Collaborative Research: Integrating Phylogenomics with the Fossil Record: Sea Urchins as a Model Clade for Macroevolutionary Research

刺覆盖，球形海胆是标志性的海洋动物常见于海带森林和珊瑚礁，在那里他们往往是藻类和其他生物的主要消费者。相比之下，沙元是非常扁平的海胆，通常生活在桑迪海底，通过从沉积物中拾取微小的食物颗粒来进食。多条证据表明这两个群体是密切相关的，起源于一个身体形态和生态与现代海胆大致相似的祖先。这表明进化路径上存在着鲜明的对比：虽然有些谱系在数亿年中几乎没有变化，但其他谱系却发生了巨大的创新。确定这些不同轨迹的机制对于理解产生和维持生物多样性的过程是必要的。然而，这样做需要准确重建过去发生的事件，并整合基因组，形态学和古生物学信息。该项目强调这些有魅力的动物作为研究进化变化的模型，包括本科生研究计划，教师研讨会和公共博物馆展览等各种推广模式。该项目专注于开发海胆基因组资源，以提高我们对活海胆，沙元和盟友（统称为海胆）之间进化关系的认识。考虑到该分支杰出的化石记录，这些数据将与形态和地层信息相结合，使用全证据测年方法，使所有主要的生活和化石海胆谱系被放置在一个共同的，时间校准的生命树中。使用系统发育比较方法，该项目将揭示与不规则棘球蚴和沙元的起源相关的进化过程，这是身体计划创新的两个主要事件。分析将依赖于一个大规模的海胆身体测量数据集，以探索进化速率和模块化的变化，并将这些指标的变化与已知的发展创新和生态专业化事件相关联。生态，发育和形态特征的贡献，物种形成和灭绝动态将使用国家依赖的多样化模型进行评估。最后，基于本体的祖先状态重建将有助于确定沙元形态类型的独立起源（和损失）的数量，以及这些事件的相对时间。通过结合基因组学和系统发生古生物学的最新发展，该项目将建立棘虫作为宏观进化研究的模式分支。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Spine-covered, globular sea urchins are iconic marine animals common in kelp forests and coral reefs, where they are often the main consumers of algae and other organisms. By contrast, sand dollars are extremely flattened urchins that generally live buried in sandy seafloors, feeding by picking tiny particles of food from the sediment. Multiple lines of evidence suggest these two groups are closely related, originating from an ancestor whose body form and ecology were broadly similar to those of modern sea urchins. This suggests a striking contrast in evolutionary pathways: while some lineages have barely changed over hundreds of millions of years, others have innovated dramatically. Identifying the mechanisms that underlie these different trajectories is necessary to understand the processes generating and maintaining biological diversity. However, doing so requires accurate reconstructions of events that took place in the deep past, and integrating genomic, morphological, and paleontological information. The project highlights these charismatic animals as models for studying evolutionary change in a variety of outreach modes including undergraduate research programs, teacher workshops, and displays in public museums.The project focuses on developing phylogenomic resources to improve our knowledge of evolutionary relationships among living sea urchins, sand dollars and allies (collectively known as echinoids). Given the clade’s outstanding fossil record, these data will be combined with morphological and stratigraphic information using a total-evidence dating approach, allowing all major lineages of living and fossil echinoids to be placed in a common, time-calibrated tree of life. Using phylogenetic comparative methods, the project will reveal evolutionary processes associated with the origins of both irregular echinoids and sand dollars, two major events in body-plan innovation. Analyses will rely on a large-scale dataset of echinoid body measurements to explore changes in evolutionary rate and modularity, and correlate shifts in these metrics with known events of developmental innovation and ecological specialization. The contributions of ecological, developmental and morphological traits to speciation and extinction dynamics will be assessed using state-dependent models of diversification. Finally, ontology-informed ancestral state reconstructions will help identify the number of independent origins (and losses) of the sand dollar morphotype, as well as the relative timing of these events. By combining recent developments in phylogenomics and phylogenetic paleobiology, this project will establish echinoids as a model clade in macroevolutionary research.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.