Brain Evolution across the Puerto Rican Anole Radiation
Brain Evolution across the Puerto Rican Anole Radiation
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DOI：
10.1159/000341161
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发表时间：
2012-08
期刊：
影响因子：
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通讯作者：
B. Powell;M. Leal
中科院分区：
文献类型：
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作者：
B. Powell;M. Leal
大脑进化的模式在脊椎动物中得到了广泛的研究，大部分研究使用哺乳动物和/或鸟类作为模型系统。在这些群体中，占据不同栖息地的物种已被证明具有不同的神经解剖学，特别是关于不同大脑结构的相对大小的差异，与栖息地复杂性的差异相关。我们研究了异速生长缩放模式的端脑，背侧皮质，背内侧皮质，背侧脑室脊，髓质和小脑在6种波多黎各阿诺利斯蜥蜴，这是分组在三个不同的ecomorphs（即生态类型）根据种间差异的首选栖息地类型。栖息地偏好的差异伴随着形态和行为的适应，有效地利用每一种栖息地类型。我们的研究结果挑战了这一趋势，并证明了属于同一生态类型的物种之间不同大脑结构的相对大小缺乏收敛性。总脑体积解释了92.5%和99.8%之间的变异，在体积的每个大脑区域测量和93.8%和98.5%之间的变异，在体积的每个组件测量端脑。这种大脑异速生长的模式与协调的大脑进化是一致的。然而，在小脑的情况下，种间差异的体积表现出一种趋势，按照马赛克大脑的进化。这表明，协调的大脑进化和马赛克的大脑进化都塑造了变色龙的大脑，前者发挥了主导作用。协调一致的大脑进化是哺乳动物和软骨鱼类大脑形成的主要机制，它在阿诺利斯蜥蜴中的存在提供了额外的证据支持这一假设，即协调一致的大脑进化可能来自所有脊椎动物共同的大脑发育保守模式。更一般地说，我们的研究结果强调了进一步研究爬行动物大脑进化的必要性，因为它们可以为脊椎动物大脑进化的机制提供有价值的见解。
Patterns of brain evolution have been widely studied across vertebrates, with the bulk of studies using mammals and/or birds as model systems. Within these groups, species occupying different habitats have been shown to have divergent neuroanatomy, particularly with regard to differences in the relative size of different brain structures, correlated with differences in habitat complexity. We examined the pattern of allometric scaling across the telencephalon, dorsal cortex, dorsomedial cortex, medial cortex, dorsal ventricular ridge, medulla and cerebellum in six species of Puerto Rican Anolis lizards, which are grouped in three distinct ecomorphs (i.e. ecological types) according to interspecific differences in preferred habitat type. The differences in habitat preferences are accompanied by morphological and behavioral adaptations for effective use of each habitat type. Our results challenge this trend and demonstrate a lack of convergence in the relative size of different brain structures between species belonging to the same ecomorph type. Overall brain volume explained between 92.5 and 99.8% of the variance in the volume of each of the brain regions measured and 93.8 and 98.5% of the variance in the volume of each component measured within the telencephalon. This pattern of brain allometry is consistent with concerted brain evolution. However, in the case of the cerebellum, interspecific differences in volume exhibit a trend in accordance with mosaic brain evolution. This suggests that both concerted and mosaic brain evolution have shaped the anole brain, with the former playing a dominant role. Concerted brain evolution is the primary mechanism shaping the brain in mammals and cartilaginous fishes, and its presence in Anolis lizards provides additional evidence supporting the hypothesis that concerted brain evolution might result from a conserved pattern of brain development common to all vertebrates. More generally, our findings highlight the necessity of further studies of brain evolution in reptiles as they can provide valuable insights into the mechanisms underlying vertebrate brain evolution.