蝙蝠是翼手目動物的通稱,，是唯一演化出具有真正飛行能力的哺乳動物。跟鳥類進(jìn)化出飛行能力一樣,，蝙蝠飛行能力的進(jìn)化需要一系列十分復(fù)雜的形態(tài)和生理變化,，因此達(dá)爾文在《物種起源》中感嘆“從不能飛的原始哺乳動物進(jìn)化為能飛的蝙蝠是不可思議的”。
中國科學(xué)院昆明動物研究所張亞平院士及其指導(dǎo)的博士生沈永義注意到飛行消耗的能量是奔跑3-15倍,。因此,，飛行除了需要骨骼等形態(tài)變化外，還需要能量供應(yīng)系統(tǒng)的高效率化,，以便能適應(yīng)能量需求的急劇增加,。通俗的比喻就是飛機(jī)能飛，不單單需要機(jī)翼等形態(tài)結(jié)構(gòu),，還需要有強(qiáng)大的發(fā)動機(jī)來提供動力,。線粒體是細(xì)胞的能量工廠,，通過氧化呼吸鏈提供了生物體95%的能量，是動物各種運(yùn)動所需能量動力的“發(fā)動機(jī)”,。因此他們推測線粒體產(chǎn)能系統(tǒng)的進(jìn)化應(yīng)該與蝙蝠飛行能力的起源密切相關(guān),。通過全基因組比較分析，他們證實(shí)在蝙蝠飛行能力的起源過程中,，線粒體的氧化呼吸鏈基因受到正選擇,，線粒體與細(xì)胞核編碼的基因發(fā)生協(xié)同進(jìn)化，以適應(yīng)飛行起源過程中對能量需求的急劇增加,。
該研究成果于4月26日在國際著名刊物美國《國家科學(xué)院院刊》（PNAS）在線發(fā)表,。美國科學(xué)院院士David M. Hillis評價(jià)道：“該研究十分出色且令人興奮，該研究結(jié)果對了解線粒體的分子生物學(xué)和進(jìn)化,，以及飛行的分子適應(yīng)機(jī)制有廣泛的意義”,。
有趣的是，該研究團(tuán)隊(duì)2009年通過對飛行能力健全與退化的鳥類的比較研究,，在Genome Research發(fā)表的姐妹篇工作揭示,，線粒體基因組的選擇壓力與動物運(yùn)動能力密切相關(guān)。（生物谷Bioon.com）
相關(guān)閱讀：Genome Research：線粒體基因組的選擇壓力與動物運(yùn)動能力相關(guān)
生物谷推薦原文出處：
PNAS doi: 10.1073/pnas.0912613107
Adaptive evolution of energy metabolism genes and the origin of flight in bats
Yong-Yi Shena,b,c, Lu Lianga,c, Zhou-Hai Zhub, Wei-Ping Zhoua,d, David M. Irwine,f, and Ya-Ping Zhanga,b,1
Bat flight poses intriguing questions about how flight independently developed in mammals. Flight is among the most energy-consuming activities. Thus, we deduced that changes in energy metabolism must be a primary factor in the origin of flight in bats. The respiratory chain of the mitochondrial produces 95% of the adenosine triphosphate (ATP) needed for locomotion. Because the respiratory chain has a dual genetic foundation, with genes encoded by both the mitochondrial and nuclear genomes, we examined both genomes to gain insights into the evolution of flight within mammals. Evidence for positive selection was detected in 23.08% of the mitochondrial-encoded and 4.90% of nuclear-encoded oxidative phosphorylation (OXPHOS) genes, but in only 2.25% of the nuclear-encoded nonrespiratory genes that function in mitochondria or 1.005% of other nuclear genes in bats. To address the caveat that the two available bat genomes are of only draft quality, we resequenced 77 OXPHOS genes from four species of bats. The analysis of the resequenced gene data are in agreement with our conclusion that a significantly higher proportion of genes involved in energy metabolism, compared with background genes, show evidence of adaptive evolution specific on the common ancestral bat lineage. Both mitochondrial and nuclear-encoded OXPHOS genes display evidence of adaptive evolution along the common ancestral branch of bats, supporting our hypothesis that genes involved in energy metabolism were targets of natural selection and allowed adaptation to the huge change in energy demand that were required during the origin of flight.
