Chivers D J, Hladik C M
J Morphol. 1980 Dec;166(3):337-86. doi: 10.1002/jmor.1051660306.
Three categories of dietary adaptation are recognized--faunivory, frugivory, and folivory--according to the distinctive structural and biochemical features of animal matter, fruit, and leaves respectively, and the predominance of only one in the diets of most species. Mammals subsisting mainly on animal matter have a simple stomach and colon and a long small intestine, whereas folivorous species have a complex stomach and/or an enlarged caecum and colon; mammals eating mostly fruit have an intermediate morphology, according to the nature of the fruit and their tendency to supplement this diet with either animal matter or leaves. The frugivorous group are mostly primates: 50 of the 78 mammalian species, and 117 of the 180 individuals included in this analysis are primates. Coefficients of gut differentiation, the ratio of stomach and large intestine to small intestine (by area, weight, and volume), are low in faunivores and high in folivores; the continuous spread of coefficients reflects the different degrees of adaptation to these two dietary extremes. Interspecific comparisons are developed by allowing for allometric factors. In faunivores, in which fermentation is minimal, the volume of stomach and large intestine is related to actual body size, whereas these chambers are more voluminous in larger frugivores and mid-gut fermenting folivores; fore-gut fermenters show a marked decrease in capacity with increasing body size. Surface areas for absorption are related to metabolic body size, directly so in frugivores; area for absorption is relatively less in larger faunivores and more in large folivores, especially those with large stomachs. Indices of gut specialization are derived from these regressions by nonlinear transformation, with references to the main functional features of capacity for fermentation and surface area for absorption. These are directly comparable with the dietary index, derived from quantitative feeding data displayed on a three-dimensional graph, with all species within a crescentic path from 100% faunivory through 55--80% frugivory to 100% folivory, perhaps illustrating, at least for primates, the evolutionary path from primitive insectivorous forms through three major ecological grades.
根据动物类食物、水果和树叶各自独特的结构和生化特征，以及大多数物种饮食中仅以其中一种为主的情况，可识别出三类饮食适应性——食虫性、食果性和食叶性。主要以动物类食物为生的哺乳动物有一个简单的胃和结肠以及一条长长的小肠，而食叶性物种有一个复杂的胃和/或一个扩大的盲肠和结肠；根据水果的性质以及它们用动物类食物或树叶补充这种饮食的倾向，以水果为主食的哺乳动物具有中间形态。食果性群体大多是灵长类动物：在此次分析涵盖的78种哺乳动物中，有50种是灵长类动物，在180个个体中有117个是灵长类动物。肠道分化系数，即胃和大肠与小肠的比例（按面积、重量和体积计算），在食虫动物中较低，在食叶动物中较高；系数的连续变化反映了对这两种极端饮食的不同适应程度。种间比较是通过考虑异速生长因素来进行的。在发酵作用最小的食虫动物中，胃和大肠的体积与实际体型相关，而在体型较大的食果动物和中肠发酵的食叶动物中，这些腔室的体积更大；前肠发酵动物的容量随着体型增大而显著减小。吸收面积与代谢体型相关，在食果动物中是直接相关；在体型较大的食虫动物中，吸收面积相对较小，在大型食叶动物中则较大，尤其是那些胃大的食叶动物。肠道特化指数是通过对这些回归进行非线性变换得出的，参考了发酵能力和吸收面积的主要功能特征。这些指数可直接与饮食指数进行比较，饮食指数是根据在三维图上显示的定量摄食数据得出的，所有物种都处于从100%食虫性到55 - 80%食果性再到100%食叶性的新月形路径内，这或许至少对灵长类动物而言，说明了从原始食虫形态经过三个主要生态等级的进化路径。
