Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.
Evolution. 2013 Jan;67(1):241-59. doi: 10.1111/j.1558-5646.2012.01757.x. Epub 2012 Sep 7.
The study of modularity can provide a foundation for integrating development into studies of phenotypic evolution. The dentition is an ideal phenotype for this as it is developmentally relatively simple, adaptively highly significant, and evolutionarily tractable through the fossil record. Here, we use phenotypic variation in the dentition to test a hypothesis about genetic modularity. Quantitative genetic analysis of size variation in the baboon dentition indicates a genetic modular framework corresponding to tooth type categories. We analyzed covariation within the dentitions of six species of Old World monkeys (OWMs) to assess the macroevolutionary extent of this framework: first by estimating variance-covariance matrices of linear tooth size, and second by performing a geometric morphometric (GM) analysis of tooth row shape. For both size and shape, we observe across OWMs a framework of anterior and postcanine modules, as well as submodularity between the molars and premolars. Our results of modularity by tooth type suggest that adult variation in the OWM dentition is influenced by early developmental processes such as odontogenesis and jaw patterning. This study presents a comparison of genotypic modules to phenotypic modules, which can be used to better understand their action across evolutionary time scales.
模块性研究可以为将发育整合到表型进化研究中提供基础。牙齿是一个理想的表型，因为它在发育上相对简单，在适应上非常重要，并且可以通过化石记录来追踪进化。在这里，我们利用牙齿的表型变异来检验一个关于遗传模块性的假设。狒狒牙齿大小变化的数量遗传分析表明，牙齿类型类别对应于遗传模块框架。我们分析了六种旧世界猴子（OWM）的牙齿内变异性，以评估该框架的宏观进化程度：首先通过估计线性牙齿大小的方差协方差矩阵，其次通过进行牙齿排列形状的几何形态测量（GM）分析。对于大小和形状，我们在 OWM 中观察到前牙和后牙模块的框架，以及臼齿和前臼齿之间的亚模块性。我们通过牙齿类型的模块性结果表明，OWM 牙齿的成年变异受牙发生和颌模式等早期发育过程的影响。这项研究比较了基因型模块和表型模块，可以用来更好地理解它们在进化时间尺度上的作用。
