Dataset Information

Identification of Genetically Important Individuals of the Rediscovered Floreana Galapagos Giant Tortoise (Chelonoidis elephantopus) Provide Founders for Species Restoration Program.

ABSTRACT: Species are being lost at an unprecedented rate due to human-driven environmental changes. The cases in which species declared extinct can be revived are rare. However, here we report that a remote volcano in the Galápagos Islands hosts many giant tortoises with high ancestry from a species previously declared as extinct: Chelonoidis elephantopus or the Floreana tortoise. Of 150 individuals with distinctive morphology sampled from the volcano, genetic analyses revealed that 65 had C. elephantopus ancestry and thirty-two were translocated from the volcano's slopes to a captive breeding center. A genetically informed captive breeding program now being initiated will, over the next decades, return C. elephantopus tortoises to Floreana Island to serve as engineers of the island's ecosystems. Ironically, it was the haphazard translocations by mariners killing tortoises for food centuries ago that created the unique opportunity to revive this "lost" species today.

SUBMITTER: Miller JM

PROVIDER: S-EPMC5597637 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

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Identification of Genetically Important Individuals of the Rediscovered Floreana Galápagos Giant Tortoise (Chelonoidis elephantopus) Provide Founders for Species Restoration Program.

Miller Joshua M JM Quinzin Maud C MC Poulakakis Nikos N Gibbs James P JP Beheregaray Luciano B LB Garrick Ryan C RC Russello Michael A MA Ciofi Claudio C Edwards Danielle L DL Hunter Elizabeth A EA Tapia Washington W Rueda Danny D Carrión Jorge J Valdivieso Andrés A AA Caccone Adalgisa A

Scientific reports 20170913 1

Species are being lost at an unprecedented rate due to human-driven environmental changes. The cases in which species declared extinct can be revived are rare. However, here we report that a remote volcano in the Galápagos Islands hosts many giant tortoises with high ancestry from a species previously declared as extinct: Chelonoidis elephantopus or the Floreana tortoise. Of 150 individuals with distinctive morphology sampled from the volcano, genetic analyses revealed that 65 had C. elephantopu ...[more]

PMID: 28904401

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Project description:Restoration of extirpated species via captive breeding has typically relied on population viability as the primary criterion for evaluating success. This criterion is inadequate when species reintroduction is undertaken to restore ecological functions and interactions. Herein we report on the demographic and ecological outcomes of a five-decade-long population restoration program for a critically endangered species of "ecosystem engineer": the endemic Española giant Galapagos tortoise (Chelonoidis hoodensis). Our analysis of complementary datasets on tortoise demography and movement, tortoise-plant interactions and Española Island's vegetation history indicated that the repatriated tortoise population is secure from a strictly demographic perspective: about half of tortoises released on the island since 1975 were still alive in 2007, in situ reproduction is now significant, and future extinction risk is low with or without continued repatriation. Declining survival rates, somatic growth rates, and body condition of repatriates suggests, however, that resources for continued population growth are increasingly limited. Soil stable carbon isotope analyses indicated a pronounced shift toward woody plants in the recent history of the island's plant community, likely a legacy of changes in competitive relations between woody and herbaceous plants induced by now-eradicated feral goats and prolonged absence of tortoises. Woody plants are of concern because they block tortoise movement and hinder recruitment of cactus--a critical resource for tortoises. Tortoises restrict themselves to remnant cactus patches and areas of low woody plant density in the center of the island despite an apparent capacity to colonize a far greater range, likely because of a lack of cactus elsewhere on the island. We conclude that ecosystem-level criteria for success of species reintroduction efforts take much longer to achieve than population-level criteria; moreover, reinstatement of endangered species as fully functioning ecosystem engineers may often require large-scale habitat restoration efforts in concert with population restoration.

Project description:The conservation of biodiverse areas around the world has contributed to the protection and recovery of endangered species. This has been the case for 11 species of Galapagos giant tortoises (Chelonoidis spp.) that today are successfully maintained over six islands: Española, Santiago, Pinzon, Isabela, San Cristobal and Santa Cruz. A favourable state of conservation will depend however on future development in the islands. In Santa Cruz Island the development of the agricultural areas has encroached on the migratory routes of the southwestern species C. porteri and may be an emergent conflict for tortoise conservation. We investigated the social and ecological inter-linkages using two methods framed under a participatory rural appraisal (PRA) approach: semi-structured interviews and questionnaires to study farmers' perceptions and attitudinal factors regarding giant tortoises; as well as the associated socio-economic impacts of the conflict. Moreover, we coupled the PRA approach with an ecological assessment of giant tortoises' population density by performing transect counts during the two yearly phases of giant tortoises' migration to the lowlands (January to June) and back to the highlands (July to December). Our results indicate that farmers reporting damage and cultivating crops have higher odds of taking actions (fencing and physical actions) towards giant tortoises; regardless of having (or not) a negative perception towards the species. The economic losses for crops and fences averaged 2.8 USD/m2 and 13USD/m, respectively, and provide an initial step to further analyse and characterise the direct and indirect damage costs. Finally, we estimated a density of 76 and 185 individuals of giant tortoises per km2 in the rural area for the lowland and highland migratory phases, respectively. Our approach provides grounded scientific social and ecological information to effectively inform and aid managers, policy and decision makers in the selection of adequate social and ecological criteria to implement the best available options in the resolution of this emergent conservation conflict.

Dataset Information

Identification of Genetically Important Individuals of the Rediscovered Floreana Galapagos Giant Tortoise (Chelonoidis elephantopus) Provide Founders for Species Restoration Program.

Publications

Identification of Genetically Important Individuals of the Rediscovered Floreana Galápagos Giant Tortoise (Chelonoidis elephantopus) Provide Founders for Species Restoration Program.

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