An Evolving Partnership UO Biologists Bradshaw and Holzapfel Catch International Attention for Mosquito Discovery

Christina Holzapfel and William Bradshaw Within the last thirty years, questions about global warming have come to the forefront — and so has the work of William Bradshaw and Christina Holzapfel, members of the UO’s Department of Biology since 1971. “The earth has warmed faster in the last thirty years than at any time over the last 1,000 years,” says Bradshaw. “Many plants and animals now bloom, migrate, or reproduce earlier than they did thirty years ago.” In the first study of its kind, Bradshaw and Holzapfel, working in the Ecology and Evolution program, provide scientific evidence that a type of mosquito is changing genetically in response to global warming. Their study, which appeared as the cover article in the scientific journal Proceedings of the National Academy of Science, demonstrates that the pitcher plant mosquito is postponing hibernation as the growing seasons become longer. Bradshaw and Holzapfel have collaborated in research since graduate school at the University of Michigan. Bradshaw’s interest was in physiology and ecology while Holzapfel leaned more toward evolution and systematics. However, a common background in insects and biological clocks laid the foundation for this married couple’s research. Supported by the National Science Foundation (NSF) for over thirty years, this research team has taken several sabbaticals together, traveling to Florida, Canada, and Europe to collect mosquitoes and bring them back to their lab. But global warming was never an object of their research. “Nobody set out to test for the effects of global warming thirty years ago,” says Holzapfel. “It was simply a non-issue.” However, after two decades of data collection, Bradshaw and Holzapfel began to wonder: “Has there been adaptive evolution in response to global warming?” When they compared the mosquito population collected in 1996 to their 1972 counterparts, they discovered that yes, the pitcher plant mosquito had genetically altered its life cycle in response to longer summers and shorter winters. Even more surprising was that, in comparing mosquito populations between 1988 and 1993, they found that evolutionary adaptation could occur in a time span as short as five years. “This is evolution happening at a breakneck speed,” says Bradshaw. And the mosquito adaptations have important implications for other biological creatures as well. “A wide variety of plants and animals use the length of day, or photoperiod, as a pivotal environmental cue,” he explains. If the pitcher plant mosquito is adapting to longer growing seasons, then there is good reason to believe that the seasonal patterns of dormancy, migration, development, and reproduction may be changing in other insects, animals, and plants. Researchers are also considering how global warming might aid the spread of insect-borne diseases, such as malaria. Portions of the southern United States and Europe are formerly malaria-endemic regions and a longer growing season could eventually spread the disease further into North America. “Global warming is already permitting a wider impact of dengue, yellow fever, and other viral diseases in North America,” says Holzapfel. Delicate ecosystems may also be affected. Some species of songbird have shown signs of decline because their offspring arrival had previously coincided with the development of their insect food, guaranteeing it an adequate food supply. A major effect of global warming is going to be the disruption of such seasonal interactions, predict the researchers. So, it turns out that this tiny bug may have very big applications to environmental policy. “Since we’ve now shown that genetic change can occur in response to recent environmental change, politicians and environmentalists have keen interest in our results,” says Holzapfel. The findings have been publicized internationally — in the London Times, New York Times, Scientific American, and Nature to name a few. Such coverage, along with publication in PNAS, has brought greater visibility to the Biology Department’s Ecology and Evolution Program and will likely attract even more graduate students and faculty who want to participate in ecological research at the UO. The lab’s success also reflects the hard work of many undergraduates. Bradshaw and Holzapfel consider student training to be part of their job as researchers. In weekly meetings, students go over the progress of their projects, ask questions about experimentation in general, and sometimes even seek opinions on graduate school or world news. Brian Haggerty, a senior in Biology, is one of ten undergraduates currently working alongside Bradshaw and Holzapfel. “Bill and Chris have allowed me to test my own curiosities as well as theirs, using lab space to set up my own experiments,” says Haggerty. “While the theories and raw experiments have been thought up by Bill and Chris, they leave it up to me to plan the project, maintain the integrity of every aspect of the work, and manage the research from start to finish.” Bradshaw and Holzapfel ask their students to think critically and pose questions beyond what the research itself demands. “Consistent hard work, although usually required, is not itself sufficient to guarantee results,” says Holzapfel. Challenged by the research, Brian Haggerty says that his curiosity about the world has grown tremendously in the three years he’s worked in the lab. Scott Stevens, another undergraduate research assistant, says that the experience has “put the biology within a tangible framework, making it easier to understand that the idea of ‘consequence’ is not just theory.” As mentors, Bradshaw and Holzapfel serve the scientific community twofold: through their research and through the thoughtful training of our next generation of scientists.

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