Last year researchers realized they'd managed to overlook an entire species of elephants: African forest- and savannah-dwelling types, they found, are not one species but two. Now another team says yet a new division is needed. They argue that elephants of both types from West Africa form a third, genetically distinct group.
Scientists have long debated the distinctions among African elephants, which were divided into as many as 18 types in colonial times, says conservation geneticist Lori Eggert of the Smithsonian Institution in Washington, D.C. More recently they were lumped together as a lone species, Loxodonta africana. That was until researchers provided genetic evidence that the shy, forest-dwelling type was a distinct species, Loxodonta cyclotis (ScienceNOW, 23 August 2001).
Last year's study didn't include data from West Africa, however, where species relatedness has been hotly debated. Eggert studies elusive elephants in Ghana, Mali, and Cameroon by extracting DNA from dung. Interested in how her study subjects fit into the elephant family tree, she collected samples from savannah and forest elephants in both West and central Africa. Along with colleagues from the University of California, San Diego, Eggert extracted genetic material and compared sequences of one gene and five other strips of DNA among these populations. To the researchers' surprise, forest elephants in the west were genetically distinct from forest-dwellers in central Africa.
Once the researchers found evidence that the forest type wasn't a single group, they collected additional published DNA sequences for elephants continent-wide. The team compared these sequences and came to another surprising conclusion: The savannah and forest elephants of West Africa--despite physical differences--appear to be a single population. The findings were published online 12 September in the Proceedings of the Royal Society, B.
The data suggest more genetic distinctiveness between populations across the continent than the previous study, says Samuel Wasser, a conservation biologist at the University of Washington, Seattle. He cautions, however, that the data are not conclusive enough to settle the issue once and for all. Wasser believes, for instance, that with more detailed testing, savannah and forest elephants in West Africa might prove to be distinct from one another.
Related sites
Smithsonian genetics
lab
WWF African elephant conservation statistics
The Elephants of
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