2008/09/22 by Nikos Poulakakis, Scott Glaberman, Michael A. Russello +4 · 161 citations
Environmental Science · Biochemistry, Genetics and Molecular Biology · Psychology · #Turtle Biology and Conservation #Genetic diversity and population structure #Primate Behavior and Ecology #Archipelago #Tortoise #Biology #Population #Ecology #Zoology #Endangered species #Evolutionary biology #Demography
paper · open access · doi:10.1073/pnas.0805340105
published in Proceedings of the National Academy of Sciences 105(40), 15464-15469 (National Academy of Sciences)
openalex publication_date 2008/09/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/02
Giant tortoises, a prominent symbol of the Galápagos archipelago, illustrate the influence of geological history and natural selection on the diversification of organisms. Because of heavy human exploitation, 4 of the 15 known species (Geochelone spp.) have disappeared. Charles Darwin himself detailed the intense harvesting of one species, G. elephantopus, which once was endemic to the island of Floreana. This species was believed to have been exterminated within 15 years of Darwin's historic visit to the Galápagos in 1835. The application of modern DNA techniques to museum specimens combined with long-term study of a system creates new opportunities for identifying the living remnants of extinct taxa in the wild. Here, we use mitochondrial DNA and microsatellite data obtained from museum specimens to show that the population on Floreana was evolutionarily distinct from all other Galápagos tortoise populations. It was demonstrated that some living individuals on the nearby island of Isabela are genetically distinct from the rest of the island's inhabitants. Surprisingly, we found that these "non-native" tortoises from Isabela are of recent Floreana ancestry and closely match the genetic data provided by the museum specimens. Thus, we show that the genetic line of G. elephantopus has not been completely extinguished and still exists in an intermixed population on Isabela. With enough individuals to commence a serious captive breeding program, this finding may help reestablish a species that was thought to have gone extinct more than a century ago and illustrates the power of long-term genetic analysis and the critical role of museum specimens in conservation biology.