Data from: Genetic rediscovery of an ‘extinct’ Galápagos giant tortoise species

Genes from recently extinct species can live on in the genomes of extant individuals of mixed ancestry. Recently, Poulakakis et al. detected genetic signatures of the giant Galápagos tortoise once endemic to Floreana Island (Chelonoidis elephantopus) within eleven hybrid individuals of otherwise pure C. becki on Volcano Wolf, Isabela Island. Movement of tortoises among islands by pirate and whaling ships was not uncommon during the 1800’s, representing a likely mechanism by which individuals from Floreana were translocated to northern Isabela, despite being presumed extinct soon after Charles Darwin’s historic voyage to the Galápagos Islands in 1835. These eleven hybrid individuals with C. elephantopus ancestry were thought to be the last genetic vestiges of a unique evolutionary lineage in the wild. Here we report that reproductively mature purebred tortoises of the recently ‘extinct’ C. elephantopus from Floreana Island are very likely still alive today, as identified and tracked through the genetic footprints’ left in the genomes of very recent hybrid offspring on Volcano Wolf, Isabela Island. If found, these purebred C. elephantopus individuals could constitute core founders of a captive breeding program directed towards resurrecting this species.近期已灭绝物种的基因，可留存于携带有混合祖先谱系的现存个体基因组中。近日，Poulakakis等学者在伊莎贝拉岛沃尔夫火山的11只看似为纯C. becki的杂合个体的基因组中，检测到了此前仅分布于弗洛雷亚纳岛的加拉帕戈斯巨龟（Chelonoidis elephantopus）的遗传特征。19世纪期间，海盗与捕鲸船在各岛屿间转运巨龟的现象并不罕见，这极有可能是弗洛雷亚纳岛巨龟被迁移至伊莎贝拉岛北部的途径——尽管在1835年查尔斯·达尔文历史性造访加拉帕戈斯群岛后，该物种很快被认定为野外灭绝。这11只携带有C. elephantopus祖先谱系的杂合个体，曾被认为是该独特演化支系在野外仅存的遗传遗迹。本研究通过伊莎贝拉岛沃尔夫火山近期诞生的杂合后代基因组中留存的遗传印记，追踪并证实：来自弗洛雷亚纳岛、曾被认定“灭绝”的C. elephantopus纯繁成熟个体，如今极有可能仍存活于世。若能找到这些纯繁C. elephantopus个体，它们或将成为该物种人工繁育复活计划的核心奠基种源。