Collaborative Research: Feeding and Diet at the Origin of Whales: Evolution, Function, and Development

合作研究：鲸鱼起源的喂养和饮食：进化、功能和发育

• 批准号: 0745543
• 负责人: Johannes Thewissen
• 金额: $ 25.94万
• 依托单位: Northeast Ohio Medical University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-02-15 至 2013-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0745543&HistoricalAwards=false
• 关键词: Collaborative; Research; Feeding; Diet; Origin

Collaborative Research: Feeding and Diet at the Origin of Whales: Evolution, Function, and Development J. G. Thewissen and M. T. ClementzCetaceans (whales, porpoises, and dolphins) originated from land mammals (even-toed ungulates or Artiodactyla) about 50 million years ago. A remarkable series of fossils documents this transition and whale origins has become one of the most celebrated examples of macroevolutionary change in the fossil record. In spite of this, it is not known why whale ancestors took to the water. The objective of this project is to investigate whether diet and feeding played a critical role in the land-to-water, artiodactyl-to-whale transition.This project studies feeding and diet during the artiodactyl-to-whale transition using five approaches. First, the morphology of the molars gives clues to their use, are they used to shear, crush, or grind food. Those food processing methods correlate, in modern mammals, to specific diets, and can thus be used to infer diets in extinct animals. Second, the shape and design of skull and mandible of these early whales shows how the chewing muscles were attached, and clarifies hw the jaws were used in processing food, another feature that differs in animals that eat different food items. Third, dental wear facets show how teeth were used during chewing, and these wear facets are highly unusual in fossil whales, suggesting a very specialized diet. Fourth, since the molecules that make teeth are derived from an animal's diet, study of the chemistry of the teeth (stable isotopes) can answer questions about that diet. Lastly, a study of modern dolphin embryos will tell us how dolphin tooth germ form, and how they are derived from fossil whales. Together, using these five approaches to study feeding across the artiodactyls-whale transition will be used to answer a number of specific questions about the evolution of feeding and diet, such as whether a species is a suction feeder, whether fish dominated in its diet, or whether carnivore-like shearing occurred.Combined with data on the evolution of other organ systems in early whales, we will be able to study several questions: 1, Was diet an important reason why whales went into the water? 2, Was early cetacean evolution characterized by a period of experimentation with diets and feeding strategies or was a fish-diet acquired early in evolution?, 3, Does dental morphology and dental function change hand-in-hand across the artiodactyls-whale transition or are they temporally disjunct? These results integrate information at multiple organizational levels, from genes controlling development, to stable isotopes gauging life history parameters, and to muscle moments controlling jaw closing. This integrated approach is exciting because scientists with very different backgrounds all contribute pieces to the puzzle that allows for a thorough understanding of whale origins. The broader impact of the proposal is that whale origins is a topic of great interest to scientists, educators, and the public-at-large. This proposal includes an outreach program that makes its results accessible through the www. It also includes a detailed program that enriches the science curriculum of local, rural fourth and fifth graders in northeast Ohio. This proposal presents hands-on sessions that present whale research as a springboard to science and research and ties in directly to mandated curricular elements on geology, paleontology, anatomy, and embryology. After fine-tuning, these sessions will be adapted to be available for nationwide use.

鲸类动物（鲸、鼠海豚和海豚）起源于大约5000万年前的陆地哺乳动物（偶蹄目或偶蹄目）。一系列引人注目的化石记录了这种转变和鲸鱼的起源，成为化石记录中最著名的宏观进化变化的例子之一。尽管如此，人们还不知道鲸鱼的祖先为什么要下水。这个项目的目的是调查饮食和喂养是否在陆地到水，偶蹄动物到鲸鱼的转变中发挥了关键作用。本项目使用五种方法研究偶蹄类动物向鲸鱼过渡期间的喂养和饮食。首先，臼齿的形态为它们的用途提供了线索，它们是用来剪切、压碎还是研磨食物。在现代哺乳动物中，这些食物加工方法与特定的饮食有关，因此可以用来推断灭绝动物的饮食。其次，这些早期鲸鱼的头骨和下颌骨的形状和设计表明了咀嚼肌肉是如何附着的，并阐明了颌骨是如何用于加工食物的，这是吃不同食物的动物的另一个不同特征。第三，牙齿磨损面显示了牙齿在咀嚼过程中是如何使用的，这些磨损面在鲸鱼化石中非常罕见，表明它们的饮食非常特殊。第四，由于构成牙齿的分子来自动物的饮食，对牙齿的化学成分（稳定同位素）的研究可以回答有关饮食的问题。最后，对现代海豚胚胎的研究将告诉我们海豚牙胚是如何形成的，以及它们是如何从鲸鱼化石中衍生出来的。总之，使用这五种方法来研究偶蹄类动物从鲸鱼到哺乳动物的转变过程中的进食，将被用来回答一些关于进食和饮食进化的具体问题，比如一个物种是否是吸吮型进食动物，它的饮食中是否有鱼类占主导地位，或者是否发生了类似食肉动物的剪切。结合早期鲸鱼其他器官系统的进化数据，我们将能够研究几个问题：1、饮食是鲸鱼进入水里的重要原因吗？2、早期鲸类动物进化的特点是在一段时间内对饮食和喂养策略进行实验，还是在进化的早期就获得了以鱼为食的饮食？在偶蹄目动物向鲸鱼转变的过程中，牙齿的形态和功能是同步变化的，还是暂时分离的？这些结果整合了多个组织层面的信息，从控制发育的基因，到测量生活史参数的稳定同位素，再到控制下颌闭合的肌肉力矩。这种综合的方法是令人兴奋的，因为来自不同背景的科学家都为这个谜题贡献了自己的一份力量，让我们能够彻底了解鲸鱼的起源。该提案的广泛影响是，鲸鱼的起源是科学家、教育工作者和广大公众非常感兴趣的话题。该提案包括一个外联计划，使其结果可通过万维网访问。它还包括一个详细的计划，以丰富俄亥俄州东北部当地和农村四年级和五年级学生的科学课程。该提案提出了实践课程，将鲸鱼研究作为科学研究的跳板，并直接与地质学、古生物学、解剖学和胚胎学等必修课程联系起来。经过微调后，这些课程将在全国范围内使用。