26 April 2007
Chromosomal Changes Show Effects Of Climate Change
by Kate Melville
Researchers from the University of Oregon (UO) have produced the first chromosomal map showing the regions of mosquito chromosomes that are evolving in response to climate change. Identifying the specific genes that control seasonal development in animals should aid in predicting which animals may be in danger from changing climates and help identify emerging disease-carrying vectors, said William E. Bradshaw and Christina M. Holzapfel, researchers at UO's Center for Ecology and Evolutionary Biology.
Appearing in Genetics, the chromosomal map for the mosquito Wyeomyia smithiiidentifies regions on three chromosomes that respond to length of day (photoperiodism). Two of the chromosomes also have overlapping gene expression that tells the species to go dormant, which they must do to survive. Bradshaw and Holzapfel had previously showed that the mosquito has changed genetically in response to recent, rapid climate change and now uses shorter, more southern day lengths to initiate dormancy.
"We are moving down the track to identify genes that animals use to control their seasonal development," Bradshaw said. "Response to day length is often the primary cue that organisms use for going dormant, and although human beings are not as strongly seasonal as other animals, there are nonetheless seasonal components to our health and welfare just as there are in plants and animals."
The map - containing 900 million DNA base pairs - doesn't explicitly identify which genes drive the mosquito's response, "but it does tell us in what parts of the genome we must look to identify the mechanism of photoperiodism," Bradshaw explained. The map was created using mosquitoes that had developed in precisely controlled environmental rooms that allowed the researchers to simulate climatic conditions occurring in nature anywhere in the world, from the tropics to the polar regions.
"The response to climate warming in animal populations has penetrated to the level of the gene," Bradshaw said. "It affects development, reproduction and dormancy, and this response is occurring in diverse groups of animals from insects to birds and mammals." Holzapfel added that; "plants and animals are not confronting this stress directly, but rather they are flowering, reproducing and going dormant at different times of the year than they used to. Many species will be unable to change quickly enough and will become extinct."
Source: University of Oregon