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Skaien CL, Arcese P. Local adaptation in island populations of Plectritis congesta that differ in historic exposure to ungulate browsers. Ecology 2020; 101:e03054. [PMID: 32239504 DOI: 10.1002/ecy.3054] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 02/07/2020] [Accepted: 02/24/2020] [Indexed: 11/07/2022]
Abstract
Spatial variation in the occurrence of browsing ungulates can drive local adaptation in plant traits but also lead to trade-offs among traits potentially enhancing competitive ability versus resistance or tolerance to browsing. Plectritis congesta populations co-occurring on islands with and without ungulates offer striking examples of population-level variation in traits, such as plant height and fruit morphology, which may also affect fitness. We monitored split-plot common gardens exposed to and protected from browsing ungulates for 5 yr to test for local adaptation (local vs. foreign comparison) in P. congesta by comparing the survival and fecundity of 4,392 sown fruits from six island populations where ungulates were present ("historically exposed") and six where they were absent ("historically naïve"). Our results indicate that local adaptation to browsing in P. congesta favored rosette formation, delayed flowering, reduced height, and the production of wingless fruits, all of which appeared to enhance survival, fecundity, and population growth in plants from populations historically exposed to ungulate browsers, as compared to plants from historically naïve populations. In contrast, plants from historically naïve populations displayed higher relative fitness in the absence of ungulates, increased in height, flowered earlier, and produced fewer but larger, winged fruits, often in large terminal inflorescences. Our results support the hypothesis that variation in the occurrence of ungulate browsers has led to (1) spatial heterogeneity in natural selection and rapid adaptation in P. congesta populations on islands, and (2) context-dependent trade-offs in the fitness value of traits linked to the resistance or tolerance of browsing versus success in competition for light, pollinators, or other resources. Because patterns of selection in plant communities will vary with the introduction or extirpation of top predators or browsers, we suggest historical context, local adaptation, and the capacity for rapid adaptation should be a focal concern of those aiming to maximize or predict population persistence under environmental change in conservation plans.
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Affiliation(s)
- Cora L Skaien
- Department of Forest and Conservation Sciences, Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia, V6T 1Z4, Canada
| | - Peter Arcese
- Department of Forest and Conservation Sciences, Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia, V6T 1Z4, Canada
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Quinzin MC, Sandoval-Castillo J, Miller JM, Beheregaray LB, Russello MA, Hunter EA, Gibbs JP, Tapia W, Villalva F, Caccone A. Genetically informed captive breeding of hybrids of an extinct species of Galapagos tortoise. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2019; 33:1404-1414. [PMID: 30901116 DOI: 10.1111/cobi.13319] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 03/08/2019] [Accepted: 03/18/2019] [Indexed: 06/09/2023]
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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Affiliation(s)
- Maud C Quinzin
- Department of Ecology and Evolutionary Biology, Yale University, 21 Sachem Street, New Haven, CT, 06520, U.S.A
| | - Jonathan Sandoval-Castillo
- Molecular Ecology Lab, College of Science and Engineering, Flinders University, Adelaide, SA, 5001, Australia
| | - Joshua M Miller
- Department of Ecology and Evolutionary Biology, Yale University, 21 Sachem Street, New Haven, CT, 06520, U.S.A
| | - Luciano B Beheregaray
- Molecular Ecology Lab, College of Science and Engineering, Flinders University, Adelaide, SA, 5001, Australia
| | - Michael A Russello
- Department of Biology, University of British Columbia, Okanagan Campus, Kelowna, BC, V1V 1V7, Canada
| | - Elizabeth A Hunter
- Department of Biology, Georgia Southern University, Statesboro, GA, 30460, U.S.A
| | - James P Gibbs
- 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
| | - Washington Tapia
- Giant Tortoise Restoration Initiative, Galapagos Conservancy, Fairfax, VA, 22030, U.S.A
| | - Freddy Villalva
- Galapagos National Park Directorate, Puerto Ayora, Galapagos, Ecuador
| | - Adalgisa Caccone
- Department of Ecology and Evolutionary Biology, Yale University, 21 Sachem Street, New Haven, CT, 06520, U.S.A
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