000K  utf8
1100  $c2004
1500  eng
2050  urn:nbn:de:gbv:8-diss-12060
3000  Wegner, K. Mathias
4000  Major histocompatibility genes, polymorphism and balancing selection : the case of parasites and sticklebacks$hChristian-Albrechts-Universität zu Kiel  [Wegner, K. Mathias]
4030  Kiel$nChristian-Albrechts-Universität zu Kiel
4209  The extreme polymorphism of genes of the vertebrate major histocompatibility complex is an evolutionary puzzle. Why do high numbers of alleles persist despite selective forces favouring the fittest variants? Overdominant selection can explain the persistance of high numbers of alleles, because MHC heterozygotes can detect more pathogens. Using three-spined sticklebacks and their natural parasite fauna as a model organisms, this thesis addresses some of the key mechanisms that may explain MHC polymorphism. On Population level, diversity of stickleback MHC class IIB genes was correlated with parasite diversity. Within individuals those with an intermediate individual MHC diversity were suffering least from parasite infection in the field and in controlled experiments. Host-parasite co-evolution would further predict that the fitness of genotypes/alleles should fluctuate depending on its frequency. In three populations MHC alleles fluctuate stronger between generations than random. These fluctuations could partly be linked to changes in parasite prevalence and therefore provide support for antagonistic co-evolution between MHC genes and parasites.
4950  https://nbn-resolving.org/urn:nbn:de:gbv:8-diss-12060$xR$3Volltext$534
4961  https://macau.uni-kiel.de/receive/diss_mods_00001206
5051  570
5550  co-evolution
5550  Dreistachliger Stichling
5550  frequency dependent selection
5550  Gasterosteus aculeatus
5550  major histocompatilibility complex
5550  MHC
5550  overdominant selection
5550  Parasit
5550  parasites
5550  three-spined stickleback