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Invasive species in a historical context Smithsonian Tropical Research Institute October 13, 2005
Ocean invaders in deep time Much has been made of the economic impacts of recent biological invasions, but what are the implications of invasions in deep time? Luiz Rocha leads geneticists who time travel through ocean environments. The results of their travels, published online in Molecular Ecology, tell us that during warm, interglacial periods, reef-associated fish (goby genus Gnatholepis), leapt around the horn of Africa into the Atlantic, where their range expanded as the world warmed. 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. "We nailed down the timeline of the invasion by sequencing--the last time there was tropical ocean connecting these two areas was 2 million years ago. We calculate that these fish invaded the Atlantic Ocean during a warm period about 150,000 years ago and arrived in the eastern Atlantic only 30,000 years ago." What future effects of climate change might we expect in the marine realm? "Genetic analysis told us that fish from the Indian Ocean breached the Benguela barrier in the past, and this barrier seems to open intermittently. It would be reasonable to expect that other organisms limited by cold water barriers will continue to expand their ranges during warm periods." Ref. Rocha, L.A., Robertson, D.R., Rocha, C., Van Tassell, J.L., Craig, M.T., Bowen, B.W. 2005. Recent invasion of the tropical Atlantic by an Indo-Pacific coral reef fish. Molecular Ecology online. Smithsonian Tropical Research Institute
Science Interpreter Smithsonian Tropical Research Institute Panama City, Panama tel +507 212-8216 kingb (at) tivoli.si.edu US (202) 786-2094 ext. 8216 fax +507 212-8148 US (202) 786-2094 ext. 8148 This is a modified news release from the Smithsonian Tropical Research Institute.
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