Yale Bulletin and Calendar

August 26, 2005|Volume 34, Number 1

Galapagos tortoises more diverse
than once believed, say scientists

Almost 150 years after Charles Darwin proposed a mechanism for biological evolution, previously unrecognized diversity has been discovered among the giant tortoises of the Galápagos, Geochelone nigra, whose distinctiveness was an inspiration in formulating the theory of natural selection.

The new taxon (species or sub-species) of Galápagos tortoise was characterized by a team of scientists led by three scientists from Yale's Department of Ecology and Evolutionary Biology: postdoctoral associate Michael Russello, senior research scientist Adalgisa Caccone and professor Jeffrey Powell.

Conservation of the Galápagos tortoises' habitat is an immediate concern because the human population on the island of Santa Cruz is growing rapidly, according to the scientists. The team emphasized the importance of accurate taxa identification for effective conservation policy and preservation of genetic diversity in a recent report in Biology Letters published by the Royal Society of London.

The current tortoise populations on the island of Santa Cruz, long believed to comprise a single taxon, are in fact, three genetically distinct lineages that are yet to be formally named, according to the researchers.

While visible characteristics, like the shapes of their shells, were the basis for previous classification of the tortoises, this research team used a variety of molecular genetic and analytical tools including mitochondrial DNA analysis from extinct taxa. The comprehensive study of these tortoises throughout Galápagos made their discovery possible.

Currently 11 of the recognized 15 taxa of tortoise are living, and they continue to be endangered throughout the Galápagos. Only 2,000 to 4,000 individual tortoises remain on Santa Cruz, and there may be as few as 100 individuals of the new taxon.

"It is ironic that while Santa Cruz has the largest population of tortoises, it also has the largest human population -- projected to double in the next eight years -- which is their greatest source of endangerment," says Russello. "Since accurate taxonomy is crucial for effective conservation policy, these results have fundamental importance for preserving the genetic and taxonomic diversity of these historically significant reptiles."

Collaborators included Scott Glaberman of Yale, James P. Gibbs of the State University of New York at Syracuse and Cruz Marquez of the Charles Darwin Research Station, Santa Cruz, Ecuador. The study was funded through the ECOSAVE project of the Yale Institute for Biospheric Studies and a National Geographic grant.

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Private portrait miniatures showcase the faces of public figures

Gallery hosting festive open house . . .

Architecture gallery to feature traveling art show 'Ant Farm'

Sterling Library launches new academic year with two exhibits

Researchers create powerful tool for decoding gene functions

Galapagos tortoises more diverse than once believed, say scientists

Team identifies 'signatures' of protons in water

'Canary Database' shows animals offer health warnings for humans

Team digitally reconstructs long-extinct 'Lamp Shell'

'Gene trapping' reveals how flower development is controlled

Discovery may aid development of treatment for melanoma

Drinking alcohol may lower risk of non-Hodgkin's lymphoma

Lyme disease prevention program launched in Connecticut

For 35 students, summer was a time of service in New Haven

IN MEMORIAM

John Ostrom: He revolutionized field of paleontology

Robert Abelson: Psychologist was adviser to presidential candidates

Greer Allen: University printer was inspiration to School of Art students