The Evolutionary Continuum of Functional Homodonty to Heterodonty in the Dentition of Halichoeres Wrasses
The Evolutionary Continuum of Functional Homodonty to Heterodonty in the Dentition of Halichoeres Wrasses
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DOI：
10.1093/icb/icaa137
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发表时间：
2023-07-31
影响因子：
2.6
通讯作者：
Summers, Adam P.
中科院分区：
文献类型：
--
作者：
Cohen, Karly E.;Weller, Hannah I.;Summers, Adam P.
脊椎动物的牙齿通常被分解成几个离散的类别，掩盖了它们之间潜在的重要功能差异，也掩盖了对它们进化的洞察。同牙和异牙这两个术语通常将牙齿形态与牙齿功能混为一谈，并要求上下文相关的子类别具有任何特定的含义。限定词如初期、暂时性或系统发育同齿，试图提供一个更严格的定义，但却强调了对牙列进行分类的困难。为了解决这些问题，我们最近提出了一种量化牙齿电池功能的方法，该方法基于每个牙齿的估计应力(使用表面积推断)，并对颌骨外伸杠杆(使用牙齿位置推断)进行标准化。这种方法揭示了一个同齿-异牙的功能连续体，在这个连续体中，小牙齿和大牙齿一起工作，向猎物传递力量。形态同牙或异牙指的是形态，而功能同牙或异牙指的是应力的传递。在这项研究中，我们使用Halichoeres Wrass来探索如何通过从功能同齿-异牙连续体生成两个连续的度量来将功能连续体用于系统发育分析。在这里，我们展示了功能异齿牙齿至少进化了3次在哈利乔尔龙虾。上颌比下颌有更多的功能异牙牙，但下颌骨的功能异牙牙承受的应力明显更大。这些具有功能后果的细微差别，如果将整个牙列分成不同的类别，就会被忽略。这一分析指出了值得从机械和发育角度仔细观察的领域，即在不同的颌骨和不同的颌骨区域中出现的异牙的分布和类型。这些在一小群乌贼身上的数据表明，连续的牙齿变量可以丰富地洞察更广泛种类的鱼类摄食机制的进化。
Synopsis Vertebrate dentitions are often collapsed into a few discrete categories, obscuring both potentially important functional differences between them and insight into their evolution. The terms homodonty and heterodonty typically conflate tooth morphology with tooth function, and require context-dependent subcategories to take on any specific meaning. Qualifiers like incipient, transient, or phylogenetic homodonty attempt to provide a more rigorous definition but instead highlight the difficulties in categorizing dentitions. To address these issues, we recently proposed a method for quantifying the function of dental batteries based on the estimated stress of each tooth (inferred using surface area) standardized for jaw out-lever (inferred using tooth position). This method reveals a homodonty-heterodonty functional continuum where small and large teeth work together to transmit forces to a prey item. Morphological homodonty or heterodonty refers to morphology, whereas functional homodonty or heterodonty refers to transmission of stress. In this study, we use Halichoeres wrasses to explore how a functional continuum can be used in phylogenetic analyses by generating two continuous metrics from the functional homodonty-heterodonty continuum. Here we show that functionally heterodont teeth have evolved at least 3 times in Halichoeres wrasses. There are more functionally heterodont teeth on upper jaws than on lower jaws, but functionally heterodont teeth on the lower jaws bear significantly more stress. These nuances, which have functional consequences, would be missed by binning entire dentitions into discrete categories. This analysis points out areas worth taking a closer look at from a mechanical and developmental point of view with respect to the distribution and type of heterodonty seen in different jaws and different areas of jaws. These data, on a small group of wrasses, suggest continuous dental variables can be a rich source of insight into the evolution of fish feeding mechanisms across a wider variety of species.