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Collaborative Research: Novel framework for estimating continuously-varying diversification rates

合作研究：估计不断变化的多样化率的新框架

基本信息

批准号：
1916539
负责人：
Brian O'Meara
金额：
$ 19.34万
依托单位：
University of Tennessee Knoxville
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-08-01 至 2024-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1916539&HistoricalAwards=false
关键词：
Collaborative Research Novel framework estimating

项目摘要

Determining the factors that have shaped the huge differences in the number of species among groups of organisms, such as insects versus mammals, has long been of interest to both biologists and paleontologists. Mathematical models for understanding differences in species diversity use two quantities, the rate of speciation (when one species becomes two) and the rate of extinction (when a species disappears). These quantities are similar to those used in studying human populations, the birth rate and death rate. Although paleontologists have proposed explanations for differences in the numbers of species, biologists, using mostly family trees of species based on the analysis of genetic data, have largely concluded that speciation is more important than extinction in explaining these patterns. The central theme of this research is that what drives modern species diversity is not differences in speciation, but rather the differences in "turnover rate," which is defined as the birth rate minus the death rate. Turnover rate measures how often extinction and speciation events happen over long periods of time. This research will expand existing mathematical models for estimating species diversity to include new models that use quantities, such as turnover rate, that are much more tied to biology. The project will also provide a training workshop in these computational skills in the southeastern U.S., an important and underrepresented part of the country. This workshop will train students and other early career researchers to become a computationally literate STEM workforce, which is important to the economic well-being of the nation. The project will also provide professional training opportunities for two postdoctoral researchers.Darwin's great insight was a rejection of typological thinking in favor of recognizing the variation across life. Yet, in diversification analyses, typological thinking is not just a convenient crutch made for methodological convenience. Finding the points at which species shift from one rate "type" instantly to another has received unjustified attention. This research will move away from this typological thinking, towards more biological realism by assuming that diversification rates continuously vary. Central to this framework is a theme of rate "inheritance," where diversification rates evolve and are inherited from ancestor to descendant, much in the same way as a trait would evolve on a tree. Rather than focusing on speciation and extinction, or even net diversification, this research will focus biological interpretations on estimates of turnover and extinction fraction. The overarching hypothesis is that extinction fraction is near but probably somewhat less than one. In other words, speciation events slightly outnumber extinction events over time. What drives diversification patterns, therefore, is not speciation rate varying independent of extinction, or even extinction rate varying, but rather the overall turnover rate. This research will develop a new likelihood-based framework that evaluates a large family of diversification models that more realistically treat rates as continuously varying on a tree and focuses estimation on a new and more mechanistic parameterization.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

长期以来，生物学家和古生物学家都感兴趣的是，确定造成昆虫和哺乳动物等生物群体物种数量巨大差异的因素。理解物种多样性差异的数学模型使用两个量，物种形成率(当一个物种变成两个物种时)和灭绝速度(当一个物种消失时)。这些数值与研究人口、出生率和死亡率时使用的数值相似。尽管古生物学家对物种数量的差异提出了解释，但生物学家基本上得出结论，在解释这些模式时，物种形成比物种灭绝更重要。生物学家主要使用基于遗传数据分析的物种谱系图。这项研究的中心主题是，推动现代物种多样性的不是物种形成的差异，而是“周转率”的差异，“周转率”的定义是出生率减去死亡率。周转率衡量灭绝和物种形成事件在很长一段时间内发生的频率。这项研究将扩展现有的估计物种多样性的数学模型，包括使用数量的新模型，如周转率，这些数量与生物学联系得更紧密。该项目还将在美国东南部提供这些计算技能的培训研讨会，美国东南部是美国一个重要且代表性较低的地区。该研讨会将培训学生和其他早期职业研究人员，使他们成为一名懂计算机的STEM劳动力，这对国家的经济福祉非常重要。该项目还将为两名博士后研究人员提供专业培训机会。达尔文的伟大洞察力是拒绝类型学思维，支持认识生命中的变异。然而，在多元化分析中，类型学思维不仅仅是为了方法论上的便利而制造的便利拐杖。寻找物种从一种速率“类型”立即转变为另一种速率“类型”的时间点，受到了不合理的关注。这项研究将摆脱这种类型学思维，通过假设多样化比率不断变化，走向更多的生物现实主义。这个框架的核心是一个比率“遗传”的主题，即多样化比率的演变和从祖先到后代的遗传，很大程度上就像一个性状在树上进化一样。这项研究不会专注于物种形成和灭绝，甚至不会关注净多样化，而是将生物学解释集中在营业额和灭绝比例的估计上。最重要的假设是，灭绝比例接近，但可能略低于1。换句话说，随着时间的推移，物种形成事件的数量略多于灭绝事件。因此，驱动多样化模式的不是物种形成率独立于灭绝而变化，甚至不是物种灭绝速率变化，而是整体周转率。这项研究将开发一个新的基于可能性的框架，评估一大类多样化模型，这些模型更现实地将比率视为在树上连续变化，并将估计集中在新的和更机械的参数化上。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。