Functional Tradeoffs in Specialization for Locomotion Versus Fighting

快速、经济的奔跑和战斗在大多数或所有陆生物种的生活史中都很重要。然而，允许快速、经济奔跑的肌肉骨骼“设计”可能与适合战斗的肌肉骨骼设计不相容。这种运动与战斗的权衡可能解释了许多近亲物种之间身体形态差异的情况，也可能有助于解释为什么同一物种的雄性和雌性在肌肉骨骼系统的大小和比例上经常不同。本研究将使用比较方法来检验快速、经济跑步专业化与战斗专业化之间功能权衡的假设。调查的第一个目的是测试两种哺乳动物目骨骼系统功能设计的广泛假设：偶蹄目（如鹿和羚羊）和食肉目（如狼和狮子）。利用博物馆的藏品，将测量大量物种的肢体骨骼比例，并与雄性侵略（大小两性二态性）和最大奔跑速度进行比较。该研究的第二个和第三个目的是量化两种表现出高度雄性竞争的物种（黑熊和野牛）和两种高度狡猾的物种（狼和叉角羚）在肢体骨骼和肌肉结构特性上的性别差异。因此，这项研究将检验肌肉骨骼在跑步和战斗方面的功能权衡的假设，并将大大扩展我们对哺乳动物肌肉骨骼系统性别二态性的认识和理解。该研究还将为6至9名本科生提供研究机会。我们还将创建一个开放访问的在线库，其中包含所有受试者的全肢骨解剖排列横截面的高分辨率CT扫描。最后，尽管大众对两性二态性知之甚少，但它对生理学、进化生物学以及人类进化和行为具有广泛的重要性。我们希望这里提出的研究能引起普遍的兴趣，并提供机会教育公众关于两性异形的生物学意义。

Both rapid, economical running and fighting are important in the life histories of most or all terrestrial species. Nevertheless, musculoskeletal "design" that allows rapid, economical running is likely to be incompatible with musculoskeletal design that is appropriate for fighting. This locomotor versus fighting tradeoff may explain many cases of divergence in body form among closely related species and may also help explain why males and females of the same species often differ in the size and proportions of their musculoskeletal system. This study will use comparative methods to test hypotheses of functional tradeoff between specialization for rapid, economical running versus specialization for fighting. The first aim of the investigation is to test a broad set of hypotheses of functional design of the skeletal system in two mammalian orders: Artiodactyla (e.g., deer and antelope) and Carnivora (e.g. wolves and lions). Using museum collections, limb bone proportions will be measured in a large number of species and compared with proxies for male-male aggression (size sexual dimorphism) and maximum running speed. The second and third aims of the study are to quantify sexual differences in the properties of limb bones and muscle architecture in 2 species exhibiting high levels of male-male competition (black bears and bisons) and 2 highly cursorial species (wolves and pronghorns). Hence, this investigation will test hypotheses of functional tradeoff between musculoskeletal specializations for running versus fighting and it will significantly expand our knowledge and understanding of the sexual dimorphism of the mammalian musculoskeletal system. The study will also provide research opportunities for 6 to 9 undergraduate students. We will also create an open access, online library of high resolution CT scans of anatomically aligned cross-sections of the whole limb bones from all of the subjects. Finally, although sexual dimorphism is poorly understood by the general public, it is of broad importance to physiology, evolutionary biology, and human evolution and behavior. We expect the research proposed here to be of general interest and to provide opportunities to educate the public about the biological significance of sexual dimorphism.