Secondary adaptation to aquatic life: an integrative morphofunctional analysis in Cetartiodactyla

对水生生物的二次适应：鲸鱼的综合形态功能分析

• 批准号: 495352270
• 负责人: Dr. Eli Amson
• 金额: --
• 依托单位: Departement Histoire de la Terre, UMR 5143 du CNRS
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/495352270?language=en
• 关键词: Secondary; adaptation; aquatic; life; integrative

Lifestyle transitions are major evolutionary events often reflected by extreme morphological modifications. One particularly obvious example is the secondary adaptation of whales to an aquatic lifestyle. Toothed and baleen whales (Cetacea) are included in the Cetartiodactyla clade with even-toed ungulates (“Artiodactyla”). Their early fossil record documents species within the paraphyletic “Archaeoceti” that are crucial to understand this major evolutionary transition from the terrestrial to the aquatic environment. Members of the earliest known family, the Pakicetidae, were mostly terrestrial with some adaptations to water. They lived during the early Eocene (ca. 50 million years ago). And it is mostly during the middle to late Eocene that the quadrupedal whales “Protocetidae” diversified. They represent a key stage of cetacean locomotor evolution, displaying swimming abilities close to modern otters. This project will focus in particular on a new middle Eocene protocetid from Peru, with exceptionally well-preserved postcranial elements, Peregocetus pacificus. Its postcranial gross morphology and microanatomy will be thoroughly described – combining external morphology observation and measurements to computed tomography data – and compared with other extinct and extant mammals to interpret the function of key anatomical traits. Variables of importance for the land-to-water transition will be further studied with phylogenetic comparative methods. This will involve reconstructing the most likely ancestral states for these variables and mapping the evolution of these aquatic adaptations on the phylogeny of cetartiodactyls. We will identify the most likely evolutionary model that led extinct whales to an aquatic lifestyle by means of evolutionary model comparison. Finally, a multivariate dataset will be used in a phylogenetically informed discriminant analysis to reconstruct the locomotion mode of Peregocetus pacificus and other extinct cetaceans.

生活方式的转变是主要的进化事件，往往反映在极端形态的修改。一个特别明显的例子是鲸鱼对水生生活方式的二次适应。齿鲸和须鲸（鲸目）包括在鲸偶蹄目分支与偶数趾有蹄类动物（“偶蹄目”）。它们的早期化石记录记录了并系“古鲸”中的物种，这些物种对于理解从陆地环境到水生环境的这一重大进化转变至关重要。已知最早的家庭成员，Pakicetidae，大多是陆地与一些适应水。他们生活在始新世早期（约公元前200年）。5000万年前）。而四足鲸“Protocetidae”的多样化主要是在始新世中晚期。它们代表了鲸类运动进化的一个关键阶段，显示出接近现代水獭的游泳能力。该项目将特别侧重于一个新的中始新世protocetid从秘鲁，与保存异常完好的颅后元素，Peregocetus pacificus。它的颅后大体形态和显微解剖将被彻底描述-结合外部形态观察和测量计算机断层扫描数据-并与其他灭绝和现存的哺乳动物进行比较，以解释关键解剖特征的功能。陆地向水过渡的重要变量将进一步研究系统发育比较方法。这将涉及重建这些变量的最有可能的祖先状态，并绘制这些水生适应的演化对cetartiodactyls的进化。我们将通过进化模型的比较来确定最有可能导致灭绝的鲸鱼进入水生生活方式的进化模型。最后，一个多变量数据集将被用于一个基于遗传信息的判别分析，以重建太平洋Peregocetus pacificus和其他灭绝的鲸类动物的运动模式。