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Invasive species may increase with global warming mongabay.com October 13, 2005
New research published in Molecular Ecology suggests that climate change could trigger the expansion of invasive species into wider ranges. The study looked at the genetic history of a goby species in the Eastern Atlantic which appears to have expanded its range dramatically when the world warmed about 150,000 years ago. Why are invasive species so destructive? While ninety percent of immigrant species do no obvious harm to their new home environment, a small number do disproportionate damage. By definition, "invasive species" are "an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health" (U.S. Executive Order 13112). Invasive species disrupt ecosystems primarily by preying on local species and competing with native species over limited resources. The effect on native biodiversity can be severe -- the Cornell study says that 42% of the species on the Threatened or Endangered species lists are at risk primarily because of non-indigenous species. Introduced tilapia and Nile Perch have devastated endemic fish populations throughout Africa, while the snakehead, a carnivorous fish capable of walking across land, has raised fears every time it appears in a pond in the Eastern United States. Further, there can be significant economic costs to the damage caused by such aliens. For example, removing the zebra mussel from the Great Lakes alone will cost $5 billion.
A warmer climate could mean more foreign tropical species could find their way to, and thrive in, the United States. Florida and Hawaii, the country's two most tropical states, have arguably suffered the most from invasive species. The python, a species of snake that has invaded the Everglades after pet owners have released it into the wild, has recently made headlines as it battles native alligators at the top of the food chain. Dramatic battles aside, the ecological and economic threat from invasive species is real and should serve as a reminder to what's in store for a warmer world.
Ocean invaders in deep time Smithsonian Tropical Research Institute October 13, 2005 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 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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