New gecko species identified in West African rainforests

PART OF THE FAMILY: The West African forest gecko, which was thought to be one species, is actually at least four, nearly identical one. Picture: Charles Linkem

The discovery by former University of California students Adam D. Leaché and Matthew K. Fujita demonstrates the wealth of biodiversity still surviving in the islands of tropical rainforest in West Africa, and the ability of new DNA analysis techniques to distinguish different species, even when they look alike.

‘We tended to find this gecko, Hemidactylus fasciatus, throughout our travels in West Africa,' said Leaché, a herpetologist with UC Berkeley's Museum of Vertebrate Zoology. ‘Despite the fact that it is recognized as one species, using new methods we have established a high probability that it is composed of at least four.'

One of the most endangered areas on Earth
Though the forest fragmentation is part of a long-term drying trend in West Africa, the loss of forest and the resultant impact on the gecko is increasing as a result of human activity, he noted.

‘These rainforests are classified as one of the biodiversity hotspots on the planet, yet they are one of the most endangered areas on Earth,' Leaché said. ‘Human deforestation is accentuating the process of habitat destruction.'

Leaché, currently a post-doctoral fellow at UC Davis but soon to become an assistant professor of biology at the University of Washington, has mounted five expeditions since 2003 to the tropical rain forests of West Africa to survey reptile and amphibian populations.

All of the forest patches are isolated, some requiring hours of hiking to reach, and many are protected in national parks. Access was often difficult because he had to hire porters to carry liquid nitrogen with which to preserve tissue specimens of rare species, plus pickling containers in which to bring home more common animals, including the forest gecko.

ENDANGERED: Kyabobo National Park, Ghana

‘Our intent was to go to remote sites where people haven't done much exploration to try to document biodiversity in Africa,' he said.

Having collected numerous specimens of the 6in gecko, he and Fujita, who accompanied Leaché on several of the expeditions, decided to see whether genetic diversity among the geckos could tell them something about the history of the rainforest belt. That belt stretches nearly 3,000 miles from the coast of Sierra Leone through the Guinean rain forest in Ghana, through Nigeria and Cameroon, to the Congolian rain forest. Over millions of years, the forest has expanded and shrunk with climate change, and an aridification trend over the past several hundred thousand years has caused the forest to contract to mountainous areas, Leaché said.

The park is in the Togo Hills in the Volta Region of the country. (Adam Leaché/UC Berkeley) Leaché and Fujita found sufficient genetic differences among the 50 geckos collected from ten different forest patches to identify four distinct species. The different species were found in different forest patches, suggesting that the species divergence was driven by the isolation of gecko populations from one another after gaps developed in the rainforest.

The details were published in the latest issue of the journal Proceedings of the Royal Society B.