"We found that global warming events correspond clearly with major range expansions of gobies from the Indian Ocean into the Atlantic Ocean and subsequently into the Eastern Atlantic," summarizes Rocha. A chilly Antarctic current--the Benguela upwelling system-- surges up along the western coast of Africa acting as a natural barrier, and has prevented most warm water organisms from the Indian Ocean from making it in to the Atlantic for the last 2 million years. But when the world warmed about 150,000 years ago, gobies slipped around the corner of the continent.
Researchers at the Smithsonian Tropical Research Institute, Scripps Institution of Oceanography, Hofstra University and the University of Hawaii, sequenced goby DNA (774 pb of the mtDNA of cytochrome b, to be exact) from the western, central and eastern Atlantic Ocean. They also sequenced DNA from gobies in the same genus from South Africa, from the Cocos Keeling Islands in the eastern Indian Ocean, and from the Cook Islands in the South Pacific. They calculate the approximate amount of time that isolated groups of fish have been separate based on the differences in the DNA between groups.
What evidence do they have that makes them think that Atlantic gobies are invaders? "The Atlantic goldspot goby certainly is a prime candidate-it's the only species of the genus in the Atlantic and there are eight species and subspecies in the Indo-Pacific. It's really similar to a sister taxon in the Indian Ocean," Rocha continues. "
Contact: Beth King
Smithsonian Tropical Research Institute