Morphological evolution and modularity of the caecilian skull
Morphological evolution and modularity of the caecilian skull
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DOI：
10.1186/s12862-018-1342-7
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发表时间：
2019-01-22
影响因子：
3.4
通讯作者：
Goswami, Anjali
中科院分区：
文献类型：
--
作者：
Bardua, Carla;Wilkinson, Mark;Goswami, Anjali
裸腹目（Gymnophiona）是现存种类最少的lissampibian目，但生活形式捕获了大约2.5亿年的进化，因为他们最早的分歧。这一悠久的历史反映在这个主要是掘土性但发育多样化的分支所表现出的广泛的头骨形态上。然而，这种形式的多样性使得定量的盲肠颅形态具有挑战性，具有高度可变的存在或不存在许多结构。因此，很少有研究探讨了整个无尾目的形态进化。这种广泛的变化也提出了这个分支内的颅模块（高度集成的特征的半自主子集）的保护程度的问题，使我们能够评估模块化组织在塑造形态进化的重要性。我们使用了密集的表面几何形态测量方法来量化所有32个现存的无尾目属的颅骨形态变化。我们用53个界标、687个曲线半界标和729个表面滑动半界标定义了16个颅区。有了这些前所未有的高维数据，我们分析了头骨的形状和模块化整个无尾目评估系统发育，异速生长和生态的影响，对颅骨的进化，以及调查之间的关系整合，进化速度和形态dispartial.ResultsWe发现最高的支持10模块模型，更大的整合后颅。系统发育信号是显著的（K-mult=0.87，p< 0.01），但在前模块中更强，而异速生长影响也是显著的（R-2=0.16，p< 0.01），但在后模块中更强。在系统发育分析后，生殖策略和化石定位程度对颅骨形态有显著影响（R-2=0.03-0.05），但影响较小（p
BackgroundCaecilians (Gymnophiona) are the least speciose extant lissamphibian order, yet living forms capture approximately 250 million years of evolution since their earliest divergences. This long history is reflected in the broad range of skull morphologies exhibited by this largely fossorial, but developmentally diverse, clade. However, this diversity of form makes quantification of caecilian cranial morphology challenging, with highly variable presence or absence of many structures. Consequently, few studies have examined morphological evolution across caecilians. This extensive variation also raises the question of degree of conservation of cranial modules (semi-autonomous subsets of highly-integrated traits) within this clade, allowing us to assess the importance of modular organisation in shaping morphological evolution. We used an intensive surface geometric morphometric approach to quantify cranial morphological variation across all 32 extant caecilian genera. We defined 16 cranial regions using 53 landmarks and 687 curve and 729 surface sliding semilandmarks. With these unprecedented high-dimensional data, we analysed cranial shape and modularity across caecilians assessing phylogenetic, allometric and ecological influences on cranial evolution, as well as investigating the relationships among integration, evolutionary rate, and morphological disparity.ResultsWe found highest support for a ten-module model, with greater integration of the posterior skull. Phylogenetic signal was significant (K-mult=0.87, p< 0.01), but stronger in anterior modules, while allometric influences were also significant (R-2=0.16, p< 0.01), but stronger posteriorly. Reproductive strategy and degree of fossoriality were small but significant influences on cranial morphology (R-2=0.03-0.05), after phylogenetic (p