Fraser Danielle, Haupt Ryan J, Barr W Andrew
Palaeobiology Canadian Museum of Nature Ottawa ON Canada.
Department of Paleobiology Smithsonian Institution National Museum of Natural History Washington District of Columbia.
Ecol Evol. 2018 May 3;8(11):5355-5368. doi: 10.1002/ece3.4052. eCollection 2018 Jun.
In the absence of independent observational data, ecologists and paleoecologists use proxies for the Eltonian niches of species (i.e., the resource or dietary axes of the niche). Some dietary proxies exploit the fact that mammalian teeth experience wear during mastication, due to both tooth-on-tooth and food-on-tooth interactions. The distribution and types of wear detectible at micro- and macroscales are highly correlated with the resource preferences of individuals and, in turn, species. Because methods that quantify the distribution of tooth wear (i.e., analytical tooth wear methods) do so by direct observation of facets and marks on the teeth of individual animals, dietary inferences derived from them are thought to be independent of the clade to which individuals belong. However, an assumption of clade or phylogenetic independence when making species-level dietary inferences may be misleading if phylogenetic niche conservatism is widespread among mammals. Herein, we test for phylogenetic signal in data from numerous analytical tooth wear studies, incorporating macrowear (i.e., mesowear) and microwear (i.e., low-magnification microwear and dental microwear texture analysis). Using two measures of phylogenetic signal, heritability () and Pagel's λ, we find that analytical tooth wear data are not independent of phylogeny and failing to account for such nonindependence leads to overestimation of discriminability among species with different dietary preferences. We suggest that morphological traits inherited from ancestral clades (e.g., tooth shape) influence the ways in which the teeth wear during mastication and constrain the foods individuals of a species can effectively exploit. We do not suggest that tooth wear is simply phylogeny in disguise; the tooth wear of individuals and species likely varies within some range that is set by morphological constraints. We therefore recommend the use of phylogenetic comparative methods in studies of mammalian tooth wear, whenever possible.
在缺乏独立观测数据的情况下，生态学家和古生态学家使用物种的埃尔顿生态位（即生态位的资源或饮食轴）的替代指标。一些饮食替代指标利用了这样一个事实，即哺乳动物的牙齿在咀嚼过程中会因牙齿与牙齿以及食物与牙齿的相互作用而磨损。在微观和宏观尺度上可检测到的磨损分布和类型与个体进而与物种的资源偏好高度相关。由于量化牙齿磨损分布的方法（即分析牙齿磨损方法）是通过直接观察个体动物牙齿上的小平面和痕迹来进行的，因此从中得出的饮食推断被认为与个体所属的进化枝无关。然而，如果系统发育生态位保守性在哺乳动物中广泛存在，那么在进行物种水平的饮食推断时假设进化枝或系统发育独立性可能会产生误导。在此，我们在来自众多分析牙齿磨损研究的数据中测试系统发育信号，纳入宏观磨损（即中磨损）和微观磨损（即低倍微观磨损和牙齿微观磨损纹理分析）。使用系统发育信号的两种度量，遗传力（）和佩格尔的λ，我们发现分析牙齿磨损数据并非独立于系统发育，并且未能考虑这种非独立性会导致高估具有不同饮食偏好的物种之间的可区分性。我们认为从祖先进化枝继承的形态特征（例如牙齿形状）会影响牙齿在咀嚼过程中的磨损方式，并限制一个物种的个体能够有效利用的食物。我们并不是说牙齿磨损仅仅是伪装的系统发育；个体和物种的牙齿磨损可能在由形态限制设定的某个范围内变化。因此，我们建议在可能的情况下，在哺乳动物牙齿磨损研究中使用系统发育比较方法。
