隨著全球氣候變暖，相比其它物種而言,，人們更多地是擔(dān)憂北極熊和企鵝的生存狀況。然而一份最新的研究表明,，全球變暖有可能對數(shù)量占到全球物種一半以上的熱帶物種造成更大的災(zāi)難,。相關(guān)論文5月5日在線發(fā)表于美國《國家科學(xué)院院刊》（PNAS）上,。
氣候變化模型認(rèn)為，極地附近溫度的上升幅度要比赤道附近的大,。由于這個原因,，科學(xué)家之前猜測熱帶物種遭受氣候變化的影響要小一些。
最新的研究表明,，這個猜測是完全錯誤的,。研究領(lǐng)導(dǎo)者、美國加州大學(xué)洛杉磯分校的海洋學(xué)家Curtis Deutsch表示,，由于熱帶一年之內(nèi)的溫度要比高維度地區(qū)更穩(wěn)定一些,，所以熱帶生物，特別是昆蟲等冷血動物,，能夠應(yīng)付的溫度范圍很窄,。這樣一來，即使是較小的升溫,，它們對溫度變化的強(qiáng)烈敏感性也會將它們置于危險的境地,。
Deutsch和同事查閱了以前的相關(guān)文獻(xiàn)，找到了38種昆蟲的實驗室數(shù)據(jù),，包括蝴蝶,、甲蟲等，這些昆蟲分布范圍從北緯50度至南緯40度,。研究人員根據(jù)氣候變化模型,，預(yù)測了這些昆蟲收集地2100年的溫度。他們將預(yù)測的未來溫度加入到這些昆蟲的種群生長曲線上,，結(jié)果發(fā)現(xiàn),，距今約100年后，熱帶昆蟲的繁殖率比今天減慢了大約20%,。在另一方面,，高維度昆蟲的繁殖率卻增加了。而降低的繁殖率有可能導(dǎo)致多種熱帶昆蟲的滅絕,，除非它們進(jìn)行適應(yīng)或遷移,。Deutsch說，最終的結(jié)果將依賴于生態(tài)變化的層疊效應(yīng),，“結(jié)果如何很難預(yù)測,。”
美國杜克大學(xué)的保護(hù)生物學(xué)家Stuart Pimm認(rèn)為，這一研究很有思想性,。不過他主張,，一個物種的存活與否最終更多地要依賴于它遷離開高溫度區(qū)域的能力，而不是忍受的能力。
英國約克大學(xué)的保護(hù)生物學(xué)家認(rèn)為這一研究是一種號召,，以呼吁更多的人進(jìn)行熱帶研究,。他說，“如果即將出現(xiàn)大滅絕危機(jī)的話,，我們應(yīng)該開始提出證明”,，只有牢靠的滅絕證據(jù),，而不是預(yù)測,，才能刺激氣候變化政策的轉(zhuǎn)變。（科學(xué)網(wǎng) 梅進(jìn)/編譯）
生物谷推薦原始出處：
（PNAS）,，doi：10.1073/pnas.0709472105,，Curtis A. Deutsch，Paul R. Martin
Impacts of climate warming on terrestrial ectotherms across latitude
Curtis A. Deutsch*,,, Joshua J. Tewksbury,, Raymond B. Huey, Kimberly S. Sheldon, Cameron K. Ghalambor¶, David C. Haak, and Paul R. Martin,||
*Program on Climate Change and Department of Oceanography and Department of Biology, University of Washington, Seattle, WA 98195; and ¶Department of Biology and Graduate Degree Program in Ecology, Colorado State University, Fort Collins, CO 80523
Edited by David B. Wake, University of California, Berkeley, CA, and approved March 3, 2008 (received for review October 4, 2007)
Abstract
The impact of anthropogenic climate change on terrestrial organisms is often predicted to increase with latitude, in parallel with the rate of warming. Yet the biological impact of rising temperatures also depends on the physiological sensitivity of organisms to temperature change. We integrate empirical fitness curves describing the thermal tolerance of terrestrial insects from around the world with the projected geographic distribution of climate change for the next century to estimate the direct impact of warming on insect fitness across latitude. The results show that warming in the tropics, although relatively small in magnitude, is likely to have the most deleterious consequences because tropical insects are relatively sensitive to temperature change and are currently living very close to their optimal temperature. In contrast, species at higher latitudes have broader thermal tolerance and are living in climates that are currently cooler than their physiological optima, so that warming may even enhance their fitness. Available thermal tolerance data for several vertebrate taxa exhibit similar patterns, suggesting that these results are general for terrestrial ectotherms. Our analyses imply that, in the absence of ameliorating factors such as migration and adaptation, the greatest extinction risks from global warming may be in the tropics, where biological diversity is also greatest.
