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.


“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. “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.”

Media Contact

Beth King EurekAlert!

More Information:

http://www.si.edu

All latest news from the category: Ecology, The Environment and Conservation

This complex theme deals primarily with interactions between organisms and the environmental factors that impact them, but to a greater extent between individual inanimate environmental factors.

innovations-report offers informative reports and articles on topics such as climate protection, landscape conservation, ecological systems, wildlife and nature parks and ecosystem efficiency and balance.

Back to home

Comments (0)

Write a comment

Newest articles

Lighting up the future

New multidisciplinary research from the University of St Andrews could lead to more efficient televisions, computer screens and lighting. Researchers at the Organic Semiconductor Centre in the School of Physics and…

Researchers crack sugarcane’s complex genetic code

Sweet success: Scientists created a highly accurate reference genome for one of the most important modern crops and found a rare example of how genes confer disease resistance in plants….

Evolution of the most powerful ocean current on Earth

The Antarctic Circumpolar Current plays an important part in global overturning circulation, the exchange of heat and CO2 between the ocean and atmosphere, and the stability of Antarctica’s ice sheets….

Partners & Sponsors