Published online 24 July 2008 | Nature | doi:10.1038/news.2008.981
Updated online: 12 August 2008

News

Does fatherhood loom for Lonesome George?

Female companion of unique Galapagos tortoise lays promising clutch of eggs.

Galapagos scientists are in a state of extreme excitement following the news that the iconic giant tortoise known as Lonesome George could be about to become a father.

tortoiseIs George not so lonesome tonight?Mark Putney /Creative Commons

Back in 1972, park wardens rescued George, the sole surviving giant tortoise of the northerly Galapagos island of Pinta, and took him into captivity at the Charles Darwin Research Station (CDRS) on the central island of Santa Cruz. In 1990, two closely related female tortoises were brought from nearby Isabela Island to join him, and conservationists watched keenly in the hope that some hybrid offspring might result. Yet almost two decades of failed mountings passed without visible success. "We'd more or less given up hope of having success with those females," says Felipe Cruz, director of technical assistance at the CDRS.

But in an unexpected twist to George's otherwise gloomy tale, staff at the Galapagos National Park discovered on 20 July that one of the females had excavated a nest and furnished it with a clutch of nine eggs. The two females have occasionally laid the odd egg in the past, says Cruz, but as far as the scientists know nothing like this has happened before.

The wardens succeeded in recovering three of the eggs intact, and these are now being incubated artificially according to a well-established protocol. The news has come as a surprise to Linda Cayot, former head of protection at the CDRS and now science advisor for the US-based Galapagos Conservancy. But she wants confirmation that the eggs are fertile. "Tortoises can lay infertile eggs without ever having been with a male, much the way chickens do," she says. According to Park sources, this confirmation will not be forthcoming until mid-November.

Increased interest

Although there have been no known sightings of a full-blown copulation between George and either of his companions, he has seemed to be showing more interest in the females during the past few months. "When I was in the Galapagos last November I did see George attempting to mate, but sadly at that stage the female walked away," says Toni Darton, chief executive of the UK-based Galapagos Conservation Trust. Since then, George's mating efforts have occasionally been accompanied by the kind of moaning usually reserved for sex.

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If the eggs do turn out to be fertile, scientists will begin entertaining the possibility of captive breeding the Pinta tortoise back from the brink of extinction. Last year, geneticists analysing blood samples collected from tortoises on Isabela found evidence of hybrid animals with clear signs of Pinta ancestry1. A team of wardens and scientists will travel there in December to begin the hunt for them. These animals could be very valuable in a breeding programme, says Gisella Caccone, a senior research scientist in the Department of Ecology and Evolutionary Biology at Yale University in New Haven, Connecticut.

She and her colleagues are awaiting the imminent arrival of the remaining six eggs from George’s enclosure, which were damaged by the female during laying. If they yield a George-like genetic signature, this would at least confirm that he is producing sperm after all these years of sexual inactivity, says Caccone.

Meanwhile, ambitious plans to introduce Española tortoises to Pinta as ecological stand-ins for Lonesome George and his long-dead ancestors will still go ahead, according to Park authorities. 

Updated:

5 August 2008: Eight more eggs have now been "discovered":http://www.galapagos.org/2008/index.php?id=139 in Lonesome George's enclosure.

  • References

    1. Russello, M. A. et al. Curr. Biol. 17, R317–R318 (2007)
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