RUI: SG: Identification of evolutionary processes driving plant diversification on Madagascar in Megistohibiscus (Malvaceae)

Eastern Michigan University, Ypsilanti MI

Investigators

Abstract

One of the most important aims of evolutionary biology is to understand the processes responsible for speciation, and one of the best places to study species is on the island of Madagascar. The island is home to an extraordinary number of charismatic plant species and has been identified as an ideal region to investigate the processes of species diversification. This work will provide insight into how such a remarkable flora came to be. Though many ideas have been suggested as possible mechanisms for diversification on Madagascar, the evolutionary processes responsible for the island's botanical biodiversity remain poorly understood. This research will fill this gap in knowledge, test many existing hypotheses for the first time, and provide a much-needed synthesis of evolutionary process for plant diversity on the island. Powerful, new sequencing technologies and innovative analyses will be applied to a species-rich plant group, called Megistohibiscus, which has evolved exclusively on the island. Madagascar is also one of the highest priority areas for biodiversity conservation in the world and genomic data collected for this project have the potential to guide conservation decisions and help limit further losses of biodiversity. The research will provide research opportunities for female undergraduate students and underrepresented minorities at Eastern Michigan and provide important training in evolutionary genetics, systematics, bioinformatics, and conservation. One Malagasy graduate student will be involved in the research and a short course will be taught at the country's major university to facilitate international scientific exchange and address the significant shortage of trained local scientists on Madagascar. This research will synthesize findings from phylogenetic and phylogeographic investigations, information theory and ecological niche modeling to explore the mechanisms that have led to the extraordinary diversification of plants on Madagascar. Because multiple processes have likely contributed to the evolution of the flora, the work will evaluate a full range of evolutionary forces (and assess their relative contributions) in order to identify the most important processes. Speciation hypotheses will be rigorously tested for the first time in Malagasy plants and focus on a morphologically diverse, monophyletic and endemic clade (Megistohibiscus) in an important Malagasy plant family (Malvaceae; tribe Hibisceae). Analyses of genetic data collected via RAD tag Illumina sequencing will identify mechanisms promoting diversification at the species and population level. This research specifically aims to: I) Infer patterns and timing of diversification in Megistohibiscus; II) Integrate phylogenetic, geographic and temporal information to explicitly test models of speciation; III) Explore phylogeographic histories in three endemic genera (Humbertiella, Megistostegium, and Perrierophytum); and IV) Identify, rank and compare demographic processes responsible for population diversification. The resulting taxonomically complete and resolved phylogeny of Megistohibiscus will help delimit species boundaries, revise taxonomy, and provide insights into relationships of the Malagasy flora. A Malagasy Plant Evolution Working Group will be assembled to assess and strategize ways to inspire the future execution of speciation studies in other endemic plant clades to uncover comprehensive patterns of Madagascar's floristic diversity. American undergraduate students and a student from Madagascar will be trained at Eastern Michigan University, an RUI Institution, in all aspects of the research.