中科院昆明動物所張亞平院士課題組與“百人計劃”施鵬研究員合作,，提出了與能量供應(yīng)相關(guān)的線粒體基因在不同飛行能力的鳥類中受到了不同的選擇壓力的科學(xué)假說,。張亞平院士指導(dǎo)的博士研究生沈永義和孫艷波通過對76個鳥類線粒體全基因組序列的比較和分析,，證實了飛翔退化組的鳥類線粒體基因所受到的選擇壓力顯著地小于飛翔組,。飛翔能力退化的鳥類，由于不飛行,，需要比較少的能量就能維持其運動,，因此在飛翔能力退化的鳥類線粒體基因組中，即使發(fā)生輕微影響功能的突變,，使其產(chǎn)能效率降低,，對個體的生存、繁衍沒有太大的危害,。因此,，在飛翔能力退化的鳥類中的選擇壓力顯著地放松，積累了更多的輕微影響功能的突變,。
為了進(jìn)一步揭示這個科學(xué)假說的普遍性,，他們進(jìn)一步研究了214個哺乳動物線粒體基因組。同樣發(fā)現(xiàn),，奔跑運動能力弱的哺乳動物線粒體基因組受到的選擇壓力比奔跑運動能力強的哺乳動物顯著地放松,。
該研究揭示了動物系統(tǒng)發(fā)育研究中最流行的標(biāo)記——線粒體基因組的進(jìn)化并非傳統(tǒng)認(rèn)為的中性進(jìn)化，物種運動功能相對應(yīng)的能量需求對線粒體基因組的進(jìn)化有很重要影響,，因為線粒體在能量代謝過程中起關(guān)鍵作用,。
具有飛行能力是鳥類區(qū)別于其它脊椎動物的最主要特征之一，也是該類群能從殘酷的自然界競爭中生存,、繁衍的主要原因之一,。在現(xiàn)存的鳥類中，飛行能力呈現(xiàn)了多樣化,。比如：鷹和雕等飛禽具有良好的飛翔能力；與此相反的是企鵝,、鴕鳥等鳥類的飛翔能力完全退化,，而家雞，環(huán)頸雉和錦雞等鳥類的飛翔能力部分退化,，只能短距離的滑翔飛行,。鳥類的飛行是非常耗能的運動，約為動物奔跑所耗能量的3-15倍,。而飛行及奔跑所需的能量主要是由細(xì)胞內(nèi)的“能量工廠”線粒體提供的,。
該研究論文已在線發(fā)表于國際著名雜志《基因組研究》（Genome Research，2008年影響因子10.17）,。（生物谷Bioon.com）
生物谷推薦原始出處：
Genome Research Published in Advance July 17, 2009, doi:10.1101/gr.093138.109
Relaxation of selective constraint on avian mitochondrial DNA following the degeneration of flight ability
Yongyi Shen, Peng Shi, Yan-Bo Sun and Ya-ping Zhang,1
Kunming Institute of Zoology
The evolution of flight is the most important feature of birds, and this ability has helped them become one of the most successful groups of vertebrates. However some species have independently lost their ability to fly. The degeneration of flight ability is a long process, and some species remain transitional locomotive models. Most of the energy required for locomotion is supplied by mitochondria via oxidative phosphorylation. Thus, rapidly flying birds should require a more energy efficient metabolism than weakly flying or flightless species. Therefore, we speculated that evolutionary constraints acted on the mtDNA of birds with different locomotive abilities. To test this hypothesis, we compared 76 complete avian mitochondrial genomes. Weakly flying and flightless birds, compared to rapidly flying birds, accumulated more nonsynonymous nucleotide substitutions relative to synonymous substitutions. Even after controlling for mutation rate, this trend remained significant. This finding was further tested for its generality by examining 214 complete mammalian mitochondrial genomes. The same as birds, a negative correlation was also found for the Ka/Ks ratio and locomotive speed. Our results demonstrated that, in addition to the previously described role for effective population size, functional constraints due to locomotion play an important role in the evolution of mtDNA.
