Taylor A B
Graduate School of Physical Therapy, Slippery Rock University, Pennsylvania, USA.
Am J Primatol. 1997;43(1):1-31. doi: 10.1002/(SICI)1098-2345(1997)43:1<1::AID-AJP1>3.0.CO;2-0.
Gorillas are the largest and among the most sexually dimorphic of all extant primates. While gorillas have been incorporated in broad-level comparisons among large-bodied hominoids or in studies of the African apes, comparisons between gorilla subspecies have been rare. During the past decade, however, behavioral, morphological, and molecular data from a number of studies have indicated that the western lowland (Gorilla gorilla gorilla) and eastern mountain (Gorilla gorilla beringei) subspecies differ to a greater extent than has been previously believed. In this study I compare patterns of relative growth of the postcranial skeleton to evaluate whether differences between subspecies result from the differential extension of common patterns of relative growth. In addition, patterns of ontogeny and sexual dimorphism are also examined. Linear skeletal dimensions and skeletal weight were obtained for ontogenetic series of male and female G.g. gorilla (n = 315) and G.g. beringei (n = 38). Bivariate and multivariate methods of analysis were used to test for differences in patterns of relative growth, ontogeny, and sexual dimorphism between sexes of each subspecies and in same-sex comparisons between subspecies. Results indicate males and females of both subspecies are ontogenetically scaled for postcranial proportions and that females undergo an earlier skeletal growth spurt compared to males. However, results also indicate that the onset of the female growth spurt occurs at different dental stages in lowland and mountain gorillas and that mountain gorillas may be characterized by higher rates of growth. Finally, data demonstrate lowland and mountain gorilla females do not differ significantly in adult body size, but mountain gorilla males are significantly larger than lowland gorilla males, suggesting mountain gorillas are characterized by a higher degree of sexual dimorphism in body size. Thus, although lowland and mountain gorillas do not appear to have evolved novel adaptations of the postcranium which correlate with differences in locomotor behavior, the present investigation establishes subspecies differences in ontogeny and sexual dimorphism which may be linked with ecological variation. Specifically, these findings are evaluated in the context of risk aversion models which predict higher growth rates and increased levels of sexual dimorphism in extreme folivores.
大猩猩是现存所有灵长类动物中体型最大且两性异形最为显著的物种之一。虽然大猩猩已被纳入大型类人猿的广泛比较研究中，或用于非洲猿类的研究，但大猩猩亚种之间的比较却很少见。然而，在过去十年中，多项研究的行为、形态和分子数据表明，西部低地大猩猩（Gorilla gorilla gorilla）和东部山地大猩猩（Gorilla gorilla beringei）亚种之间的差异程度比之前认为的更大。在本研究中，我比较了颅后骨骼的相对生长模式，以评估亚种之间的差异是否源于相对生长共同模式的差异扩展。此外，还研究了个体发育模式和两性异形。获取了G.g. gorilla（n = 315）和G.g. beringei（n = 38）成年雄性和雌性个体发育系列的线性骨骼尺寸和骨骼重量。采用双变量和多变量分析方法，测试每个亚种两性之间相对生长、个体发育和两性异形模式的差异，以及亚种间同性比较的差异。结果表明，两个亚种的雄性和雌性在颅后比例上均按个体发育进行缩放，且雌性比雄性经历更早的骨骼生长突增。然而，结果还表明，雌性生长突增的开始在低地和山地大猩猩的不同牙齿阶段出现，并且山地大猩猩可能具有更高的生长速率。最后，数据表明低地和山地大猩猩雌性在成年体型上没有显著差异，但山地大猩猩雄性明显大于低地大猩猩雄性，这表明山地大猩猩在体型上具有更高程度的两性异形。因此，尽管低地和山地大猩猩似乎没有进化出与运动行为差异相关的颅后新适应性，但本研究确定了个体发育和两性异形方面的亚种差异，这些差异可能与生态变异有关。具体而言，这些发现是在风险规避模型的背景下进行评估的，该模型预测极端食叶动物具有更高的生长速率和更高水平的两性异形。
