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Thompson MA, McCann BE, Rhen T, Simmons R. Population genomics provide insight into ancestral relationships and diversity of the feral horses of Theodore Roosevelt National Park. Ecol Evol 2024; 14:e11197. [PMID: 38571790 PMCID: PMC10985374 DOI: 10.1002/ece3.11197] [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] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 03/04/2024] [Accepted: 03/12/2024] [Indexed: 04/05/2024] Open
Abstract
Theodore Roosevelt National Park (TRNP) manages a herd of feral horses (Equus caballus) which was present on the landscape prior to the establishment of the park. The population presents a unique scenario in that it has experienced fairly intensive and well-documented management since the park's establishment, including herd size reductions, intentional introduction of diversity, and subsequent attempts to remove introduced lineages. This provides an interesting case study on the genetic effects of diverse evolutionary forces on an isolated feral population. To explore the effects of these forces and clarify the relationship of this feral herd with other horses, we used genome-wide markers to examine the population structure of a combined dataset containing common established breeds. Using the Illumina Equine 70k BeadChip, we sampled SNPs across the genome for 118 TRNP horses and evaluated the inbreeding coefficient f and runs of homozygosity (RoH). To identify breed relationships, we compared 23 representative TRNP samples with 792 horses from 35 different breeds using genomic population structure analyses. Mean f of TRNP horses was 0.180, while the mean f for all other breeds in the dataset was 0.116 (SD 0.079). RoH analysis indicates that the TRNP population has experienced recent inbreeding in a timeframe consistent with their management. With Bayesian clustering, PCA, and maximum likelihood phylogeny, TRNP horses show genetic differentiation from other breeds, likely due to isolation, historical population bottlenecks, and genetic drift. However, maximum likelihood phylogeny places them with moderate confidence (76.8%) among draft breeds, which is consistent with the known history of breeds used on early North Dakota ranches and stallions subsequently introduced to the park herd. These findings will help resolve speculation about the origins of the herd and inform management decisions for the TRNP herd.
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Affiliation(s)
- Melissa A. Thompson
- Department of BiologyUniversity of North DakotaGrand ForksNorth DakotaUSA
- Theodore Roosevelt National ParkNational Park ServiceMedoraNorth DakotaUSA
| | - Blake E. McCann
- Theodore Roosevelt National ParkNational Park ServiceMedoraNorth DakotaUSA
| | - Turk Rhen
- Department of BiologyUniversity of North DakotaGrand ForksNorth DakotaUSA
| | - Rebecca Simmons
- Department of BiologyUniversity of North DakotaGrand ForksNorth DakotaUSA
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Thompson MA, McCann BE, Simmons RB, Rhen T. Major locus on ECA18 influences effectiveness of GonaCon vaccine in feral horses. J Reprod Immunol 2023; 155:103779. [PMID: 36462462 DOI: 10.1016/j.jri.2022.103779] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 11/02/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022]
Abstract
Contraceptive vaccines are used to reduce birth rates in wild and feral animal populations. While the immunocontraceptive GonaCon-Equine has proven effective in reducing fertility among female feral horses, there is individual variation in the duration of infertility following treatment. To identify genetic factors influencing the effectiveness of GonaCon-Equine, we conducted a genome-wide association study of 88 mares from a feral population genotyped using the Illumina GGP Equine 70k SNP array. Contraceptive treatment schedules and long-term foaling rates have been recorded for each individual. We used mixed linear models to control for relatedness among mares. We found a significant association (p < 5 ×10-8) with a locus on equine chromosome 18. The most likely candidate genes in this region are STAT1 and STAT4, which are both involved in immune system function. Variation in STAT function could affect the immune response to the vaccine, leading to variation in contraceptive efficacy. Additional SNPs reaching a less stringent threshold of significance (p < 5 ×10-6) were located on other chromosomes near known immune system genes, supporting the hypothesis that variation in immunocontraceptive efficacy can be attributed to genetic variation in immune response rather than fertility genes.
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Affiliation(s)
- Melissa A Thompson
- Department of Biology, University of North Dakota, Grand Forks, ND 58202, USA; Theodore Roosevelt National Park, National Park Service, Medora, ND 58645, USA.
