中科院昆明动物所张亚平院士课题组与“百人计划”施鹏研究员合作，提出了与能量供应相关的线粒体基因在不同飞行能力的鸟类中受到了不同的选择压力的科学假说。张亚平院士指导的博士研究生沈永义和孙艳波通过对76个鸟类线粒体全基因组序列的比较和分析，证实了飞翔退化组的鸟类线粒体基因所受到的选择压力显著地小于飞翔组。飞翔能力退化的鸟类，由于不飞行，需要比较少的能量就能维持其运动，因此在飞翔能力退化的鸟类线粒体基因组中，即使发生轻微影响功能的突变，使其产能效率降低，对个体的生存、繁衍没有太大的危害。因此，在飞翔能力退化的鸟类中的选择压力显著地放松，积累了更多的轻微影响功能的突变。
为了进一步揭示这个科学假说的普遍性，他们进一步研究了214个哺乳动物线粒体基因组。同样发现，奔跑运动能力弱的哺乳动物线粒体基因组受到的选择压力比奔跑运动能力强的哺乳动物显著地放松。
该研究揭示了动物系统发育研究中最流行的标记——线粒体基因组的进化并非传统认为的中性进化，物种运动功能相对应的能量需求对线粒体基因组的进化有很重要影响，因为线粒体在能量代谢过程中起关键作用。
具有飞行能力是鸟类区别于其它脊椎动物的最主要特征之一，也是该类群能从残酷的自然界竞争中生存、繁衍的主要原因之一。在现存的鸟类中，飞行能力呈现了多样化。比如：鹰和雕等飞禽具有良好的飞翔能力；与此相反的是企鹅、鸵鸟等鸟类的飞翔能力完全退化，而家鸡，环颈雉和锦鸡等鸟类的飞翔能力部分退化，只能短距离的滑翔飞行。鸟类的飞行是非常耗能的运动，约为动物奔跑所耗能量的3-15倍。而飞行及奔跑所需的能量主要是由细胞内的“能量工厂”线粒体提供的。
该研究论文已在线发表于国际著名杂志《基因组研究》（Genome Research，2008年影响因子10.17）。（生物谷Bioon.com）
生物谷推荐原始出处：
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.
