PhD. Topics

Elucidating speciation processes and polyploid evolution in Erysimum (Brassicaceae): an integrative approach

genetics

Mgr. Judita Zozomová, PhD.

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Prírodovedecká fakulta UK

Addressing speciation processes and evolution in recently diverged, but species-rich plant genera is a challenging research topic. High diversity along with shallow structure, low resolution and phylogenetic incongruence have been characteristic for such lineages, in many cases attributable to rapid radiations, but it is now increasingly recognized that reticulation events (i.e., introgression, hybridization, polyploidization) have also played a significant, perhaps even predominant role in their evolution. Phylogenomic analyses of wild (non-model) polyploid and hybridogenous lineages have lagged behind until recently, mainly caused by their evolutionary complexity, methodological and computational difficulties. However, recent advances in high-throughput DNA sequencing, in cytogenomic techniques, and in analytical methods to detect hybridization and resolve polyploidization events, offer new possibilities and perspectives in such studies. The PhD thesis should follow these recent advances, which will be reflected both in the research focus and the proposed methodology. It will address two related species complexes of the genus Erysimum (E. odoratum and E. virgatum groups), which provide excellent resources for studying both recent divergence and reticulate evolution. The genus is taxonomically and evolutionarily complex, which stems from multiple factors, such as recent and rapid radiation, high chromosome number diversity, abundance of polyploids, presence of cryptic species, as well as interspecific hybridization. The aims of the thesis will be to resolve phylogenetic relationships in the studied species groups, revise species circumscriptions, reconstruct polyploid origins, and examine genome divergence and evolution in polyploid lineages. Speciation mechanisms that have triggered their diversification will be explored, focusing on the role of ecological divergence, gene flow barriers due to geographic isolation, polyploidization and hybridization events. It will be tested whether the high endemism rate reflects multiple independent polyploidization events or increased speciation rate of polyploid lineages. An integrative methodological approach will be taken, which will combine phylogenomic methods, cytogenomic, cytometric, morphometric and ecological niche analyses.