Genetic Variation and Its Management Applications in Eastern U.S. Feral Horses

Goodloe, Robin B.; Warren, Robert J.; Cothran, E. Gus; Bratton, Susan Power; Trembicki, Kathryn A.

doi:10.2307/3808969

Cited by 12 publications

(12 citation statements)

References 5 publications

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“…Goodloe et al (1991) found that diversity levels at allozyme loci in horses from Assateague Island were comparable to those found in larger mainland populations. Their study, however, sampled only the CNWR herd on the Virginia end of the island, which has been managed independently and separated from the ASIS herd by a fence.…”

Section: Discussionmentioning

confidence: 70%

Pedigrees and the Study of the Wild Horse Population of Assateague Island National Seashore

et al. 2010

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Recently, a number of papers have addressed the use of pedigrees in the study of wild populations, highlighting the value of pedigrees in conservation management. We used pedigrees to study the horses (Equus caballus) of Assateague Island National Seashore, Maryland, USA, one of a small number of free-ranging animal populations that have been the subject of long-term studies. This population grew from 28 in 1968 to 175 in 2001, causing negative impacts on the island ecosystem. To minimize these effects, an immunocontraception program was instituted, and horse numbers are slowly decreasing. However, there is concern that this program may negatively affect the genetic health of the herd. We found that although mitochondrial DNA diversity is low, nuclear diversity is comparable to that of established breeds. Using genetic data, we verified and amended maternal pedigrees that had been primarily based on behavioral data and inferred paternity using genetic data along with National Park Service records of the historic ranges of males. The resulting pedigrees enabled us to examine demography, founder contributions, rates of inbreeding and loss of diversity over recent generations, as well as the level of kinship among horses. We then evaluated the strategy of removing individuals (using nonlethal means) with the highest mean kinship values. Although the removal strategy increased the retained diversity of founders and decreased average kinship between individuals, it disproportionately impacted sizes of the youngest age classes. Our results suggest that a combined strategy of controlled breeding and immunocontraception would be more effective than removing individuals with high mean kinships in preserving the long-term health and viability of the herd.

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Section: Discussionmentioning

confidence: 70%

Pedigrees and the Study of the Wild Horse Population of Assateague Island National Seashore

et al. 2010

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“…It is expected that the Shackleford Banks, Ocracoke and Corolla herds have some genetic affinity to each other due to their geographic proximity. One study was carried out on the Ocracoke and Shackleford populations, but the sample size for the Shackleford Banks ( n = 4) was small (Goodloe et al. 1991).…”

Section: Introductionmentioning

confidence: 99%

A microsatellite analysis of five Colonial Spanish horse populations of the southeastern United States

2011

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The domestic horse (Equus caballus) was re-introduced to the Americas by Spanish explorers. Although horses from other parts of Europe were subsequently introduced, some New World populations maintain characteristics ascribed to their Spanish heritage. The southeastern United States has a history of Spanish invasion and settlement, and this influence on local feral horse populations includes two feral-recaptured breeds: the Florida Cracker and the Marsh Tacky, both of which are classified as Colonial Spanish horses. The feral Banker horses found on islands off the coast of North Carolina, which include, among others, the Shackleford Banks, the Corolla and the Ocracoke, are also Colonial Spanish horses. Herein we analyse 15 microsatellite loci from 532 feral and 2583 domestic horses in order to compare the genetic variation of these five Colonial Spanish Horse populations to 40 modern horse breeds. We find that the Corolla horse has very low heterozygosity and that both the Corolla and Ocracoke populations have a low mean number of alleles. We also find that the Florida Cracker population has a heterozygosity deficit. In addition, we find evidence of similarity of the Shackleford Banks, Marsh Tacky and Florida Cracker populations to New World Iberian horse breeds, while the origins of the other two populations are less clear.

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“…Calculations suggested that 78 animals were required to maintain an effective population size of 50 where no more than 1% of the genetic diversity is lost per generation (Soulé, 1980). The population composition required was similar to the composition present at the end of 1999 (nine herd stallions, fifteen bachelor males, 22 females of breeding age and 25 immature animals) and to a model for an unmanaged island population of feral horses (Goodloe et al. , 1991).…”

Section: Discussion and Recommendationsmentioning

confidence: 87%

“…If either mortality rates of immature animals have increased or reproductive rates have decreased since 1999, a larger minimum population would be required to maintain an effective population of 50. Estimates of effective population size must, therefore, be used cautiously and must be revised with changes in population parameters (Goodloe et al. , 1991).…”

Section: Discussion and Recommendationsmentioning

confidence: 99%

Monitoring and management of the endangered Cape mountain zebra Equus zebra zebra in the Western Cape, South Africa

Smith

Marais²,

Chadwick³

et al. 2007

African Journal of Ecology

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De Hoop Nature Reserve and a neighbouring conservancy contain the most genetically diverse subpopulation of the Endangered (IUCN) Cape mountain zebra (Equus zebra zebra Linnaeus 1758). Although vital for the long‐term stability of the meta‐population, the population had received limited monitoring post‐1999. We summarize data obtained during a population monitoring programme established in 2005. Ninety‐nine individuals were identified indicating a decline in annual population growth from 6.6% (1995–1999) to 4.5% (1999–2005). The population was male biased and the deficit of females is likely to have prevented additional breeding herd formation resulting in excess nonbreeding males. These animals are currently of limited reproductive value to the meta‐population and may be contributing to the decline in reproductive potential at De Hoop by competing for limited resources. One solution may be to translocate ‘excess’ males to reinforce existing small populations or establish new populations with females from elsewhere provided that a minimum of 78 animals is maintained at De Hoop to limit genetic loss. Population monitoring and effective management strategies for the De Hoop population and the meta‐population are vital to ensure the long‐term survival of Cape mountain zebra and for the success of other species recovery programmes.

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Genetic Variation and Its Management Applications in Eastern U.S. Feral Horses

Cited by 12 publications

References 5 publications

Pedigrees and the Study of the Wild Horse Population of Assateague Island National Seashore

Pedigrees and the Study of the Wild Horse Population of Assateague Island National Seashore

A microsatellite analysis of five Colonial Spanish horse populations of the southeastern United States

Monitoring and management of the endangered Cape mountain zebra Equus zebra zebra in the Western Cape, South Africa

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