CAREER: Lung Ventilation in Lizards and the Evolution of Amniote Respiratory Mechanisms

拟议的职业规划整合了脊椎动物呼吸的解剖学和生理学研究，以及脊椎动物解剖学和比较生理学两门新的探究式课程的开发。 这些课程将脱离传统的讲课和考试的形式，大多数大学课程，而不是强调学生的研究相关的智力技能的发展。 拟议职业计划的研究部分侧重于脊椎动物呼吸机制（肺通气）的演变。 PI目前对肺通气演变的理解是完全不够的。 PI知道原始条件是使用口泵（颊泵）在正压下将空气压入肺部（如青蛙和肺鱼），而衍生条件（如爬行动物，鸟类和哺乳动物）是旋转肋骨并将空气吸入肺部（吸气呼吸）。 然而，PI目前几乎没有关于如何或为什么发生这种从口腔泵吸到吸入呼吸的戏剧性转变的信息。 生理特征，如呼吸机制，通常不能从化石骨骼中推断出来;因此，我们必须依靠表现出不同机制之间的中间状态的活体动物。 不幸的是，对于肺通气的研究，研究人员通常认为没有活着的动物表现出中间状态。 然而，PI最近发现，一些蜥蜴在运动时同时使用口腔泵和抽吸泵。 因此，蜥蜴的呼吸机制可能是介于纯颊泵和纯吸气呼吸之间的中间机制的“活化石”。 拟议的研究结合了广泛的蜥蜴物种的肺通气的全面解剖学和生理学研究，目的是使用这种活化石模型来了解脊椎动物中颊泵和吸入呼吸之间发生的戏剧性进化转变。

The proposed career plan integrates research on the anatomy and physiology of vertebrate respiration with the development of two new, inquiry-based courses in vertebrate anatomy and comparative physiology. These courses will depart from the traditional lecture-and-exam format of most college courses, and will instead emphasize the development of students' research-related intellectual skills. The research component of the proposed career plan focuses on the evolution of breathing mechanisms (lung ventilation) in vertebrate animals. The PIs current understanding of the evolution of lung ventilation is wholly inadequate. The PIs know that the primitive condition is to use a mouth pump (buccal pump) to force air into the lungs under positive pressure (as seen in frogs and lungfish) and that the derived condition (as seen in reptiles, birds and mammals) is to rotate the ribs and suck air down into the lungs (aspiration breathing). The PIs currently have little information, however, on how or why this dramatic transition from buccal pumping to aspiration breathing occurred. Physiological traits, such as breathing mechanisms, generally cannot be inferred from fossilized bones; therefore, we must rely on living animals that exhibit intermediate states between different mechanisms. Unfortunately for studies of lung ventilation, researchers have generally assumed that no living animals exhibit an intermediate state. The PIs have recently discovered, however, that some lizards utilize both a buccal pump and an aspiration pump during exercise. The breathing mechanism of lizards may therefore be a "living fossil" of an intermediate mechanism between pure buccal pumping and pure aspiration breathing. The proposed research incorporates comprehensive anatomical and physiological studies of lung ventilation in a wide range of lizard species, with the goal of using this living fossil model to understand the dramatic evolutionary transition that occurred between buccal pump and aspiration breathing in vertebrate animals.