DISSERTATION RESEARCH: Adaptive radiation and hybridization: testing the hybrid swarm origin hypothesis for adaptive radiations in a phylogenetic framework

已知适应性辐射和生态机会在新的生物多样性的形成中发挥重要作用。 在这个模型中，一些祖先物种迅速多样化，以各种新的形态和生态策略填充生态空间。最近，密切相关的物种之间的杂交已被假设在适应性辐射的早期阶段发挥了重要作用，但目前缺乏研究调查这一过程中的植物。该项目将以安第斯植物Lachemilla属（蔷薇科）为模型，评价杂交在促进适应性辐射方面的作用。 Lachemilla包括大约50个描述的物种，仅限于整个安第斯山脉的高海拔栖息地。系统发育分析的叶绿体和单拷贝核DNA基因序列从多个Lachemilla物种将首先被用来重建进化关系。 利用这个进化框架，研究人员将使用各种统计方法来研究杂交在推动谱系内多样化方面所发挥的作用。 这项研究将为研究生提供系统学和进化生物学方面的广泛培训，并加强与厄瓜多尔研究人员的国际科学合作。该项目将为一名本科生提供实验室技术和数据分析方面的培训，并为共同主要研究者提供宝贵的指导经验。该项目将使用系统发育方法，调查和测试的混合群体起源和syngameon假说的功能多样性的产生在适应性辐射使用Lachemilla植物属（蔷薇科）。将使用贝叶斯方法，使用全叶绿体和多个单拷贝核区域的高通量测序方法，从数百个Lachemilla种质中产生稳健和全面的同源性。 这个系统发育框架，然后将用于第一次测试杂交的证据，然后调查是否形态，功能和系统发育的多样化的分支与杂交事件相吻合。通过整合现代比较系统发育措施的性状进化与血统多样化率的复杂分析，本研究将探讨杂交的早期阶段的适应性辐射的明确作用。

Adaptive radiation and ecological opportunity are known to play major roles in the formation of new biodiversity. In this model, a few ancestral species diversify rapidly to fill ecological space with a variety of new morphological and ecological strategies. Recently, hybridization among closely related species has been hypothesized to play an important role during the early stages of an adaptive radiation, but studies investigating this process in plants are currently lacking. This project will evaluate the role of hybridization in facilitating an adaptive radiation using the Andean plant genus Lachemilla (Rosaceae) as a model. Lachemilla comprises approximately 50 described species and is restricted to high elevation habitats throughout the Andes. Phylogenetic analyses of chloroplast and single-copy nuclear DNA gene sequences from multiple Lachemilla species will first be used to reconstruct evolutionary relationships. Using this evolutionary framework, researchers will then use a variety of statistical approaches to investigate the role played by hybridization in driving diversification within the lineage. This research will provide extensive training in systematics and evolutionary biology to a graduate student, and enhance international scientific collaboration with researchers in Ecuador. This project will provide training for one undergraduate student in laboratory techniques and data analysis, and also provide valuable mentoring experience for the co-PI. This project will use phylogenetic methods to investigate and test the hybrid swarm origin and syngameon hypotheses for the generation of functional diversity during an adaptive radiation using the plant genus Lachemilla (Rosaceae). A robust and comprehensive phylogeny from hundreds of Lachemilla accessions using high-throughput sequencing approaches of whole chloroplast and multiple single-copy nuclear regions will be generated using Bayesian approaches. This phylogenetic framework will then be used to first test for evidence of hybridization, and then investigate whether morphological, functional, and phylogenetic diversification in the clade coincides with hybridization events. By integrating modern comparative phylogenetic measures of trait evolution with sophisticated analyses of lineage diversification rates, this research will investigate the explicit role of hybridization in the early stages of an adaptive radiation.