Kirk E Christopher
Department of Anthropology, University of Texas at Austin, 1 University Station C3200, 78712, USA.
J Hum Evol. 2006 Aug;51(2):159-70. doi: 10.1016/j.jhevol.2006.02.004. Epub 2006 Feb 28.
Among primates, nocturnal species exhibit relatively larger orbital apertures than diurnal species. Most researchers have considered this disparity in orbital aperture size to reflect differences in eye size, with nocturnal primates having relatively large eyes in order to maximize visual sensitivity. Presumed changes in eye size due to shifts in activity pattern are an integral part of theoretical explanations for many derived features of anthropoids, including highly convergent orbits and a postorbital septum. Here I show that despite clear differences in relative orbital aperture size, many diurnal and nocturnal primates do not differ in relative eye size. Among nocturnal primates, relative eye size is influenced by diet. Nocturnal visual predators (e.g., Tarsius, Loris, and Galago moholi) tend to have larger relative eye sizes than diurnal primates. By contrast, nocturnal frugivores (e.g., Perodicticus, Nycticebus, and Cheirogaleus) have relative eye sizes that are comparable to those of diurnal primates. Although some variation in orbital aperture size can be attributed to variation in eye size, both cornea size and orbit orientation also exert a strong influence on orbital aperture size. These findings argue for caution in the use of relative orbital aperture size as an indicator of activity pattern in fossil primates. These findings further suggest that existing scenarios for the evolution of unique orbital morphologies in anthropoids must be modified to reflect the importance of ecological variables other than activity pattern.
在灵长类动物中，夜行性物种的眼眶孔径相对比昼行性物种大。大多数研究人员认为眼眶孔径大小的这种差异反映了眼睛大小的差异，夜行性灵长类动物具有相对较大的眼睛，以便最大限度地提高视觉敏感度。由于活动模式的转变而假定的眼睛大小变化，是对类人猿许多衍生特征（包括高度汇聚的眼眶和眶后隔）进行理论解释的一个组成部分。在这里我表明，尽管相对眼眶孔径大小存在明显差异，但许多昼行性和夜行性灵长类动物的相对眼睛大小并无差异。在夜行性灵长类动物中，相对眼睛大小受饮食影响。夜行性视觉捕食者（如眼镜猴、懒猴和加纳夜猴）的相对眼睛大小往往比昼行性灵长类动物大。相比之下，夜行性食果动物（如树熊猴、蜂猴和鼠狐猴）的相对眼睛大小与昼行性灵长类动物相当。虽然眼眶孔径大小的一些变化可归因于眼睛大小的变化，但角膜大小和眼眶方向对眼眶孔径大小也有很大影响。这些发现表明，在将相对眼眶孔径大小用作化石灵长类动物活动模式指标时应谨慎。这些发现进一步表明，现有的关于类人猿独特眼眶形态进化的设想必须加以修改，以反映除活动模式之外的生态变量的重要性。
