic markers in bighorn sheep (≥ 3 alleles in one of two study populations) and 149 in mountain goats (≥ 2 alleles in a single study population) using 648 and 576 primer pairs, respectively. Our efforts increased the number of available polymorphic microsatellite markers to 327 for bighorn sheep and 180 for mountain goats. The average distance between successive polymorphic bighorn sheep and mountain goat markers inferred from the Australian domestic sheep genome linkage map (mean ± 1 SD) was 11.9 ± 9.2 and 15.8 ± 13.8 centimorgans, respectively. The development of genomic resources in these wildlife species enables future studies of the genetic architecture of trait variation.
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Affiliation(s)
- J Poissant
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E9.
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Poissant J, Wilson AJ, Festa-Bianchet M, Hogg JT, Coltman DW. Quantitative genetics and sex-specific selection on sexually dimorphic traits in bighorn sheep. Proc Biol Sci 2008; 275:623-8. [PMID: 18211870 DOI: 10.1098/rspb.2007.1361] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Sexual conflict at loci influencing traits shared between the sexes occurs when sex-specific selection pressures are antagonistic relative to the genetic correlation between the sexes. To assess whether there is sexual conflict over shared traits, we estimated heritability and intersexual genetic correlations for highly sexually dimorphic traits (horn volume and body mass) in a wild population of bighorn sheep (Ovis canadensis) and quantified sex-specific selection using estimates of longevity and lifetime reproductive success. Body mass and horn volume showed significant additive genetic variance in both sexes, and intersexual genetic correlations were 0.24+/-0.28 for horn volume and 0.63+/-0.30 for body mass. For horn volume, selection coefficients did not significantly differ from zero in either sex. For body weight, selection coefficients were positive in females but did not differ from zero in males. The absence of detectable sexually antagonistic selection suggests that currently there are no sexual conflicts at loci influencing horn volume and body mass.
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Affiliation(s)
- Jocelyn Poissant
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9
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15
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Abstract
Natural populations worldwide are increasingly fragmented by habitat loss. Isolation at small population size is thought to reduce individual and population fitness via inbreeding depression. However, little is known about the time-scale over which adverse genetic effects may develop in natural populations or the number and types of traits likely to be affected. The benefits of restoring gene flow to isolates are therefore also largely unknown. In contrast, the potential costs of migration (e.g. disease spread) are readily apparent. Management for ecological connectivity has therefore been controversial and sometimes avoided. Using pedigree and life-history data collected during 25 years of study, we evaluated genetic decline and rescue in a population of bighorn sheep founded by 12 individuals in 1922 and isolated at an average size of 42 animals for 10-12 generations. Immigration was restored experimentally, beginning in 1985. We detected marked improvements in reproduction, survival and five fitness-related traits among descendants of the 15 recent migrants. Trait values were increased by 23-257% in maximally outbred individuals. This is the first demonstration, to our knowledge, of increased male and female fitness attributable to outbreeding realized in a fully competitive natural setting. Our findings suggest that genetic principles deserve broader recognition as practical management tools with near-term consequences for large-mammal conservation.
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Affiliation(s)
- John T Hogg
- Montana Conservation Science Institute 5200 Upper Miller Creek Road, Missoula, MT 59803, USA.
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16
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Festa-Bianchet M, Coulson T, Gaillard JM, Hogg JT, Pelletier F. Stochastic predation events and population persistence in bighorn sheep. Proc Biol Sci 2006; 273:1537-43. [PMID: 16777749 PMCID: PMC1560313 DOI: 10.1098/rspb.2006.3467] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2005] [Accepted: 12/28/2005] [Indexed: 11/12/2022] Open
Abstract
Many studies have reported temporal changes in the relative importance of density-dependence and environmental stochasticity in affecting population growth rates, but they typically assume that the predominant factor limiting growth remains constant over long periods of time. Stochastic switches in limiting factors that persist for multiple time-steps have received little attention, but most wild populations may periodically experience such switches. Here, we consider the dynamics of three populations of individually marked bighorn sheep (Ovis canadensis) monitored for 24-28 years. Each population experienced one or two distinct cougar (Puma concolor) predation events leading to population declines. The onset and duration of predation events were stochastic and consistent with predation by specialist individuals. A realistic Markov chain model confirms that predation by specialist cougars can cause extinction of isolated populations. We suggest that such processes may be common. In such cases, predator-prey equilibria may only occur at large geographical and temporal scales, and are unlikely with increasing habitat fragmentation.
