Department of Biology and Museum of Southwestern Biology, University of New Mexico, , Albuquerque, NM 87131, USA, Department of Integrative Biology, University of Guelph, , Guelph, Ontario, Canada , N1G 2W1.
Proc Biol Sci. 2014 Jan 29;281(1779):20132780. doi: 10.1098/rspb.2013.2780. Print 2014 Mar 22.
The tendency for flying organisms to possess small genomes has been interpreted as evidence of natural selection acting on the physical size of the genome. Nonetheless, the flight-genome link and its mechanistic basis have yet to be well established by comparative studies within a volant clade. Is there a particular functional aspect of flight such as brisk metabolism, lift production or maneuverability that impinges on the physical genome? We measured genome sizes, wing dimensions and heart, flight muscle and body masses from a phylogenetically diverse set of bird species. In phylogenetically controlled analyses, we found that genome size was negatively correlated with relative flight muscle size and heart index (i.e. ratio of heart to body mass), but positively correlated with body mass and wing loading. The proportional masses of the flight muscles and heart were the most important parameters explaining variation in genome size in multivariate models. Hence, the metabolic intensity of powered flight appears to have driven genome size reduction in birds.
飞行生物倾向于拥有小基因组，这被解释为自然选择作用于基因组物理大小的证据。然而，在一个飞行类群内进行的比较研究尚未很好地确立飞行基因组的联系及其机制基础。是否存在某种特定的飞行功能方面，如快速新陈代谢、升力产生或机动性，会影响基因组的物理大小？我们从一组在系统发育上多样化的鸟类物种中测量了基因组大小、翅膀尺寸以及心脏、飞行肌肉和身体质量。在系统发育控制的分析中，我们发现基因组大小与相对飞行肌肉大小和心脏指数（即心脏与体重的比值）呈负相关，但与体重和翼载荷呈正相关。飞行肌肉和心脏的比例质量是解释多变量模型中基因组大小变化的最重要参数。因此，动力飞行的代谢强度似乎导致了鸟类基因组大小的减少。
