A mosquito evolving in response to climate change

WASHINGTON (AP) — Researchers have identified for the first time a creature that is evolving in response to global warming. It's a tiny mosquito that lives in the pitcher plant.

Researchers at the University of Oregon in Eugene found that the pitcher plant mosquito, a tiny, fragile species that seldom bothers people, is starting to delay when it breeds and develops.

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The pitcher plant mosquito is not considered a pest. But experts say the study suggests that global warming also could lead to genetic changes in troublesome insects.

The pitcher plant mosquito bases its lifestyle on the length of the day, said William E. Bradshaw of Oregon, the first author of the study appearing Tuesday in the Proceedings of National Academy of Sciences.

When days grow shorter as winter approaches, it is genetically programmed to hibernate, settling in to spend the winter comfortably protected inside the pitcher plant, he said.

However, a subgroup within the pitcher plant mosquito population has slightly different genes that cause them to develop and reproduce later in the season. Global warming, with its longer growing season, thus gives that subgroup a leg up over the other mosquitos through a greater opportunity to leave its genes in the overall population, Bradshaw said

The result is eventual domination of the pitcher plant mosquito population, in what Bradshaw called an evolutionary response to global warming.

The pitcher plant mosquito, which lives mostly on nectar, is found in eastern North America, from Canada to Florida. Along its southern range, it is found as far west as Mississippi.

The pitcher plant mosquito that has adapted to a longer growing season is found mostly in the southern range, Bradshaw said. But the southern adaptation, he said, now is moving north.

In laboratory experiments, the Oregon researchers showed that this genetic adaptation can come to dominate a mosquito population in as little as five years.

The study suggests it is possible that other species may also be in the process of genetically adapting to longer growing seasons, Bradshaw said. Animals with the greatest genetic variability will be the most successful in the face of global climate changes, he said.

"This is an important finding because it shows the genetic population of the mosquito was modified by global warming," said Marina Caillaud, a Cornell University genetic researcher who commented on Bradshaw's paper. "This suggests that this type of genetic adaptation could happen in other species also."

For instance, she said, other mosquitoes that are pests to humans might adapt so that the troublesome mosquito season could grow longer and expand further north.