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Affiliation(s)
- Marco Festa-Bianchet
- Université de Sherbrooke Département de biologie Sherbrooke, Québec J1K 2R1, Canada.
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17
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de la Fuente J, Atkinson MW, Hogg JT, Miller DS, Naranjo V, Almazán C, Anderson N, Kocan KM. Genetic Characterization of Anaplasma ovis Strains from Bighorn Sheep in Montana. J Wildl Dis 2006; 42:381-5. [PMID: 16870861 DOI: 10.7589/0090-3558-42.2.381] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Wildlife reservoir species and genetic diversity of Anaplasma ovis (Rickettsiales: Anaplasmataceae) have been poorly characterized. Bighorn sheep (Ovis canadensis), captured in Montana from December 2004 to January 2005, were tested for antibodies to Anaplasma spp.; the presence of A. ovis was determined by the characterization of major surface protein msp4 sequences. Anaplasma antibodies were detected in 25/180 (14%) sampled bighorn sheep and A. ovis msp4 sequences were amplified by polymerase chain reaction (PCR) and sequenced from 9/23 (39%) of seropositive animals. All animals were negative by PCR for the related pathogens, Anaplasma phagocytophilum and Anaplasma marginale. All msp4 sequences identified in the bighorn sheep were identical and corresponded to a single A. ovis genotype that was identical to a sheep isolate reported previously from Idaho. The finding of a single genotype of A. ovis in this wild herd of bighorn sheep was in contrast to the genetic diversity reported for A. marginale in cattle herds in the western United States and worldwide. These results demonstrated that bighorn sheep may be a wildlife reservoir of A. ovis in Montana.
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Affiliation(s)
- José de la Fuente
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, Oklahoma 74078, USA.
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Coltman DW, O'Donoghue P, Hogg JT, Festa-Bianchet M. Selection and genetic (co)variance in bighorn sheep. Evolution 2005; 59:1372-82. [PMID: 16050112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Genetic theory predicts that directional selection should deplete additive genetic variance for traits closely related to fitness, and may favor the maintenance of alleles with antagonistically pleiotropic effects on fitness-related traits. Trait heritability is therefore expected to decline with the degree of association with fitness, and some genetic correlations between selected traits are expected to be negative. Here we demonstrate a negative relationship between trait heritability and association with lifetime reproductive success in a wild population of bighorn sheep (Ovis canadensis) at Ram Mountain, Alberta, Canada. Lower heritability for fitness-related traits, however, was not wholly a consequence of declining genetic variance, because those traits showed high levels of residual variance. Genetic correlations estimated between pairs of traits with significant heritability were positive. Principal component analyses suggest that positive relationships between morphometric traits constitute the main axis of genetic variation. Trade-offs in the form of negative genetic or phenotypic correlations among the traits we have measured do not appear to constrain the potential for evolution in this population.
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Affiliation(s)
- David W Coltman
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada.
