The mighty tortoises that roam the Galapagos Islands may not have many predators, but a new study suggests that the giant reptiles could run into serious problems due to the diminutive black salt marsh mosquito. Researchers genetically analyzed the mosquito, and found that it was not introduced recently by humans but instead arrived about 200,000 years ago. Since then the insect has evolved so much it is practically a distinct species from the mainland variety. For one thing, the insect has adapted to be able to feast on the blood of lizards, tortoises and other reptiles and not solely on mammals, as it does on the mainland [The New York Times].
That diversity of diet is what has researchers worried. If the black salt marsh mosquito picks up a disease like avian malaria or West Nile fever, it could quickly spread the disease to the Galapagos’s rare tortoises and marine iguanas. Says study coauthor Andrew Cunningham: “With tourism growing so rapidly the chance of a disease-carrying mosquito hitching a ride from the mainland on a plane is also increasing, since the number of flights grows in line with visitor numbers…. If a new disease arrives via this route, the fear is that Galapagos’ own mosquitoes would pick it up and spread it throughout the archipelago” [Telegraph].
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Poor Lonesome George: Although he may have found a mate, researchers say he is still being denied the joys of fatherhood. George is thought to be the last representative of a tortoise subspecies from the Galapagos Island of Pinta, and researchers rejoiced this summer when he appeared to father a batch of eggs. But earlier this week a spokesperson for the Galapagos National Park announced that 80 percent of the eggs do not appear to be viable.
The excitement began this summer when two female tortoises exhibited surprising behavior. The females, who have shared George’s enclosure at the Charles Darwin Research Station on the central island of Santa Cruz for almost 20 years, are of a different but closely related species. After decades of reproductive reticence, they stunned scientists during the summer by building nests and filling them with eggs for the first time [Nature News]. Researchers quickly removed the 16 eggs from the nests and installed them in an artificial incubator, although three of those eggs were thought to have already deteriorated.
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Researchers may be able to recreate a species of giant tortoise that went extinct from the Galapagos Islands with a program of careful breeding. The new possibility hinges on the discovery that a species of giant tortoise living on the biggest island, Isabela, is very similar genetically to the extinct species, Geochelone elephantopus, which vanished from the island Floreana over a hundred years ago.
By mating Isabela tortoises that are most genetically similar to G. elephantopus, selecting the offspring that are most similar and mating those, through successive generations the species’ genetic makeup may be largely restored [The New York Times]. Says lead researcher Gisella Caccone: “We might need three or four generations to do this…. But in theory it could be done, and I think it’s pretty exciting to bring back from the dead a genome that we thought was gone” [BBC News].
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