Genetically informed captive breeding of hybrids of an extinct species of Galapagos tortoise |
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Authors: | Maud C Quinzin Jonathan Sandoval-Castillo Joshua M Miller Luciano B Beheregaray Michael A Russello Elizabeth A Hunter James P Gibbs Washington Tapia Freddy Villalva Adalgisa Caccone |
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Institution: | 1. Department of Ecology and Evolutionary Biology, Yale University, 21 Sachem Street, New Haven, CT, 06520 U.S.A.;2. Molecular Ecology Lab, College of Science and Engineering, Flinders University, Adelaide, SA, 5001 Australia;3. Department of Biology, University of British Columbia, Okanagan Campus, Kelowna, BC, V1V 1V7 Canada;4. Department of Biology, Georgia Southern University, Statesboro, GA, 30460 U.S.A.;5. Department of Environmental and Forest Biology, College of Environmental Science and Forestry, State University of New York, 247 Illick Hall, Syracuse, NY, 13210 U.S.A.;6. Giant Tortoise Restoration Initiative, Galapagos Conservancy, Fairfax, VA, 22030 U.S.A.;7. Galapagos National Park Directorate, Puerto Ayora, Galapagos, Ecuador |
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Abstract: | Hybridization poses a major challenge for species conservation because it threatens both genetic integrity and adaptive potential. Yet, hybridization can occasionally offer unprecedented opportunity for species recovery if the genome of an extinct taxon is present among living hybrids such that selective breeding could recapture it. We explored the design elements for establishing a captive-breeding program for Galapagos tortoises (Chelonoidis spp.) built around individuals with admixed ancestry involving an extinct species. The target individuals were hybrids between the extinct species from Floreana Island, C. niger, and an extant species, C. becki, which were recently found in the endemic range of C. becki, from Wolf Volcano on Isabela Island. We combined genotypic data from 35 tortoises with high ancestry from C. niger with forward-in-time simulations to explore captive breeding strategies that maximized overall genetic diversity and ancestry from C. niger while accommodating resource constraints, species biology, and the urgency to return tortoises to Floreana Island for facilitating ecosystem restoration. Overall genetic diversity was maximized when in the simulation tortoises were organized in relatively small breeding groups. Substantial amounts of the C. niger genome were captured despite limited resources available for selectively breeding tortoises in captivity. Genetic diversity was maximized when captive-bred offspring were released to the wild rather than being used as additional breeders. Our results provide genetic-based and practical guidance on the inclusion of hybrids with genomic representation from extinct taxa into species restoration programs and informs the ongoing debate on the value of hybrids in biodiversity conservation. |
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Keywords: | Chelonoidis niger ex situ population management Floreana Island forward-in-time simulations genetic ancestry genetic relatedness hybrid conservation value museum samples Chlenoidis niger Isla Floreana linaje genético manejo poblacional ex situ muestras de museos relación genética simulación futura valor de conservación de híbridos 迁地种群管理 杂种保护价值 Chelonoidis niger 弗洛里安娜岛 博物馆标本 遗传相关性 遗传血统 前进式模拟 |
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