The study of population biology and genetic diversity provides insights to the potential for colonization and can detect geographic patterns of invasion and range expansion, which is essential to predict how species might react to dynamic environments and the global climate change. An outstanding example for a successful colonizer is the Shepherd’s Purse (Capsella bursa-pastoris (L.) Medik.). It is closely related to Arabidopsis thaliana, the “lab rat“ of plant scientists, and originated 100-300 kya from the hybridization between an ancestral C. orientalis and an ancestor from the C. grandiflora/rubella lineage according to the current literature (Douglas et al., 2015). Many species invasions are the direct or indirect consequence of human activities, and the worldwide distribution of the Shepherd’s Purse is partially associated with prehistorical human migration (e.g. Neuffer & Hurka, 1999; Cornille et al., 2016). With the novel genome-wide restriction site-associated DNA sequencing (RADseq) it is possible to perform population genetic studies of unprecedented depth and complexity and allowed the exploration of evolutionary history, range expansion and invasion patterns of this plant species. I will show here that a large number of loci and a wide global sampling area, using seed collections from nearly all over the world covering a large part of the whole distribution area of this ubiquitous weed, reveal finer-scale population structure of C. bursa-pastoris than has previously been detected. The work proposed here generates a comprehensive picture of phenotypic diversity in relationship to genetic variation within C. bursa-pastoris. Genetic variation is clearly geographically structured and split into two lineages apparently adapted to different environments, with one population predominantly distributed in Mediterranean climate regions and the other predominantly in temperate climate regions. The worldwide distribution patterns of the genetic variation can be explained by intra- and intercontinental migration, but environmental filtering due to climate pre-adaption seems also involved. The two clusters point to an early diversification into two lineages or may even suggest multiple origins of the species.This dissertation consists of three papers and manuscripts written during my time as a doctoral student at the Osnabrück University.
| Identifer | oai:union.ndltd.org:uni-osnabrueck.de/oai:repositorium.ub.uni-osnabrueck.de:urn:nbn:de:gbv:700-202007103254 |
| Date | 10 July 2020 |
| Creators | Wesse, Christina |
| Contributors | apl.Prof. Dr. Barbara Neuffer, asst.Prof. Daniel Koenig, PhD |
| Source Sets | Universität Osnabrück |
| Language | English |
| Detected Language | English |
| Type | doc-type:doctoralThesis |
| Format | application/zip, application/pdf |
| Rights | http://rightsstatements.org/vocab/InC/1.0/ |
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