Ontogenetic Scaling of Theoretical Bite Force in Southern Sea Otters (Enhydra lutris nereis)
Ontogenetic Scaling of Theoretical Bite Force in Southern Sea Otters (Enhydra lutris nereis)
复制标题
南方海獭 (EnHydra lutris nereis) 理论咬合力的个体发育尺度
DOI：
10.1086/688313
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发表时间：
2016
影响因子：
1.6
通讯作者：
R. Mehta
中科院分区：
文献类型：
--
作者：
Chris J. Law;Colleen Young;R. Mehta
由于生态位分歧的性别二型性往往与性别之间的差异，在饮食资源和字符相关的喂养和资源采购。虽然最近的研究表明，南方海獭（Enhydra lutris nereis）表现出不同的饮食偏好，以及性别的头骨大小和形状的二型性，这些性别间的差异是否转化为性别之间的喂养性能的分化仍有待研究。为了验证这一假设，缩放模式的咬合力，摄食性能的度量，不同的性别，我们计算了理论咬合力为55自然死亡的男性和女性南部海獭跨越个体发育遇到的大小范围。然后，我们使用标准化的主轴回归，同时确定的缩放模式的理论咬合力和头骨组件的个体发育，并评估这些缩放模式之间的性别差异。我们发现，正异速生长的理论咬合力的增加，正异速生长的增加，在生理横截面积的主要下巴收肌和机械优势。更仔细的检查显示，颞肌质量的异速生长增加和出杠杆长度的相对异速生长减少正在驱动这些模式。在我们的两性异形分析中，我们发现理论咬合力和形态特征的缩放模式在两性之间没有差异。然而，成年海獭的绝对咬合力不同，揭示成年男性表现出更大的咬合力，由于其较大的尺寸。我们发现两性之间的差异，咬的能力，提供了一些支持的生态位分歧假说。在这一领域的持续工作可能会链接到觅食功能形态与觅食生态学的两性差异，以显示生态位分歧有可能加强南部海獭的性二型性。
Sexual dimorphism attributed to niche divergence is often linked to differentiation between the sexes in both dietary resources and characters related to feeding and resource procurement. Although recent studies have indicated that southern sea otters (Enhydra lutris nereis) exhibit differences in dietary preferences as well as sexual dimorphism in skull size and shape, whether these intersexual differences translate to differentiation in feeding performances between the sexes remains to be investigated. To test the hypothesis that scaling patterns of bite force, a metric of feeding performance, differ between the sexes, we calculated theoretical bite forces for 55 naturally deceased male and female southern sea otters spanning the size ranges encountered over ontogeny. We then used standardized major axis regressions to simultaneously determine the scaling patterns of theoretical bite forces and skull components across ontogeny and assess whether these scaling patterns differed between the sexes. We found that positive allometric increases in theoretical bite force resulted from positive allometric increases in physiological cross-sectional area for the major jaw adductor muscle and mechanical advantage. Closer examination revealed that allometric increases in temporalis muscle mass and relative allometric decreases in out-lever lengths are driving these patterns. In our analysis of sexual dimorphism, we found that scaling patterns of theoretical bite force and morphological traits do not differ between the sexes. However, adult sea otters differed in their absolute bite forces, revealing that adult males exhibited greater bite forces as a result of their larger sizes. We found intersexual differences in biting ability that provide some support for the niche divergence hypothesis. Continued work in this field may link intersexual differences in feeding functional morphology with foraging ecology to show how niche divergence has the potential to reinforce sexual dimorphism in southern sea otters.