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PhD. Topics

Plant Science and Biodiversity Centre SAS

Taxonomy, speciation processes and polyploid evolution in Erysimum (Brassicaceae)
PhD. program
Name of the supervisor
Mgr. Judita Zozomová, PhD.
Receiving school
Faculty of Natural Sciences of Comenius University
Recently diverged and species-rich vascular plant genera are interesting objects of study with regard to
their evolution and taxonomy. High diversity together with shallow structure, low resolution and
phylogenetic incongruence have been characteristic for such lineages, in many cases attributable to rapid
radiations. Reticulation events (introgression, hybridization, polyploidization), however, 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 highthroughput DNA sequencing 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 relationships and origin of multiple
cytotypes and polyploids, 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, chromosomal rearrangements, polyploidization
and hybridization events. An integrative methodological approach will be taken, which will combine
phylogenomic methods, cytogenomic, cytometric, morphometric and ecological niche analyses.