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Coltman DW, O'Donoghue P, Jorgenson JT, Hogg JT, Strobeck C, Festa-Bianchet M. Undesirable evolutionary consequences of trophy hunting. Nature 2004; 426:655-8. [PMID: 14668862 DOI: 10.1038/nature02177] [Citation(s) in RCA: 443] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2003] [Accepted: 10/17/2003] [Indexed: 11/09/2022]
Abstract
Phenotype-based selective harvests, including trophy hunting, can have important implications for sustainable wildlife management if they target heritable traits. Here we show that in an evolutionary response to sport hunting of bighorn trophy rams (Ovis canadensis) body weight and horn size have declined significantly over time. We used quantitative genetic analyses, based on a partly genetically reconstructed pedigree from a 30-year study of a wild population in which trophy hunting targeted rams with rapidly growing horns, to explore the evolutionary response to hunter selection on ram weight and horn size. Both traits were highly heritable, and trophy-harvested rams were of significantly higher genetic 'breeding value' for weight and horn size than rams that were not harvested. Rams of high breeding value were also shot at an early age, and thus did not achieve high reproductive success. Declines in mean breeding values for weight and horn size therefore occurred in response to unrestricted trophy hunting, resulting in the production of smaller-horned, lighter rams, and fewer trophies.
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Affiliation(s)
- David W Coltman
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
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Coltman DW, O'Donoghue P, Jorgenson JT, Hogg JT, Strobeck C, Festa-Bianchet M. Undesirable evolutionary consequences of trophy hunting. Nature 2003; 426:655-658. [PMID: 14668862 DOI: 10.1038/nature02187.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2003] [Accepted: 10/17/2003] [Indexed: 05/22/2023]
Abstract
Phenotype-based selective harvests, including trophy hunting, can have important implications for sustainable wildlife management if they target heritable traits. Here we show that in an evolutionary response to sport hunting of bighorn trophy rams (Ovis canadensis) body weight and horn size have declined significantly over time. We used quantitative genetic analyses, based on a partly genetically reconstructed pedigree from a 30-year study of a wild population in which trophy hunting targeted rams with rapidly growing horns, to explore the evolutionary response to hunter selection on ram weight and horn size. Both traits were highly heritable, and trophy-harvested rams were of significantly higher genetic 'breeding value' for weight and horn size than rams that were not harvested. Rams of high breeding value were also shot at an early age, and thus did not achieve high reproductive success. Declines in mean breeding values for weight and horn size therefore occurred in response to unrestricted trophy hunting, resulting in the production of smaller-horned, lighter rams, and fewer trophies.
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Affiliation(s)
- David W Coltman
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
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Forbes SH, Hogg JT. Assessing population structure at high levels of differentiation: microsatellite comparisons of bighorn sheep and large carnivores. Anim Conserv 1999. [DOI: 10.1111/j.1469-1795.1999.tb00068.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Abstract
We compared genotypes at eight (AC)n microsatellite loci in domestic sheep (Ovis aries) and wild Rocky Mountain bighorn sheep (O. canadensis). The domestic sheep had greater genetic variation, higher allele-size variances, and larger allele sizes than the wild sheep. Accumulating evidence from higher taxonomic comparisons shows that these parameters are biased if microsatellite loci are selected in one taxon and used in another. Our results demonstrate similar biases between congeneric species. We compared standard measures of genetic variation, differentiation, and distance within and between species (H, D, FST) to newer measures based on allele-size variance (SW, SB, RST). The size-based distances better detected species-level divergence, but standard measures better distinguished allopatric populations. Empirical calibration of these measures at the subspecies level is needed to establish their useful ranges.
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Affiliation(s)
- S H Forbes
- Division of Biological Sciences, University of Montana, Missoula 59812, USA
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Byers JA, Hogg JT. Environmental effects on prenatal growth rate in pronghorn and bighorn: further evidence for energy constraint on sex-biased maternal expenditure. Behav Ecol 1995. [DOI: 10.1093/beheco/6.4.451] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Abstract
Rocky Mountain bighorn rams obtained copulations by defending single estrous ewes (tending), fighting tending rams for temporary access to defended ewes (coursing), or moving and holding ewes away from other rams beyond the periphery of a traditional tending area (blocking). Coursing and blocking illustrate a feature of many male alternative mating strategies: the ability of males regularly to create mating opportunities.
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