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A general framework for inferring the developmental causes of modularity of morphological variation with applications to the craniomandibular complex in rodents.

机译：推断形态变异模块化发展原因的通用框架，并应用于啮齿动物的颅下颌复合体。

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摘要

Modularity is a principle of construction whereby individual units are internally cohesive and relatively autonomous from other such units. Modularity thus confers a degree of evolutionary autonomy to the sets of traits integrating a module, a feature hypothesized to enhance evolvability by allowing selection to optimize individual parts without interfering with others. Detecting modularity in morphological traits requires analyzing the structure of covariation because traits integrated by development into modules are expected to show stronger mutual covariation. However, unambiguous patterns of modularity are rare. That is because the developmental processes underlying most phenotypic traits share regulatory elements and/or have spatially overlapping effects. Pervasive interactions can produce the appearance of statistical integration among biologically modular traits. Herein, a statistical framework is provided that confronts these limitations on methods for inferring modularity from morphological data. The theoretical basis of this new method states that modules are subsets of dimensions embedded in phenotypic space, an approach that differs from previous ones by not defining modules as anatomical parts but rather as aspects of the variation of these parts. This abstraction allows traits to be integrated into more than one module and also suggests a natural approach for testing a priori hypotheses of modularity by fitting competing hypotheses to observed covariance matrices, searching for the best-supported causal explanations. A comprehensive method is developed and tested using simulated data, then used to address a major outstanding issue in evolutionary biology: whether the developmental processes that structure variation within populations bias the direction of long-term divergence. This hypothesis is tested by fitting multiple developmental models to both intraspecific and interspecific craniomandibular data obtained from a clade of ecologically diverse rodents. Results reveal a remarkable congruence among patterns within and between species, and they also suggest that there are different mechanisms by which modular variation arises within different parts of the skull, i.e., cranium and mandible. That these structures have different dynamics both within and among species suggests that whether intraspecific variation constrains the direction of divergence may depend on mechanisms structuring modularity within populations.
机译：模块化是一种构造原理，其中各个单元在内部具有内聚性，并且相对于其他此类单元而言相对自治。因此，模块化赋予了集成模块的特性集一定程度的进化自主权，该特性被认为可以通过允许选择来优化单个部件而不会干扰其他部件来增强可进化性。检测形态特征的模块性需要分析协变的结构，因为通过开发整合到模块中的特征有望表现出更强的相互协变。但是，很少有明确的模块化模式。这是因为，大多数表型性状的发育过程共享调控元件和/或具有空间重叠效应。普遍的相互作用可以在生物模块性状之间产生统计整合的外观。在此，提供了一种统计框架，该框架在从形态学数据推断模块性的方法上面临这些限制。这种新方法的理论基础指出，模块是表型空间中嵌入的维的子集，这种方法与以前的方法不同，它没有将模块定义为解剖部分，而是将这些部分定义为变化的方面。这种抽象可以将特征整合到一个以上的模块中，并且还提出了一种自然的方法，可以通过将竞争性假设与观察到的协方差矩阵拟合，以寻找得到最佳支持的因果解释，从而测试模块化的先验假设。开发了一种综合方法，并使用模拟数据进行了测试，然后用于解决进化生物学中的一个主要悬而未决的问题：种群内部结构变化的发育过程是否偏向了长期差异的方向。通过将多种发育模型拟合到从生态多样的啮齿类动物进化枝中获得的种内和种间颅颌下颌骨数据，来检验该假设。结果揭示了物种内部和物种之间的模式之间的显着一致性，并且它们还表明，在颅骨的不同部分（即颅骨和下颌骨）内出现模块化变化的机制不同。这些结构在物种内部和物种之间具有不同的动力学，这表明种内变异是否限制了发散的方向，可能取决于构建种群内部模块性的机制。

著录项

  • 作者

    Marquez, Eladio J.;

  • 作者单位

    University of Michigan.;

  • 授予单位 University of Michigan.;
  • 学科 Biology Anatomy.;Biology Evolution and Development.;Biology Biostatistics.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 172 p.
  • 总页数 172
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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