?西班牙的研究人员发现气候变化导致了果蝇物种的基因变化。
??西班牙巴塞罗纳大学的该项研究发现：美洲的一种果蝇（Drosophila subobscura）在一段时间内染色体发生了倒置，这种果蝇起源于欧洲，大约25年前被引入北美洲和南美洲。
??科学家们分别研究了最近和几十年前采自于欧洲，以及1981年和1999年采自于北美洲、1985年和2002年采自于南美洲的果蝇样品。华盛顿大学的生物学教授Raymond Huey与人合作了一篇文章阐述了该项研究结果，他表示：这三个地点的果蝇都记录了不同的染色体倒置，这所有的变化似乎都是为了抵御更温暖的气候——在采集初始样品时起全球各地就纷纷出现的气候变化现象。
??Huey称：从长远观点来看，这表明气候变暖已经影响到了生物基因，至少对果蝇这些生物产生了影响。好消息就是这些果蝇能够适应这些气候变暖，至少某种程度上能够适应。然而，繁衍周期更长的生命体，例如人类或者美洲杉可能就不会这么欣然接受了。
??该项研究发表在8月31日的《科学快讯》杂志在线版上。
英文原文：
Climate change drives genetic changes
Global warming is driving worldwide genetic changes in a fly species, scientists reported online August 31 in Science.
These findings reinforce recent studies suggesting that climate change is rapidly leading to genetic impacts "in widespread organisms," Ary Hoffmann at the University of Melbourne in Australia, who did not participate in this study, told The Scientist.
Raymond Huey at the University of Washington in Seattle, along with his colleagues in Spain and Virginia, analyzed Drosophila subobscura, a fruit fly native to Europe. The species was accidentally introduced to Chile in the 1970s and the West Coast of the United States in the 1980s, probably via cargo ships.
The researchers investigated chromosomal inversions, where chromosomal segments flip themselves backward. The first chromosomal inversion samples in D. subobscura were collected in Europe more than 40 years ago. After the fly spread to other continents, geneticists began sampling chromosomal inversion data in South America in 1981 and in North America in 1985.
Past research discovered chromosomal inversions in the fly that were common at low latitudes, where climates are warmer, but uncommon in the lower temperatures of high latitudes, suggesting chromosomal inversions help flies adjust to changes in climate.
To see if global climate warming had any impact on genetics, Huey and his colleagues compared the existing decades of genetic data, gathered over an average of 24 years, with temperature records for the same time periods. In 22 of 26 fly populations examined across three continents, climate warmed over the intervals. Among those 22 populations that experienced warming, the frequency of chromosomal changes characteristic of low latitudes and warmer climates increased in all but one population.
"What is most surprising is that small shifts in average temperature, about ½ degrees C, which seems trivial on a temperature scale, are obviously not trivial to the flies," Huey told The Scientist. "They are immersed in this warmer environment, such that the effect of climate warming is likely compounding over their life span."
Inversions involve large segments of chromosomes and thus many genes, which "makes it hard to determine which particular traits, or groups of co-adapted traits, might be under selection. Trying to figure that out is a goal for the future," Huey said.
Past studies of genetic changes in response to global warming only looked at populations of a species that were distributed over a single continent, at most, Huey said. "Here you have a single species, each interacting with their environments with the same genome over several continents, to help show how global a response this is," William Bradshaw at the University of Oregon in Eugene, not a coauthor, told The Scientist.
These genetic shifts appeared rapid, detectable even for samples from an area taken less than 20 years apart. Future research should investigate the different rates and extents to which species are evolving in response to climate change, Christina Holzapfel at the University of Oregon in Eugene, who did not participate in this study, told The Scientist.
While these and other findings suggest small species with big populations and high reproductive rates can keep up with climate change, many other species might not. Researchers in the Netherlands show birds like the Great Tit are changing, but perhaps not fast enough, "and large organisms might not keep up at all," Holzapfel said. "The organisms most likely to keep up aren't necessarily those we'd like to, like mosquitoes and pathogens," Bradshaw added. The resulting collapse of populations "is the real specter of climate change," Huey said.
Charles Q. Choi
cchoi@the-scientist.com
Links within this article
J. Balanya et al. "Global genetic change tracks global climate warming in Drosophila subobscura." Science, published online ahead of print August 31, 2006.
