Functional Tradeoffs in Specialization for Locomotion Versus Fighting

在大多数或所有陆地物种的生活史上，快速、经济的奔跑和战斗都是重要的。然而，允许快速、经济的跑步的肌肉骨骼设计很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缘物种在身体形态上的差异，也可能有助于解释为什么同一物种的雄性和雌性的肌肉骨骼系统的大小和比例经常不同。这项研究将使用比较的方法来检验快速、经济运行的专门化和战斗的专门化之间的功能权衡假设。这项研究的第一个目的是在两个哺乳动物目：偶蹄目(例如鹿和羚羊)和食肉目(例如狼和狮子)中测试骨骼系统功能设计的一套广泛的假说。利用博物馆的收藏品，将测量大量物种的四肢骨骼比例，并与男性-男性攻击性(体型、性别二型性)和最大跑步速度的替代品进行比较。这项研究的第二和第三个目标是量化两种雄性竞争程度较高的物种(黑熊和比翁)和两种高度卷曲的物种(狼和叉角羚)在四肢骨骼和肌肉结构特性上的性别差异。因此，这项研究将检验奔跑和搏斗肌肉骨骼特化之间的功能权衡假设，并将极大地扩展我们对哺乳动物肌肉骨骼系统性别二型性的认识和理解。这项研究还将为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高分辨率CT扫描库，其中包含所有受试者的整个四肢骨骼的解剖定位横断面。最后，尽管大众对性二形现象知之甚少，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具有普遍的兴趣，并提供机会教育公众关于性二型性的生物学意义。

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.