| | - Blake E McCann
- Theodore Roosevelt National Park, National Park Service, Medora, ND 58645, USA
| | - Rebecca B Simmons
- Department of Biology, University of North Dakota, Grand Forks, ND 58202, USA
| | - Turk Rhen
- Department of Biology, University of North Dakota, Grand Forks, ND 58202, USA
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Baker DL, Powers JG, Ransom JI, McCann BE, Oehler MW, Bruemmer JE, Galloway NL, Eckery DC, Nett TM. Reimmunization increases contraceptive effectiveness of gonadotropin-releasing hormone vaccine (GonaCon-Equine) in free-ranging horses (Equus caballus): Limitations and side effects. PLoS One 2018; 13:e0201570. [PMID: 30063758 PMCID: PMC6067756 DOI: 10.1371/journal.pone.0201570] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 07/17/2018] [Indexed: 11/19/2022] Open
Abstract
Wildlife and humans are increasingly competing for resources worldwide, and a diverse, innovative, and effective set of management tools is needed. Controlling abundance of wildlife species that are simultaneously protected, abundant, competitive for resources, and in conflict with some stakeholders but beloved by others, is a daunting challenge. Free-ranging horses (Equus caballus) present such a conundrum and managers struggle for effective tools for regulating their abundance. Controlling reproduction of female horses presents a potential alternative. During 2009–2017, we determined the long-term effectiveness of GnRH vaccine (GonaCon-Equine) both as a single immunization and subsequent reimmunization on reproduction and side effects in free-ranging horses. At a scheduled management roundup in 2009, we randomly assigned 57 adult mares to either a GonaCon-Equine treatment group (n = 29) or a saline control group (n = 28). In a second roundup in 2013, we administered a booster vaccination to these same mares. We used annual ground observations to estimate foaling proportions, social behaviors, body condition, and injection site reactions. We found this vaccine to be safe for pregnant females and neonates, with no overt deleterious behavioral side effects during the breeding season. The proportion of treated mares that foaled following a single vaccination was lower than that for control mares for the second (P = 0.03) and third (P = 0.08) post-treatment foaling seasons but was similar (P = 0.67) to untreated mares for the fourth season, demonstrating reversibility of the primary vaccine treatment. After two vaccinations, however, the proportion of females giving birth was lower (P <0.001) than that for control mares for three consecutive years and ranged from 0.0–0.16. The only detectable adverse side effect of vaccination was intramuscular swelling at the vaccination site. Regardless of vaccine treatment (primary/secondary), approximately 62% (34/55) of immunized mares revealed a visible reaction at the vaccine injection site. However, none of these mares displayed any evidence of lameness, altered gait or abnormal range of movement throughout the 8 years they were observed in this study. Our research suggests that practical application of this vaccine in feral horses will require an initial inoculation that may provide only modest suppression of fertility followed by reimmunization that together could result in greater reduction in population growth rates over time.
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Affiliation(s)
- Dan L. Baker
- Animal Reproduction and Biotechnology Laboratory, Department of Biological Sciences, Colorado State University, Fort Collins, Colorado, United States of America
- * E-mail:
| | - Jenny G. Powers
- Biological Resources Division, National Park Service, Fort Collins, Colorado, United States of America
| | - Jason I. Ransom
- Department of Ecosystem Science and Sustainability, Colorado State University, Fort Collins, Colorado, United States of America
| | - Blake E. McCann
- Theodore Roosevelt National Park, National Park Service, Medora, North Dakota, United States of America
| | - Michael W. Oehler
- Theodore Roosevelt National Park, National Park Service, Medora, North Dakota, United States of America
| | - Jason E. Bruemmer
- Animal Reproduction and Biotechnology Laboratory, Department of Biological Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Nathan L. Galloway
- Biological Resources Division, National Park Service, Fort Collins, Colorado, United States of America
| | - Douglas C. Eckery
- National Wildlife Research Center, Wildlife Services, Animal and Plant Health Inspection Service, United States Department of Agriculture, Fort Collins, Colorado, United States of America
| | - Terry M. Nett
- Animal Reproduction and Biotechnology Laboratory, Department of Biological Sciences, Colorado State University, Fort Collins, Colorado, United States of America
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McCann BE, Smyser TJ, Schmit BS, Newman RA, Piaggio AJ, Malek MJ, Swafford SR, Sweitzer RA, Simmons RB. Molecular population structure for feral swine in the United States. J Wildl Manage 2018. [DOI: 10.1002/jwmg.21452] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [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]
Affiliation(s)
- Blake E. McCann
- Resource Management, Wildlife, Theodore Roosevelt National Park315 2nd Avenue, P.O. Box 7MedoraND 58645USA
| | - Timothy J. Smyser
- U.S. Department of Agriculture, Wildlife Services4101 La Porte AvenueFort CollinsCO 80521USA
| | - Brandon S. Schmit
- U.S. Department of Agriculture, Wildlife Services4101 La Porte AvenueFort CollinsCO 80521USA
| | - Robert A. Newman
- Department of BiologyUniversity of North Dakota10 Cornell Street, Stop 9019Grand ForksND 58202USA
| | - Antoinette J. Piaggio
- U.S. Department of Agriculture, Wildlife Services4101 La Porte AvenueFort CollinsCO 80521USA
| | - Mathew J. Malek
- University of South DakotaSanford School of MedicineDepartment of General Surgery1400 West 22nd StreetSioux FallsSD 57105USA
| | - Seth R. Swafford
- U.S. Fish and Wildlife Service12595 MS Highway 149Yazoo CityMS 39194USA
| | | | - Rebecca B. Simmons
- Department of BiologyUniversity of North Dakota10 Cornell Street, Stop 9019Grand ForksND 58202USA
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