Evolution of jaw disparity in fishes
Evolution of jaw disparity in fishes
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DOI：
10.1111/pala.12371
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发表时间：
2018-11-01
期刊：
影响因子：
2.6
通讯作者：
Donoghue, Philip C. J.
中科院分区：
文献类型：
--
作者：
Hill, Jennifer J.;Puttick, Mark N.;Donoghue, Philip C. J.
脊椎动物下颌的形态已被用来推断摄食生态，下颌形状和结构的转变可能促进了脊椎动物进化中不同摄食行为的出现。在这里，我们提出了椭圆傅里叶形状和主成分分析，描述和比较了早期颚类动物和现代原始水生动物下颌形状的差异。 83% 的形状变异集中在前三个主成分轴上，早期颌口动物的所有成分进化枝都表现出重叠的形态变异。非四足形古生代肉鳍鱼比现存的同类更加不同，而现存的软骨鱼则比古生代的同类更加不同。更一般地说，现存的有颌鱼类比它们的古生代亲戚更加不同，这主要是因为现存放线鱼的下颌骨表现出广泛的形状变化。只有古生代有颚动物腾出的一些形状空间区域被活体类群汇聚重新填充。理论颌形态的表征表明，构成我们经验数据集的有颌鱼类实现的所有可能形状中不到一半；其中许多形态是由未代表性的陆地四足动物实现的，这意味着环境限制。我们的结果与分支进化的早期爆发模型不相容，并且与有颌鱼类进化史早期达到最大差异的假设相矛盾。
The morphology of the vertebrate lower jaw has been used to infer feeding ecology, with transformations in mandibular shape and structure likely to have facilitated the emergence of different feeding behaviours in vertebrate evolution. Here we present elliptical Fourier shape and principal component analyses, characterizing and comparing the disparity of jaw shape in early gnathostomes and their modern primitively aquatic counterparts. 83% of shape variation is summarized on the first three principal component axes and all component clades of early gnathostomes exhibit overlapping morphological variation. Non-tetrapodomorph Palaeozoic sarcopterygians are more disparate than their extant counterparts whereas extant chondrichthyans are more disparate than their Palaeozoic counterparts. More generally, extant jawed fishes are more disparate than their Palaeozoic relatives largely because of the extensive shape variation exhibited by mandibles of extant actinopterygians. Only some areas of shape space vacated by Palaeozoic gnathostomes have been convergently refilled by living taxa. Characterization of theoretical jaw morphologies demonstrates that fewer than half of all possible shapes are realized by the jawed fishes that comprise our empirical dataset; many of these morphologies are realized by unrepresented terrestrial tetrapods, implying environmental constraint. Our results are incompatible with the early burst model of clade evolution and contradict the hypothesis that maximum disparity is reached early in the evolutionary history of jawed fishes.