Exploring the Roles of Competition and Constraint in the Evolution of Mammalian Behavior

目前，关于幼年哺乳动物的身体发育如何与幼崽环境中的社会和生态力量相互作用来影响其自身在重要生态任务中的表现，以及它的父母所表现出的行为，目前还知之甚少。这项研究将在食肉哺乳动物身上研究这种相互作用，这些哺乳动物食用坚硬的食物，如骨头。摄取坚硬食物的能力需要一个相对较大的头骨，能够承受否则可能导致头部和颌骨弯曲或断裂的力量。这项研究将检验一种假说，该假说认为，随着年轻的食肉动物成熟，这种异常健壮的头骨需要非常长的时间才能发育出来，这种缓慢的发育阻止了幼崽在幼年时比吃软食物的物种更好地发挥摄食能力，因此父母的补偿行为会随之演变，这样父母就可以帮助他们的幼崽进食，直到头骨更充分地形成。第二个假说将会得到检验，它表明头骨发育缓慢的影响会因青少年必须自己进食的社会环境而加剧。具体地说，当摄食竞争激烈时，父母可能会表现出极端的补偿性适应。通过结合野外和实验室研究，这些假说将通过对斑点鬣狗和条纹鬣狗这两个碎骨物种的头骨发育、摄食性能、摄食竞争和父母行为的比较分析来验证。斑点鬣狗是群居的，它们的觅食竞争很激烈，但条纹鬣狗是孤独的。这两只鬣狗在形态和表现上的发育模式将与其他几种不适合压碎骨头的食肉动物进行比较。这项工作将为形态发育和行为之间的进化关系提供大量信息。这项研究还将产生许多关于条纹鬣狗生物学的新信息，条纹鬣狗是目前人们知之甚少的为数不多的大型食肉动物之一。因此，这项研究将填补食肉动物生物学方面的一个重大空白，并为这些动物的保护提供关键信息。此外，这项研究将继续培训美国和肯尼亚的研究生，每年教授一门关于非洲哺乳动物行为生态学的海外留学课程，并为美国本科生提供在行为和形态之间的界面获得研究经验的独特机会。该奖项由国际科学和工程办公室共同资助

Little is currently known about how the physical development of a young mammal interacts with social and ecological forces at work in the youngsters environment to affect, not only its own performance in ecologically important tasks, but also the behavior exhibited by its parents. This research will investigate this interaction in carnivorous mammals that consume hard foods like bones. The ability to ingest hard foods requires a relatively massive skull that can withstand forces that might otherwise lead to bending or breakage of the bones of the head and jaws. The research will test an hypothesis suggesting that this type of unusually robust skull takes an exceptionally long time to develop as young carnivores mature, that this slow development prevents youngsters from optimizing feeding performance at a young age compared to species that eat softer foods, and that compensatory parental behavior evolves as a consequence so parents can help their young feed until the skull is more fully formed. A second hypothesis that will be tested suggests that the effects of slow skull development are exacerbated by the social environment in which the youngster must feed itself. Specifically, when feeding competition is intense, extreme compensatory adaptations may be expressed in parents. By combining field and laboratory studies, these hypotheses will be tested with a comparative analysis of skull development, feeding performance, feeding competition, and parental behavior in two bone-crushing species, the spotted hyena and the striped hyena. Spotted hyenas are gregarious and their feeding competition is intense, but striped hyenas are solitary. The patterns of development in morphology and performance will be compared in these two hyenas with those in several other carnivores that are not adapted for crushing bones. This work will provide a great deal of information about the evolutionary relationship between morphological development and behavior. The study will also generate much new information about the biology of the striped hyena, one of the few large carnivores about which very little is currently known. The study will thus fill a major gap in carnivore biology, and provide critical information for the conservation of these animals. Furthermore, this research will continue to train American and Kenyan graduate students, teach a study abroad course each year on the behavioral ecology of African mammals, and offer U.S. undergraduates unique opportunities to gain research experience at the interface between behavior and morphology.This award is co-funded by the Office of International Science and Engineering