Evolutionary principles and the genomic basis of convergent evolution of traits and characters in the Arabideae.

• Applicant: Professor Dr. Marcus Koch
• Subject Area: Evolution and Systematics of Plants and Fungi
• Term: since 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 367498337

Life in general, and plants in particular, adapt to a new environment on evolutionary time scales. Studying adaptation is essential if we aim at understanding how life persists in the face of changing environments, a topic of immediate relevance in today’s world. The study of adaptation is often limited by a lack of replication and without independent replication it is impossible to determine how much of what we see in nature is particular to a certain example and how much can be regarded as a general result or rule. However, convergent evolution allows us to overcome this fundamental limitation, as this process is nature’s own replicate experiment in generating a phenotype. This leads very often to convergent evolution. Convergent evolution describes the independent development of the same phenotype in different evolutionary lineages. The observation of convergence has fascinated humans since Darwinian times already and it is still puzzling how nature is being able to invent the same solution for a problem in distantly related species. Most intuitively convergent evolution is the result of adaptation to similar conditions. However, it can also be the result of constraint, e.g. developmental or mutational. Furthermore, introgression can also be considered as a source for convergence, a notion which is of particular interest when studying convergent evolution in plants where polyploidization, reticulate evolution and hybridization are a common phenomenon. Studying convergent evolution requires the availability of a large number of natural replicates, i.e. groups of taxa where multiple sister lineages are found that differ in the traits to be analysed. Within the Brassicaceae family the tribe Arabideae is one of the most prominent tribes and it displays exactly this required feature. It is a monophyletic assemblage with roughly 500 species distributed among 18 accepted genera where convergence of traits and trait complexes is found in all main lineages. With our project we are using comparative genomic approaches to seek for genomic footprints of parallel evolution of the plants morphospace explaining convergent phenotypes and also selected complex traits. It is often seen that some of the characters and traits are combined and show even convergence as a syndrome. Here we focus on one of the most extreme traits, namely evolution of monocarpic (annual) versus polycarpic (perennial) life history, which has evolved many times independently in Brassicaceae. Spatio-temporal environmental evidence will be collected indirectly from data on distribution ranges and divergence time estimates. We seek for deepening our insights into the principles of Brassicaeae evolution in order to understand better the successfully evolutionary history of a large plant family diversifying at highest rates.

• DFG Programme: Research Grants
• Co-Investigator: Dr. Christiane Kiefer