Collaborative Resarch: Cetacean Phylogeny: A Reconciliation of Fossil and Neontological Data and the Importance of Taxonomic Sampling

9903964奥利里生物学家假设，鲸目动物（鲸鱼）是在多达6000万年前或更久以前从陆地陆地哺乳动物进化而来的。 这种进化转变是已知的最显著的转变之一，因为它涉及大小和形状的巨大变化。 如果我们能够理解这种进化转变，它就可以作为一个模型问题来描述进化新奇事物是如何出现的。 像陆行鲸这样的化石是鲸鱼曾经有腿并在陆地上行走的极好证据。 然而，在它们漫长的进化历史中，鲸鱼失去了后肢和毛发，发展出专门的头骨来在水下进食和听觉，在某些情况下，相对于它们5000多万年前的祖先，鲸鱼的体型超过了最大的恐龙。 为了了解这种进化转变是如何发生的，为什么以及何时发生的细节，重要的是要为鲸鱼及其近亲建立一个经过充分证实的系统发育树（家族史）。 理想情况下，研究与鲸鱼密切相关的所有物种的解剖学和分子生物学将是有趣的。 这些包括现存和灭绝的群体：偶蹄目，或偶数趾的有蹄哺乳动物（骆驼，猪，反刍动物，河马和亲戚），奇蹄目，或奇数趾的有蹄哺乳动物（马，犀牛，貘和亲戚），以及Procreodi，Condylarthra和Mesonychia，完全灭绝的有蹄哺乳动物群体。 特别是在灭绝的群体中，中甲可能与鲸目动物非常密切相关。大多数的分类群（90%），使上述组的利益是灭绝。 因此，试图为鲸鱼生成系统发育树的科学家被迫只使用部分数据，无论他们研究的是现存动物还是灭绝动物。 那些研究活动物的人（新生物学家）利用非常详细的生物特征（例如，所有生物体的解剖学、分子生物学、组织学等），但只在一个瞬间：现在。 那些研究灭绝物种的人（古生物学家）利用化石证据，这些证据几乎完全包括骨骼数据。 然而，这些数据可以用于更多物种，其中一些可能更接近最早鲸鱼的祖先状况。在这里，我们建议整合新生物学和古生物学的数据，以更好地检查鲸目动物的系统发育树。 这是至关重要的，因为科学家们在不同的数据类型上继续寻找不同的答案，以确定谁是鲸鱼的近亲：活的分类群表明它是鲸类，灭绝的分类群表明它是中爪类。 我们的目标是：1）增加灭绝和生活的鲸鱼及其亲属的分类和特征采样，2）研究某些生物属性（例如，分子、形态学）具有似乎与整个家谱不匹配的进化历史。 我们的目标是使我们的形态学工作的结果尽可能标准化与出版的插图。这个项目的数据收集方面是大的，我们将利用这一机会，指导高中和本科生谁可能有兴趣在进化和系统学的研究，谁可以教实验室，计算机和数据分析技能，以及进化理论。

9903964O'Leary Biologists hypothesize that cetaceans (whales) evolved from terrestrial land mammals as many as 60 million years ago or more. This evolutionary transformation is one of the most remarkable known because it involved dramatic changes in size and shape. If we can understand this evolutionary transition it may serve as a model problem describing how evolutionary novelties appear. Fossils, like Ambulocetus, are excellent evidence that whales once had legs and walked on land. During their long evolutionary history whales have, however, lost their hind limbs and hair, developed specialized skulls to feed and hear underwater, and in some cases exceeded the largest dinosaur in body size relative to their ancestors of over 50 million years ago. In order to understand the details of how, why and when this evolutionary transformation occurred, it is important to develop a well-corroborated phylogenetic tree (family history) for whales and their close relatives. Ideally it would be of interest to study the anatomy and molecular biology of all species that are closely related to whales. These include living and extinct groups: Artiodactyla, or even-toed hoofed mammals (camels, pigs, ruminants, hippopotamids and relatives), Perissodactyla, or odd-toed hoofed mammals (horses, rhinos, tapirs and relatives), as well as Procreodi, Condylarthra and Mesonychia, completely extinct groups of hoofed mammals. In particular among the extinct groups, Mesonychia may be very closely related to cetaceans. Most of the taxa ( 90%) that make up the group of interest outlined above are extinct. As a result, scientists trying to generate a phylogenetic tree for whales are forced to work with only part of the data whether they study living animals or extinct animals. Those working on living animals (neontologists) draw on very detailed biological characters (e.g., all of the organisms' anatomy, molecular biology, histology, etc) but only in one instant of time: the present. Those working on extinct species (paleontologists) draw on fossil evidence which almost exclusively comprises skeletal data. However, these data can be scored for many more species, some of which may more closely approximate the ancestral condition of the earliest whales. Here we propose to integrate neontological and paleontological data, to better examine the phylogenetic tree of cetaceans. This is critical to do at this time because scientists working on different data types continue to find different answers as to who is the closest relative of whales: living taxa indicate that it is the hippopotamus and extinct taxa indicate that it is mesonychians. We aim 1) to increase the taxon and character sampling for both extinct and living whales and relatives, and 2) to examine how and why certain biological attributes (e.g., molecules, morphology) have evolutionary histories that do not appear to match the overall family tree. We aim to make the results of our morphological work as standardized as possible with published illustrations. The data collection aspect of this project is large and we will use this as an opportunity to mentor high school and undergraduate students who may be interested in research in evolution and systematics and who can be taught laboratory, computer, and data analysis skills as well as evolutionary theory.