Shelled out

For evolutionary biologists reptiles and islands provide rich pickings. One of the world’s largest land reptiles, the komodo dragon, is confined to just a couple of small Indonesian islands, and one of the rarest snakes is found on an islet off the Caribbean island of St. Lucia. Even the heavily touristed Mediterranean island of Mallorca boasts its own lizard species on an offshore islet. But for evolutionary intrigue there is little better destination than the Galápagos Islands. Its endemic giant tortoises pose not only evolutionary questions but urgent conservation ones too: on Pinta island, ‘Lonesome George’ is thought to be the last surviving member of the species Geochelone abingdobi. But a new study, reported in this issue of Current Biology (p. R317–R318), suggests that George may still have a few local relatives left. The research team, led by Michael Russello at the University of British Columbia Okanangan, Canada, has looked at mitochondrial (mt) DNA data from George alongside that of tortoises on the neighbouring Isabela Island. The team studied two populations that live on Volcano Wolf on Isabela, one of which shows considerable morphological diversity. Mt DNA studies revealed both populations to show considerable genetic diversity, including some individuals that show more similarity to other species than to those within their own population. The team was also able to include genetic data for the first time from six museum specimens to help in the analysis. And the researchers concluded that George did indeed have relatives within the Isabela populations. “The detection of Pinta ancestry on Volcano Wolf on Isabela Island provides evidence that Lonesome George is not the only living descendant of G. abingdoni. The identification of eight individuals of mixed ancestry among 27 individuals sampled suggests the need to mount an immediate and comprehensive survey,” the authors write. The need is “to search for additional individuals of Pinta ancestry”. The researchers believe these approaches may help more widely in reconstructing evolutionary patterns, but they hope the identification of Pintanative genotypes may now be possible so that George may not remain lonesome for ever.