Brain modularity across the theropod-bird transition: testing the influence of flight on neuroanatomical variation
Brain modularity across the theropod-bird transition: testing the influence of flight on neuroanatomical variation
复制标题
DOI：
10.1111/joa.12403
复制
发表时间：
2016-08-01
影响因子：
2.4
通讯作者：
Turner, Alan H.
中科院分区：
文献类型：
--
作者：
Balanoff, Amy M.;Smaers, Jeroen B.;Turner, Alan H.
现存的鸟类是唯一一个脑体积与身体大小之比接近哺乳动物所表现的独特的扩张值的脊椎动物。冠群鸟表现出的一系列复杂行为，包括社会性、声音学习、父母照顾和飞行，表明它们脑化的起源可能是由选择压力的马赛克驱动的。如果这是真的，大脑扩张的历史模式可能比早期对鸟类大脑的研究所提出的逐渐扩张或与飞行外观相关的突然扩张更为复杂。现代鸟类神经解剖学的起源被它们的系统发育干沿着超过1亿年的进化所掩盖（从中侏罗纪现代辐射的起源到从鳄系祖龙中分裂出来）。在这里，我们使用系统发育比较的方法来探索哪些进化的情况下最好地解释了现代鸟类和他们的非鸟类祖先的数字分区endocast测量体积的变化。我们的分析表明，在endocranium和cerebrum的相对体积的变化解释在这个谱系的结构变化。广义的多机制Ornstein-Uhlenbeck模型表明，动力飞行似乎不是观察到的变化的驱动因素，加强了鸟类大脑的深层历史是复杂的，细微差别仍有待发现的假设。
Living birds constitute the only vertebrate group whose brain volume relative to body size approaches the uniquely expanded values expressed by mammals. The broad suite of complex behaviors exhibited by crown-group birds, including sociality, vocal learning, parental care, and flying, suggests the origins of their encephalization was likely driven by a mosaic of selective pressures. If true, the historical pattern of brain expansion may be more complex than either a gradual expansion, as proposed by early studies of the avian brain, or a sudden expansion correlating with the appearance of flight. The origins of modern avian neuroanatomy are obscured by the more than 100 million years of evolution along their phylogenetic stem (from the origin of the modern radiation in the Middle Jurassic to the split from crocodile-line archosaurs). Here we use phylogenetic comparative approaches to explore which evolutionary scenarios best explain variation in measured volumes of digitally partitioned endocasts of modern birds and their non-avian ancestors. Our analyses suggest that variation in the relative volumes of the endocranium and cerebrum explain most of the structural variation in this lineage. Generalized multi-regime Ornstein-Uhlenbeck (OU) models suggest that powered flight does not appear to be a driver of observed variation, reinforcing the hypothesis that the deep history of the avian brain is complex, with nuances still to be discovered.