Cruising the whale superhighway: The evolution, biomechanics, and ecological drivers of migration in cetaceans

鲸鱼是一种多样化的水生哺乳动物，在海洋群落中扮演着广泛的重要角色。它们表现出的一个令人惊讶的行为是，在每年的年度迁徙中，它们都能在世界各地长途跋涉。它们从食物丰富的极地地区迁徙到靠近热带的地区，在那里它们可以远离捕食者抚养后代。鲸鱼的长途迁徙在生态上是重要的，因为它们从极地所吃的食物中转移了大量的营养物质，然后通过排便或死亡将这些营养物质释放到繁殖区。例如，海底掉落的鲸鱼尸体为整个海洋生态系统提供了基础。虽然完全水生的鲸鱼在4000多万年前就进化出来了，但在它们漫长的进化史中，迁徙是从什么时候开始的还不清楚。据推测，全球气候变化，如极地冰盖的形成，可能为鲸鱼迁徙提供了环境动力，但人们对行为、生态和进化之间的联系知之甚少。这项研究将调查现代鲸鱼的长途迁徙，然后应用这些知识来理解古代鲸鱼的迁徙行为是如何以及何时进化的。我们的目标是研究使长途迁徙成为可能的形态学功能变化，以及驱动这些史诗般的旅程开始的环境因素。首先，我们将研究鲸鱼的体型是如何适应现代鲸鱼的长距离游泳的。我们会问：迁徙鲸鱼的生物力学是否适合长距离游泳？我们将通过测量鲸鱼的体型变化，并使用计算机模型来估计鲸鱼游泳的流体动力学来做到这一点。接下来，我们将研究鲸鱼迁徙背后的环境驱动因素，并预测它们在地球历史上何时出现。我们会问：鲸鱼繁殖和觅食地的环境条件有何不同？这些特殊的环境是什么时候出现在地质记录中的？为了做到这一点，我们将把世界各地的鲸鱼目击数据与环境数据以及整个新生代海洋条件的最先进重建相结合。最后，我们将重建与迁徙相关的解剖学适应和生态学的进化史。我们会问：在鲸鱼的进化过程中，我们什么时候看到游泳适应和表明迁徙行为的生态位的结合？为了做到这一点，我们将比较整个鲸鱼系统发育树的形态和生态特征，重建最有可能的事件进化序列。这个项目提出了一个独特的方法组合来解决一个重要的进化问题。这不仅将为鲸鱼及其生态、进化和行为提供新的见解；它将揭示一个对海洋生态系统功能至关重要的过程的深时间起源，并为灭绝物种研究中解剖学和生态学证据的结合提供一个案例研究。通过更好地了解鲸鱼迁徙与环境变化之间的关系，我们为理解人为变化对这些标志性海洋巨人未来保护风险的影响奠定了基础。

Whales are a diverse group of aquatic mammals that fill a wide range of important roles within marine communities. One surprising behaviour they exhibit is the remarkable ability to travel huge distances across the world every year in their annual migrations. They migrate from polar regions, where food is plentiful, to regions nearer the tropics where they can raise their young away from predators. Long-distance migration in whales is ecologically important because they transfer huge quantities of nutrients from the food they eat at the poles, which they then release in breeding regions through defecation or by dying. For example, a fallen whale body on the seabed provides the basis for an entire marine ecosystem. While fully-aquatic whales evolved over 40 million years ago, it is unclear when in their long evolutionary history migration began. It has been hypothesized that global climatic change, such as formation of the polar ice caps may have provided the environmental impetus for whale migration, but the link between behaviour, ecology, and evolution is poorly understood.This research will investigate long-distance migration in modern whales, then apply this knowledge to understanding how and when migratory behaviours evolved in ancient whales. We aim to investigate both the functional changes in morphology that enable long-distance migration and the environmental factors that drove the onset of these epic journeys. First, we will investigate how whale body shape has adapted to facilitate long-distance swimming in modern whales. We will ask: are migratory whales biomechanically optimized for swimming long distances? We will do this by measuring body shape variation in whales, and using computer models to estimate the fluid dynamics of whale swimming. Next, we will examine the environmental drivers that underlie whale migration and predict when they arose in earth history. We will ask: How do the environmental conditions in whale breeding and feeding grounds differ? And, when do these particular environments appear in the geological record? To do this, we will combine data from whale sightings around the world with environmental data, and state-of-the-art reconstructions of oceanic conditions throughout the Cenozoic. Finally, we will reconstruct the evolutionary history of both anatomical adaptations and ecology associated with migration. We will ask: When in whale evolution do we see the combination of swimming adaptations and ecological niches that indicate migratory behaviour? To do this, we will compare morphological and ecological features broadly across the phylogenetic tree of whales, reconstructing the most likely evolutionary sequence of events.This project proposes a unique combination of approaches to address an important evolutionary question. This will not only provide new insights into whales, their ecology, evolution, and behaviour; it will shed light on the deep-time origins of a process which is key to oceanic ecosystem function, and provide a case-study for the combination of anatomical and ecological evidence in studies of extinct species. By better understanding the relationship between whale migration and environmental change through time, we lay the groundwork for understanding the impact of anthropogenic changes on the future conservation risks of these iconic ocean giants.