Skeeter Heater Mosquitoes adapt to global warming. BY KERA ABRAHAM It's not even a debate anymore: Global warming is changing life on Earth. Today's cutting-edge research focuses not on whether climate change is happening, but on how it will affect various species — which will adapt and which will perish, and over what time frame. Illutration by Hanif Panni Some species seem resilient to rising temperatures. Scientists have shown that several kinds of European birds and butterflies have responded to global warming by moving north into places that were too cold for them a century ago. And certain fungi have thrived in the warmer temperatures caused by global warming. But what's great for some species, like fungi, may be deadly to others, like frogs. A study recently published in the journal Nature blames global warming for nurturing parasitic fungi that may have doomed as many as 65 Central and South American frog species. Another study in Nature predicts that global warming will push more than a million species toward extinction by 2050. As huge a topic as global warming is, leaps in understanding can happen in small places — even here in Eugene, in a lab on the UO campus, where evolutionary geneticists Christina Holzapfel and William Bradshaw test how mosquitoes respond to various light conditions. Holzapfel and Bradshaw, who are partners in life as well as the lab, have been doing research on mosquitoes for more than 30 years. Their discovery that mosquitoes at higher altitudes behave like their cousins further north made the cover of Nature in 1976. In 2001 the couple made another major discovery, one significant enough to warrant mention in The New Yorker, National Geographic, Scientific American and BBC News. They found that populations of Wyeomyia smithii, a non-biting mosquito that lives in the water-filled leaves of a carnivorous pitcher plant, have genetically responded to a changing climate. It was the first study to show that global warming is actually driving evolution. Wyeomyia smithii get busy all through the growing season, sometimes reproducing through five or six generations in a few months. But at some critical point near the end of the summer, the larvae go dormant, and they remain in that state (called diapause) through the winter, emerging from the leaves as adults in the spring. How do the mosquito larvae "know" when to go dormant? They use genetic cues that are sensitive to day length. For example, about half of the W. smithii larvae in Manitoba, Canada, go dormant when the day is 15 hours and 17 minutes long, around Aug. 14. But move south to Florida and the mosquitoes party longer, eating late-summer nectar and having sex until the day is only 12 hours and 9 minutes long, around Oct. 21. (Like human party-goers, some "crash out" a little earlier than the majority and some a little later, depending on their genes.) Bradshaw and Holzapfel found that W. smithii populations are now going dormant later than they were 30 years ago. The Manitoba population that now enters diapause around Aug. 14, did so around Aug. 5 in 1975. That told the researchers that nature is selecting for the individual mosquitoes that stay awake through the end of the party, taking advantage of the longer growing season brought about by global warming. And those that enter diapause too early die at higher rates, giving new meaning to the phrase, "You snooze, you lose." The good news — for insects and bacteria at least — is that some species may be able to successfully adapt to climate change. The bad news — especially for slow-evolving critters such as polar bears and humans — is the implication that "having the wrong genetically pre-disposed reaction to the day length is very seriously bad for you," as Bradshaw put it. You might think that Bradshaw and Holzapfel's discovery would send an alarm to policy-makers to start taking global warming very seriously. But the researchers make a clear distinction between policy and science, and they choose their words on the subject carefully. "I feel as scientists that we shouldn't work in an advocacy role for either side of the global warming debate," Bradshaw said. "But I feel that the more you understand something, the better you can plan for it. We have shown that evolutionary response to global warming is a reality." Holzapfel is more blunt. "As the world warms, discordance in communities is going to become immense," she said, her big blue eyes magnified by round plastic glasses. "It's hard to envision how something good can come out of major disorganization."
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