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Inter Press Service (IPS)

Climate Change Also Drives Evolution

22 May 2007

New scientific evidence confirms that human action, such as carbon emissions causing global warming, and industrial-scale search for food, is decimating biodiversity - and, in some cases, is driving threatened species to evolve and adapt at unexpected speed to new living conditions.

An example of this evolution accelerated by human action is the new sexual behaviour of codfish, says the Austrian biologist Ulf Dieckmann, an evolution and ecology researcher at the International Institute for Applied Systems Analysis (IIASA), near Vienna.

According to Dieckmann, codfish has within a couple of decades adapted to new age structure within its own species, provoked by fishery.

Until some decades ago, codfish reached sexual maturity at the age of 10, and only when it measured at least one metre. Now, codfish reaches sexual maturity at the age of six, and when it measures only 65 centimetres, Dieckmann told IPS.

"Some fish species have the capability to adapt to modern living conditions within a very short period of time," Dieckmann said. "Given that large-scale fishery hunts especially the larger and older (codfish) exemplars, the survival of the species rests upon the younger animals," he added.

Dieckmann has been observing codfish behaviour for several years. "Industrial fishery has decimated codfish, and one consequence of this is that there is more food for less fish in the seas," he said. "That’s why the younger fish exemplars are growing more quickly, and reach sexual maturity in earlier years."

"You can simply say: If a fish waits too long to procreate, it might be too late, either because the fish has been caught in a net, or because younger competitors have already taken this function over," Dieckmann pointed out.

Dieckmann’s findings have been corroborated elsewhere. Biologist David Reznick of the University of California, observed a similar evolutionary process among guppies, a small, freshwater fish, often kept in aquariums.

Reznick observed that if the oldest guppies are retired from a population, their sexual places are occupied by younger exemplars. Since guppies grow more quickly than codfish, the process of evolution occurs within five years, while the adaptation by codfish to new age structure within the population can take as much as 40 years.Read more

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