Major factors controlling diversity in Cenozoic terrestrial herbivores

物种多样性是无限的还是受到生态限制的？这些限制是固定的还是波动的？这些限制是由生物竞争施加的，还是由物理驱动因素(如气候)施加的？表型创新是否释放了多样性的生态界限？这些都是进化和宏观生态的关键方面，人们仍然知之甚少。尽管已经开发了几种新的方法(即基于分子系统学)来回答这些问题，但它们在重建过去多样性(物种形成和灭绝之间的平衡)和表型进化方面的动力有限。对于已灭绝的支系或几乎没有活着的代表的支系来说，情况尤其如此。另一方面，古生物学家直到最近(如2015年)才能使用基于过程的方法，这种方法利用化石记录中的信息，但也纳入了可能影响多样性的因素。在这里，我建议应用这种分析方法(包括在PYRATE软件中)来分析新生代陆地大型食草动物(偶蹄目、剑齿目、喙形目；超过2,000种)丰富的化石记录，并调查控制它们多样性的主要因素。我的目标是测试：(I)多元化是否有任何界限，以及(Ii)内在因素(多样性依赖、竞争、捕食、表型创新)在控制多元化方面是否比外部因素(气候、生产率等)起到更普遍的作用。重要的是，在提出的方法中，多样性依赖、竞争、形态空间演化和气候将被直接输入多样化模型，并可以在概率框架中直接进行比较。作为项目的一部分，我将为PYRATE开发新的功能，这将提高我们研究多样性动态和多样化驱动因素的能力，并为三个主要哺乳动物分支的物种形成和灭绝动态提供新的线索。

Is species diversity un-bounded or is it constrained by ecological limits? Are these limits fixed or do they fluctuate? Are these limits imposed by biotic competition, or by physical drivers (e.g. climate)? Do phenotypic innovations release ecological bounds to diversity? These are crucial aspects of evolution and macroecology that remain poorly understood. Although several neontological methods (i.e. based on molecular phylogenies) have been developed to answer these questions, they have limited power to reconstruct the dynamics of both past diversification (the balance between speciation and extinction) and phenotypic evolution. This is especially the case for extinct clades or clades with few living representatives. On the other hand, process-based approaches that use information from the fossil record but also incorporate factors potentially affecting diversity have not been available to paleontologists until very recently (e.g. 2015). I here propose to apply such analytical methods (included in the software PyRate) to analyze the rich fossil record of Cenozoic terrestrial large herbivores (Artiodactyla, Perissodactyla, Proboscidea; over 2,000 species) and to investigate the main factors controlling their diversification. I aim to test: (i) whether diversification has any bounds and (ii) whether intrinsic factors (diversity dependence, competition, predation, phenotypic innovation) have a more prevalent role in controlling diversification than extrinsic factors (climate, productivity, etc.). Importantly, in the proposed approach, diversity-dependence, competition, morphospace evolution and climate will be directly fed into diversification models and can be directly compared in a probabilistic framework. As part of the project I will develop new functionalities for PyRate that will improve our ability to investigate diversity dynamics and diversification drivers, and shed new lights on the speciation and extinction dynamics of three major mammalian clades.