Variation und Variabilität der Unterkieferform in der Hausmaus

• Main Author: Boell, L.
• Format: Doctoral or Postdoctoral Thesis
• Language: German
• Published: Christian-Albrechts-Universität 2010
• Subjects: Kerguelen Islands
• Online Access: http://hdl.handle.net/11858/00-001M-0000-000F-D474-9; http://hdl.handle.net/11858/00-001M-0000-000F-D473-B

In this thesis, I provide a description of the shape space of wild mouse mandibles with a focus on Mus musculus. Extending the comparisons to captive mice, inbred strains and some experimental populations, I try to infer which biological processes might account for observed patterns of shape variation, including genetic and developmental aspects (variability). I obtain the following results: 1) Mahalanobis distances based on CVA of Procrustes coordinates are a good measure of the global shape difference between two populations. Combined with the use of two-dimensional projections of μCT images of mouse hemimandibles, they are sufficiently robust in the face of diverse problems with sample quality and data processing, such as limitations in sample size, sampling errors with respect to sex, age and size of the animals, orientation of the samples inside the μCT scanner, preparation of bones and landmark digitization error. 2) Phenotypic plasticity as a reaction to environmental differences affects mandible shape by a smaller amount than the average distance between samples of wild-caught populations, suggesting that the shape differences between wild populations mostly have a genetic basis. 3) Various types of selection may have acted on shape. Four populations of mice from summer-dry regions cluster closely together, indicating that stabilizing selection may have conserved their shape. A M. m. domesticus sample from a site in Spain where the mice live in sympatry with a population of M. spretus is highly divergent from other M. musculus. This could represent a case of character displacement. Two populations of M. m. domesticus representing rather recent events of colonization on the subantarctic Kerguelen islands have diverged from other M. musculus in partially similar directions, which could represent an adaptation to the cold climate on these islands. 4) Inbred mouse strains are more divergent from wild mice and from each other than different species in nature, suggesting that nonadditive mechanisms of ...