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？大量证据表明，寄生虫在生物多样性的起源和维持中都起着重要作用。这个项目的重点是地球上最多样化的生物群体之一：食草昆虫、它们的寄生虫和它们的微生物。该项目针对三种经济上重要的生物群体：南瓜/黄瓜家族的植物，攻击这些植物的真果蝇，以及杀死苍蝇的寄生蜂。这些黄蜂属于一个高度多样化和很少被研究的物种群。每一种黄蜂只能杀死一种苍蝇；黄蜂攻击“错误”种类的苍蝇会死亡。这些双向致命的相互作用可能是由微生物（在黄蜂、苍蝇或两者中）、苍蝇免疫系统的特性或两者共同介导的。该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。许多种类的真果蝇是主要的农业害虫；该项目将大大增加对影响其对拟寄生虫易感性因素的认识。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化率；2)不同谱系的毒力机制不同，3)由捕食者-猎物相互作用产生的选择可以影响物种形成的速率。为了发现和确定多样化机制，参与者将生成和分析分子1)高分辨率遗传数据，多个核位点和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，用于发现和量化群体内部和群体之间的精细遗传多样性；3)在古代、近代和当代时间尺度上进行系统发育和实地实验，以检验关于产生和控制多样性机制的假设。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.