Diversity Dynamics of Middle Paleozoic Marine Animals

中古生代海洋动物的多样性动态研究多样性动力学的主题是探索世界上物种的数量如何以及为什么会随着时间的推移而变化。这项研究将利用大约4.4亿至3.5亿年前古生代中期的海洋动物数据来探索多样性动态。化石群落的物种组成将被编目，这些群落的古代地理和环境背景将被确定。利用这一新信息以及来自其他来源的现有数据，将估计动物属(由一个或多个相关物种组成的更具包容性的分类单位)的起源和灭绝时间。这将允许重建多样性、起源和灭绝的时间模式，这些时间模式将反过来被用来评估多样性的动态。当多样性在数百万年内增加时，这往往是因为新物种的生产速度增加了，还是因为现有物种的灭绝速度减少了？同样，多样性的下降是以起源的减少还是灭绝的增加为标志？换句话说，在调节生物多样性方面，起源和灭绝哪个更重要？以往的研究表明，在动物进化的过程中，物种多样性的动态变化，在动物历史的前3亿年(古生代)，灭绝更加重要，而起源在之后(中生代和新生代)更加重要。有理由认为，多样性动态可能会因地理和环境而异。这项研究将首次验证以下预测，即就多样性调节而言，物种灭绝在热带地区比温带更重要，在浅水环境中比深水环境更重要。此外，据了解，浅海和热带海洋环境在古生代比晚些时候更普遍。因此，这项研究的结果对于确定所观察到的多样性动态的长期时间变化是否可能受到海洋领域某些环境和地理环境的普遍变化的影响，将具有重要意义。

ABSTRACTDiversity Dynamics of Middle Paleozoic Marine AnimalsMichael FooteEAR-0105609The subject of diversity dynamics explores how and why the number of species in the world changes over time. This research will explore diversity dynamics with data on marine animals from the middle of the Paleozoic Era, about 440 to 350 million years ago. The species composition of fossil communities will be inventoried, and the ancient geographic and environmental setting of these communities will be determined. Using this new information as well as existing data from other sources, the times of origination and extinction of animal genera (the more inclusive taxonomic units that consist of one or more related species) will be estimated. This will allow the temporal patterns of diversity, origination, and extinction to be reconstructed, and these temporal patterns in turn will be used to assess the dynamics of diversity. When diversity increases over millions of years, does this tend to occur because the rate of production of new species has increased or because the rate of extinction of existing species has decreased? Likewise, does a decline in diversity tend to be marked by a decrease in origination or an increase in extinction? In other words, is origination or extinction more important in regulating biological diversity? Previous research shows that the style of diversity dynamics changes over the course of animal evolution, with extinction more important for about the first 300 million years of the history of animals (during the Paleozoic Era) and origination more important thereafter (during the Mesozoic and Cenozoic Eras). There are reasons to think that diversity dynamics may vary geographically and environmentally. This research will be the first to test the predictions that, as far as diversity regulation is concerned, extinction is more important in the tropics than in the temperate zones and more important in shallow-water environments than in deeper waters. In addition, it is known that shallow marine and tropical marine environments were more prevalent in the Paleozoic Era than later. The results of this research will therefore be significant in determining whether the observed, long-term temporal change in diversity dynamics may be underlain by a change in the prevalence of certain environmental and geographic settings in the marine realm.