While the house mouse is one of the major model in genetic engineering for scientific research, it is also a good candidate to understand evolutionary features. Yet, still few is known concerning how skull and teeth shape evolved among the different natural populations; and whether these differences can be functional. Furthermore the genetic determinism of skeletal shape variation are not known in that context. Having spread with Human in all places of the world, the house mouse can be found in several environments. The geographic origin of the house mouse is certainly close to the Iranian plateau where most of the genetic variation across populations can be found today. Interestingly, the house mouse is very variable in skull and teeth shape morphology. By using morphometrics, one can show that the shape features of the skull and the teeth are correlating well with the supposed dispersal of the house mouse. So far, little is known concerning the role of genetic and environmental variation on shape and size of skull and teeth features in natural populations. We started studying the teeth and mandible shape of two populations from two completely different origins. We made pedigrees from mice trapped from these populations and exposed progenies to different diet. We found that the mandible shape depended on diet and was subject to phenotypic plasticity, while tooth morphology was not. The mandible phenotypic response to diet shift was different between populations suggesting different reaction norms. As expected, we found several similarities in genetic variation of shape features between populations when these populations were receiving normal food. But we also found that the genetic variation could be expressed differently when a different and unusual diet was provided (ie. environmental conditions). This suggests that the evolutionary potential of populations depends not only on the genetic of groups but also to environmental conditions. Although house mouse populations tend to differ depending on their divergence, history and genetics can still correlate well with the morphology of the skull and teeth at much finer scales. The house mouse has colonized several islands. In that context, we have been studying a set of populations in the Orkney Archipelago in Scotland. These populations display an important variation in tooth morphology and mandible shape, that is furthermore structured among the different islands constituting the archipelago. Morphological variation correlates well with the genetic structure of the populations. Some aspects of the variation were surprisingly observed in other populations of mice in insular context

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