{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,21]],"date-time":"2026-10-21T03:46:26Z","timestamp":1792554386610,"version":"4.5.0"},"reference-count":40,"publisher":"National Academy of Sciences","issue":"23","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[1999,11,9]]},"abstract":"<jats:p>\n                    Perhaps the most enduring debate in reptile systematics has involved the giant Gal\u00e1pagos tortoises (\n                    <jats:italic>Geochelone nigra<\/jats:italic>\n                    ), whose origins and systematic relationships captivated Charles Darwin and remain unresolved to this day. Here we report a phylogenetic reconstruction based on mitochondrial DNA sequences from Gal\u00e1pagos tortoises and\n                    <jats:italic>Geochelone<\/jats:italic>\n                    from mainland South America and Africa. The closest living relative to the Gal\u00e1pagos tortoise is not among the larger-bodied tortoises of South America but is the relatively small-bodied\n                    <jats:italic>Geochelone chilensis<\/jats:italic>\n                    , or Chaco tortoise. The split between\n                    <jats:italic>G. chilensis<\/jats:italic>\n                    and the Gal\u00e1pagos lineage probably occurred 6 to 12 million years ago, before the origin of the oldest extant Gal\u00e1pagos island. Our data suggest that the four named southern subspecies on the largest island, Isabela, are not distinct genetic units, whereas a genetically distinct northernmost Isabela subspecies is probably the result of a separate colonization. Most unexpectedly, the lone survivor of the\n                    <jats:italic>abingdoni<\/jats:italic>\n                    subspecies from Pinta Island (\u201cLonesome George\u201d) is very closely related to tortoises from San Crist\u00f3bal and Espa\u00f1ola, the islands farthest from the island of Pinta. To rule out a possible recent transplant of Lonesome George, we sequenced DNA from three tortoises collected on Pinta in 1906. They have sequences identical to Lonesome George, consistent with his being the last survivor of his subspecies. This finding may provide guidance in finding a mate for Lonesome George, who so far has failed to reproduce.\n                  <\/jats:p>","DOI":"10.1073\/pnas.96.23.13223","type":"journal-article","created":{"date-parts":[[2002,7,26]],"date-time":"2002-07-26T10:38:21Z","timestamp":1027679901000},"page":"13223-13228","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":134,"title":["Origin and evolutionary relationships of giant Gal\u00e1pagos tortoises"],"prefix":"10.1073","volume":"96","author":[{"given":"Adalgisa","family":"Caccone","sequence":"first","affiliation":[{"name":"Department of Ecology and Evolutionary Biology and Molecular Systematics and Conservation Genetics Laboratory, Yale Institute for Biospherics Studies, Yale University, New Haven, CT 06520-8106; College of Environmental Science and Forestry, State University of New York, Syracuse, NY 13210; and Dipartimento di Biologia Animale e dell\u2019Uomo, Universit\u00e0 di Roma \u201cLa Sapienza\u201d, 00185 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"James P.","family":"Gibbs","sequence":"additional","affiliation":[{"name":"Department of Ecology and Evolutionary Biology and Molecular Systematics and Conservation Genetics Laboratory, Yale Institute for Biospherics Studies, Yale University, New Haven, CT 06520-8106; College of Environmental Science and Forestry, State University of New York, Syracuse, NY 13210; and Dipartimento di Biologia Animale e dell\u2019Uomo, Universit\u00e0 di Roma \u201cLa Sapienza\u201d, 00185 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Valerio","family":"Ketmaier","sequence":"additional","affiliation":[{"name":"Department of Ecology and Evolutionary Biology and Molecular Systematics and Conservation Genetics Laboratory, Yale Institute for Biospherics Studies, Yale University, New Haven, CT 06520-8106; College of Environmental Science and Forestry, State University of New York, Syracuse, NY 13210; and Dipartimento di Biologia Animale e dell\u2019Uomo, Universit\u00e0 di Roma \u201cLa Sapienza\u201d, 00185 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Elizabeth","family":"Suatoni","sequence":"additional","affiliation":[{"name":"Department of Ecology and Evolutionary Biology and Molecular Systematics and Conservation Genetics Laboratory, Yale Institute for Biospherics Studies, Yale University, New Haven, CT 06520-8106; College of Environmental Science and Forestry, State University of New York, Syracuse, NY 13210; and Dipartimento di Biologia Animale e dell\u2019Uomo, Universit\u00e0 di Roma \u201cLa Sapienza\u201d, 00185 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jeffrey R.","family":"Powell","sequence":"additional","affiliation":[{"name":"Department of Ecology and Evolutionary Biology and Molecular Systematics and Conservation Genetics Laboratory, Yale Institute for Biospherics Studies, Yale University, New Haven, CT 06520-8106; College of Environmental Science and Forestry, State University of New York, Syracuse, NY 13210; and Dipartimento di Biologia Animale e dell\u2019Uomo, Universit\u00e0 di Roma \u201cLa Sapienza\u201d, 00185 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[1999,11,9]]},"reference":[{"key":"e_1_3_4_1_2","volume-title":"Journal of Researches into the Geology and Natural History of the Various Countries Visited by H. 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