Collaborative Research: How different forms of competition shape trait evolution and coexistence: A tale of two castes in the turtle ants

地球上各种各样的生命，或称“生物多样性”，对人类赖以生存的自然系统的健康运作至关重要。然而，关于随着时间的推移产生生物多样性并在当今系统中保持生物多样性的机制，还有很多东西需要学习。本研究寻求对竞争在生物多样性“生产和维持”中的机制作用的综合理解的新水平。竞争是一种无处不在的物种相互作用，通常表现为对资源的公开争夺。长期以来，它一直与塑造功能分化的物种群体的进化以及确定哪些物种分类可以在同一地方共同生活有关。然而，关于竞争如何影响生物多样性的生产和维持的综合研究一直难以捉摸。该项目将整合一系列比较进化、生态和实验研究，以确定各种形式的竞争如何在一组生物中形成复杂的形态多样性，以及哪些物种可以在同一栖息地共存。这项研究为塑造地球生物多样性的关键机制提供了潜在的变革性理解，地球生物多样性对人类福祉至关重要，但也日益受到威胁。这项工作的主要科学发现将用于科学与艺术合作，为课堂上和网上的广大受众提供生物多样性生产和维护的视觉指南。此外，该项目将为来自不同背景的年轻科学家提供广泛的培训和指导，并为实体和数字馆藏提供全面的标本贡献。这个项目的目标将利用龟蚁（Cephalotes）来解决，龟蚁是一个多样化的新世界谱系，在蚂蚁中具有标志性的表型多样性，并且在它们所占据的栖息地中具有高度的本地物种丰富度。重要的是，已知不同的龟蚁特征会参与不同形式的竞争：与少数专业化竞争者的高强度“定向”竞争，与多物种组合中低强度但普遍的“扩散”竞争。这项工作将包括：1)物种水平的系统发育比较分析，这些特征与目标竞争和分散竞争的对比；2)物种丰富群落中物种共存与性状多样性的对比分析；3)基于实地的实验研究特质介导的竞争强度和结果严重程度，对比了不同竞争形式定义的场景。被测试的首要假设是，有针对性的竞争形式既推动了更多样化的性状多样性，也推动了更可预测的性状介导的共存机制。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The diverse array of life on earth, or “biodiversity”, is critical for the healthy functioning of the natural systems that humans depend on. Yet there is much to learn about the mechanisms that produce biodiversity through time and then maintain it in present-day systems. This research seeks a new level of integrative understanding of the mechanistic role of competition in this “production and maintenance” of biodiversity. Competition is a ubiquitous species interaction, often apparent as overt fighting over resources. It has long been implicated in shaping the evolution of functionally differentiated groups of species and in determining which assortment of species can live together in the same place. Yet integrated studies of how competition shapes the production and maintenance of biodiversity have been elusive. This project will integrate a series of comparative evolutionary, ecological, and experimental studies to determine how competition, in its various forms, shapes both elaborate morphological diversity within a group of organisms and which of these species can coexist in the same habitat. This research then offers potentially transformative understanding of key mechanisms shaping earth’s biodiversity, which is both critical for human wellbeing and increasingly threatened. The main scientific findings from this work will be used in a science-art collaboration to bring a visual guide to biodiversity production and maintenance to broad audiences in the classroom and online. Additionally, the project will provide extensive training and mentoring for young scientists from diverse backgrounds and make comprehensive specimen contributions to physical and digital collections.The goals of this project will be addressed using the turtle ants (Cephalotes), a diverse New World lineage with iconic phenotypic diversity among ants and high local species richness in the habitats they occupy. Critically, different turtle ant traits are known to engage with different forms of competition: high intensity “targeted” competition with a small number of specialized competitors, versus low intensity but pervasive “diffuse” competition within multi-species assemblages. The proposed work will integrate: 1) species-level phylogenetic comparative analyses of traits that engage with contrasting targeted versus diffuse competition; 2) analyses of species coexistence and trait diversity for contrasting forms of competition in species-rich communities; and 3) field-based experimental studies of trait-mediated competitive intensity and outcome severity, contrasted across scenarios defined by different forms of competition. The overarching hypothesis being tested is that targeted forms of competition drive both more divergent trait diversity and more predictable trait-mediated mechanisms of coexistence.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.