Evolutionary routes to phenotypic convergence in vertebrates

为什么地球上没有更多的生物多样性呢？地球上有数以百万计的物种，但许多远亲物种有着惊人的相似表型，这表明生物多样性实际上远没有我们想象的那么多样化。例如，鲨鱼和海豚的身体形状非常相似，但它们最近的共同祖先生活在2.9亿多年前。这种形式重复的原因之一是趋同进化--不相关物种相似之处的进化。在包括形态、基因、生态环境、生活史策略和行为在内的无数特征中，有数百个趋同的例子。收敛是进化生物学中的一个核心概念，因为它有助于理解许多基本的进化模式和过程，包括限制在进化中的作用、形态多样性、适应性辐射和自然选择。收敛进化通常被认为是地球上生命的一个普遍特征。然而，尽管有许多引人注目的例子和悠久的研究历史，我们目前对趋同的模式和推动趋同的过程缺乏全面的了解。许多例子从来没有得到适当的量化，而那些已经被更彻底地探索的例子使用了各种方法、分类群、特征和标尺，阻止了对一般模式的识别。我们已经确定了两个关键的知识差距和关键问题：1)缺乏对大范围趋同的系统发育模式的了解。因此，我们会问，收敛进化在广泛的系统发育尺度上发生的频率是多少，收敛的例子有多强？2)缺乏对导致进化尺度上的收敛的过程的理解。为了解决这个问题，我们会问，是什么微观和宏观进化机制作用于导致趋同的物种特征？由于缺乏合适的方法和数据，我们在理解推动趋同进化的模式和过程方面的进展一直受到阻碍。回答上述关键问题需要一个新的概念和分析框架，以了解趋同表型是如何演变的。为了解决这些挑战，我们将开发一个框架来衡量趋同进化的程度，并确定最有可能实现表型趋同的进化途径。我们的方法建立在微进化和适应性辐射理论以及研究团队设计的最新方法学进步的基础上。我们将使用我们最近从8,700种鸟类中收集的3D喙形态数据集来开发和测试我们框架的性能，这将使我们能够测试在多个系统发育尺度上的收敛。然后，我们将把我们的框架应用于形态进化的不同例子，以确定在脊椎动物生命树上收敛的广泛模式。这项拟议的研究是及时的，因为这种广度和生态相关性的表型数据集最近才出现(并且在数量和特征/分类覆盖率方面正在迅速增加)，并且与评估收敛的计算方法的重大进展相吻合。我们提议的工作的结果将为我们理解收敛进化提供重大进展。这些进展对于推动我们对进化限制的性质的理解以及由此导致地球上生命多样性的过程的理解发生一步变化至关重要。

Why isn't there more diversity of Life on Earth? There are millions of species on Earth, but many distantly related species have strikingly similar phenotypes, suggesting that biodiversity is in fact far less varied than we might expect. For example, sharks and dolphins have remarkably similar body shapes, but their most recent common ancestor lived over 290 million years ago. One reason for this repetition of forms is convergent evolution - the evolution of similarities in unrelated species. There are hundreds of examples of convergence in myriad traits including morphology, genes, ecological niches, life-history strategies and behaviour. Convergence is a central concept in evolutionary biology because it informs understanding of many fundamental evolutionary patterns and processes, including the role of constraints in evolution, morphological diversity, adaptive radiations and natural selection.Convergent evolution is often considered to be a ubiquitous feature of life on Earth. Yet, despite many striking examples and a long history of study, we currently lack a comprehensive understanding of both patterns of, and processes driving convergence. Many examples have never been properly quantified, and those that have been explored more thoroughly use a variety of methods, taxa, traits, and scales, preventing recognition of general patterns. We have identified two critical knowledge gaps and key questions:1) A lack of understanding of broad-scale phylogenetic patterns of convergence. We will therefore ask, how frequently does convergent evolution occur at broad phylogenetic scales and how strong are examples of convergence?2) A lack of understanding of the processes leading to convergence across evolutionary scales. To address this we will ask, what are the micro- and macroevolutionary mechanisms acting on species traits that lead to convergence?Advances in our understanding of the patterns and processes driving convergent evolution have been hampered by a lack of suitable methods and data. Answering the key questions above requires a new conceptual and analytical framework for understanding how convergent phenotypes evolve. To solve these challenges, we will develop a framework to measure the extent of convergent evolution and identify the most likely evolutionary routes to phenotypic convergence. Our methods build on microevolutionary and adaptive radiation theory, and recent methodological advances designed by the research team. We will develop and test the performance of our framework using our recently collected 3D beak morphology dataset from >8,700 bird species, which will allow us to test for convergence at multiple phylogenetic scales. We will then apply our framework to diverse examples of morphological evolution to identify broad-scale patterns in convergence across the vertebrate tree of life. The proposed research is timely because phenotypic datasets of such breadth and ecological relevance have only recently become available (and are rapidly increasing in number and trait/taxonomic coverage) and coincide with major advances in computational methods to assess convergence.The outcomes of our proposed work will provide a major advance in our understanding of convergent evolution. These advances are critical to driving a step change in our understanding of the nature of limits to evolution and, as a consequence, the processes that gave rise to the diversity of life on Earth.