Microsatellites and Genetic Variation in Two Members of the African PapioniniDissertation
Datum der mündl. Prüfung:2022-11-01
Betreuer:Prof. Dr. Julia Fischer
Gutachter:Prof. Dr. Julia Fischer
Gutachter:Dr. Christian Roos
EnglischThe importance of genetic variation for the fitness and viability of populations and species has been shown in many studies over the last decades. However, the way to determine such genetic variation has changed and evolved due to theoretical as well as technical advances. In wildlife studies, the current markers of choice are often still microsatellites. Microsatellites are highly abundant in eukaryote genomes, the majority is located in the non-coding parts of the genomes and therefore assumed to evolve neutrally without selection pressure. They show high levels of allelic diversity ensuring high statistical power per locus and because they are comparatively short, they can be analyzed even from samples of low quality such as feces. Further, microsatellites are often not species-specific and can be amplified across species boundaries. This allows for the fast and easy implementation of a microsatellite panel in closely related species with comparatively little effort. Therefore, they are widely applied in a wide range of studies for example for the identification of individuals, clarification of paternities, the assessment of relatedness and the population level genetic diversity as well as for the monitoring of gene flow among populations and hybridization between (sub-)species. To test the ease of implementation for a microsatellite panel in a cross-species approach and whether the usage of microsatellites can provide a sufficient amount of data, I conducted a study in geladas to investigate their population genetic structure. This study is the first to analyze the nuclear genetic variation in geladas (Theropithecus gelada) using samples originating from all three populations covering their known distribution range. By using a panel of 24 microsatellite loci previously developed and adapted to the genus Papio I could show that the cross-species amplification of microsatellites allows for the fast and easy generation of nuclear genetic data in geladas. Further, the resulting data confirmed a three-deme population structure and therefore provided additional support for the existence of three evolutionary units (or subspecies) within geladas which is still debated based on previous studies using mitochondrial data. The second study presented here deals with several problems that have been identified in the past for the analysis of microsatellites. These include problems due to the current standard way of analysis using capillary electrophoresis such as the high costs, the challenging data evaluation, and the underestimation of genetic variation due to undetected sequence variants in alleles. Additionally, the situation in non-human catarrhine primates is further complicated as many different microsatellite panels have been analyzed across and within species. This hinders the easy sharing, combination, and comparison of data produced by different research groups. Therefore, I present the development and validation of a microsatellite panel that can be universally applied to all catarrhine species incorporated into a genotyping-by-sequencing approach. The resulting panel of 42 microsatellite loci can be applied to all catarrhine primates and facilitates the fast and accurate generation of nuclear genetic data from various sample sources including such with low-quality DNA. Overall, this thesis highlights the applicability of microsatellites in wildlife studies and specifically provides a new tool to analyze nuclear genetic variation in non-human catarrhine primates.
Keywords: Microsatellite; Papionini; Genetic Variation; Gelada; Theropithecus gelada; Population Genetics; Genotyping; Catarrhine primates; genotyping-by-sequencing; high-throughput sequencing; simple tandem repeats