Dimensions: Collaborative Research: Diversification Dynamics of Multitrophic Interactions in Tropical Communities

生物多样性是如何产生和维持的？许多证据表明，寄生虫在生物多样性的起源和维持方面都发挥着重要作用。这个项目的重点是地球上最多样化的有机体之一：草食性昆虫、它们的寄生虫和它们的微生物。该项目的目标是三类具有重要经济意义的生物：南瓜/黄瓜科植物、攻击这些植物的果蝇以及杀死果蝇的寄生黄蜂。这些黄蜂属于高度多样化且鲜有研究的物种群体。每种黄蜂只能杀死一种苍蝇；攻击“错误的”苍蝇物种的黄蜂会死亡。这些双向致死相互作用可能由微生物(黄蜂、苍蝇或两者兼而有之)、苍蝇免疫系统的特性或两者兼而有之。这个项目旨在揭示影响相互作用的机制(进化、生态和免疫)，这可能有助于解释生命的多样性。许多真正的果蝇是主要的农业害虫；这个项目将极大地增加对它们对寄生蜂易感性的因素的了解。该项目测试的假设预测：1)寄生虫及其宿主的防御影响多样性比率；2)不同谱系的毒力机制不同；以及3)捕食者-猎物相互作用产生的选择可能影响物种形成速度。为了发现和确定多样性的机制，参与者将生成和分析分子1)高分辨率遗传数据、多个核基因座和mtCOI单倍型，以描绘物种，并解决更深层次的系统发育关系；2)微卫星和ddRAD-SEQ标记，以发现和量化种群内和种群之间的精细遗传多样性；3)系统发育和实地实验，以测试关于古代、现代和当代时间尺度上多样性产生和控制机制的假说。来自所有参与院校的本科生将参与研究。

How is biodiversity generated and maintained? Much evidence suggests that parasites play an important role in both the origin and the maintenance of biological diversity. This project focuses on one of the most diverse groups of organisms on the planet: herbivorous insects, their parasites, and their microbes. The project targets three economically important groups of organisms: plants in the pumpkin/cucumber family, true fruit flies that attack these plants, and parasitic wasps that kill the flies. These wasps belong to a highly diverse and little studied group of species. Each wasp species can kill only one fly species; wasps attacking the "wrong" species of fly die. These bi-directional lethal interactions may be mediated by microbes (in wasps, flies, or both), by traits of flies' immune systems, or both. This project is designed to uncover the mechanisms (evolutionary, ecological, and immunological) affecting interactions that may help explain the diversity of life. Many species of true fruit flies are major agricultural pests; this project will greatly increase knowledge about factors contributing to their susceptibility to parasitoids. The project tests hypotheses that predict that: 1) defenses of parasites and their hosts affect diversification rates; 2) mechanisms of virulence differ among lineages, and 3) selection arising from predator-prey interactions can affect rates of species-formation. To discover and identify mechanisms of diversification, participants will generate and analyze molecular 1) high-resolution genetic data, multiple nuclear loci, and mtCOI haplotypes to delineate species, and resolve deeper phylogenetic relationships; 2) microsatellites and ddRAD-seq markers to discover and quantify fine-scale genetic diversity within and among populations; 3) phylogenies and field experiments to test hypotheses about mechanisms generating and controlling diversity on ancient, recent, and contemporary timescales. Undergraduate students from all participating colleges and universities will participate in the research.