title: Small Ne of the Isolated and Unmanaged Horse Population on Sable Island.
abstract: For small, isolated populations 2 common conservation concerns relate to genetic threats: inbreeding and negative consequences associated with loss of genetic diversity due to drift. Mitigating these threats often involves conservation actions that can be controversial, such as translocations or captive breeding programs. Although such actions have been successful in some situations, in others they have had undesirable outcomes. Here, we estimated the effective population size (N e ) of the Sable Island horses to assess the risk to this population of these genetic threats. We found surprising consistency of N e estimates across the 5 different methods used, with a mean of 48 effective individuals. This estimate falls below the 50 criterion of the "50/500 rule," below which inbreeding depression is a concern for population viability. However, simulations and knowledge of population history indicate that this population is still in its early stages of approaching equilibrium between mutation, drift, and genetic diversity; and no negative consequences have been identified that could be associated with inbreeding depression. Therefore, we do not recommend taking management action (such as translocations) at this stage. Rather, we propose continued monitoring of genetic diversity and fitness over time so that trends and any substantial changes can be detected. This represents one of the few unmanaged horse populations in the world, and therefore these data will not only alert us to serious concerns regarding their conservation status, but will also provide a wealth of information about how natural processes drive patterns of reproduction, mortality, and population growth over time.
authors.affiliation: From the Department of Biology, Saint Mary's University, 923 Robie Street, Halifax, Nova Scotia B3H 3C3, Canada (Uzans, McLeod, and Frasier); PO Box 64, Halifax CRO, Halifax, Nova Scotia B3J 2L4, Canada (Lucas); and Nova Scotia Museum of Natural History, Halifax, Nova Scotia B3H 3A6, Canada (Lucas and McLeod).
authors.forename: Andrea J
authors.initials: AJ
authors.lastname: Uzans
authors.affiliation: From the Department of Biology, Saint Mary's University, 923 Robie Street, Halifax, Nova Scotia B3H 3C3, Canada (Uzans, McLeod, and Frasier); PO Box 64, Halifax CRO, Halifax, Nova Scotia B3J 2L4, Canada (Lucas); and Nova Scotia Museum of Natural History, Halifax, Nova Scotia B3H 3A6, Canada (Lucas and McLeod).
authors.forename: Zoe
authors.initials: Z
authors.lastname: Lucas
authors.affiliation: From the Department of Biology, Saint Mary's University, 923 Robie Street, Halifax, Nova Scotia B3H 3C3, Canada (Uzans, McLeod, and Frasier); PO Box 64, Halifax CRO, Halifax, Nova Scotia B3J 2L4, Canada (Lucas); and Nova Scotia Museum of Natural History, Halifax, Nova Scotia B3H 3A6, Canada (Lucas and McLeod).
authors.forename: Brenna A
authors.initials: BA
authors.lastname: McLeod
authors.affiliation: From the Department of Biology, Saint Mary's University, 923 Robie Street, Halifax, Nova Scotia B3H 3C3, Canada (Uzans, McLeod, and Frasier); PO Box 64, Halifax CRO, Halifax, Nova Scotia B3J 2L4, Canada (Lucas); and Nova Scotia Museum of Natural History, Halifax, Nova Scotia B3H 3A6, Canada (Lucas and McLeod). timothy.frasier@smu.ca.
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Frasier
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D002170:Canada; D003247:Conservation of Natural Resources; D005787:Gene Frequency; D014644:Genetic Variation; D005828:Genetics, Population; D005838:Genotype; D006736:Horses / Q000235:genetics*; D007178:Inbreeding; D062312:Islands; D015810:Linkage Disequilibrium; D018895:Microsatellite Repeats; D008957:Models, Genetic; D011156:Population Density
keywords: Equus; Sable Island; effective population size; feral; horse; population viability; wildlife management