Micro-evolutionary divergence patterns of mandible shapes in wild house mouse (Mus musculus) populations

Abstract

BackgroundInsights into the micro-evolutionary patterns of morphological traits require an assessment of the natural variation of the trait within and between populations and closely related species. The mouse mandible is a particularly suitable morphological trait for such an analysis, since it has long been used as a model to study the quantitative genetics of shape. In addition, many distinct populations, sub-species and closely related species are known for the house mouse. However, morphological comparisons among wild caught animals require an assessment in how far environmental and technical factors could interfere with the shape change measurements.ResultsUsing geometric morphometrics, we have surveyed mandible shapes in 15 natural populations of the genus Mus, with a focus on the subspecies Mus musculus domesticus. In parallel we have carefully assessed possibly confounding technical and biological factors. We find that there are distinct differences on average between populations, subspecies and species, but these differences are smaller than differences between individuals within populations. Populations from summer-dry regions, although more ancestral, are less distinct from each other than are populations from the more recently colonized northern areas. Populations with especially distinct shapes occur in an area of sympatry of M. m. domesticus and M. spretus and on recently colonized sub-antarctic islands. We have also studied a number of inbred strains to assess in how far their mandible shapes resemble those from the wild. We find that they fall indeed into the shape space of natural variation between individuals in populations.ConclusionsAlthough mandible shapes in natural populations can be influenced by environmental variables, these influences are insufficient to explain the average extent of shape differences between populations, such that evolutionary processes must be invoked to explain this level of diversity. We discuss that adaptive evolution may contribute to shape changes between populations, in particular in newly colonized areas. A comparison between inbred strains and wild mice suggests that the laboratory environment has no major systematic effect on the mandible shape and that such strains can be used as representatives of the natural shape differences between individuals.

Craniofacial shape transition across the house mouse hybrid zone: implications for the genetic architecture and evolution of between-species differences

“…Although some specific adaptations appear to occur when new habitats or islands are invaded (Renaud and Auffray 2010;Boell and Tautz 2011;Renaud et al 2013;Babiker and Tautz 2015), these remain subtle. Hence, the divergence between separated mouse populations and subspecies may be equally influenced by neutral accumulation of allelic differences.…”

“…Several studies have explored craniofacial shape variation between subspecies of the house mouse (Mus musculus) around the world (Macholán 2006;Boell and Tautz 2011;Siahsarvie et al 2012). The effect of hybridization on craniofacial traits has been studied using wild hybrid mice (Alibert et al 1994;Auffray et al 1996;Mikula and Macholán 2008;Mikula et al 2010), as well as wildderived inbred lines representing different subspecies (Renaud et al 2009(Renaud et al , 2012.…”

Semi-automatic landmark point annotation for geometric morphometrics

“…through functional morphology or shape spaces, than could be achieved through traditional morphometrics, and provide a route to phylogeny reconstruction (e.g. [3,4]). In combination with other data, they can also be used to establish correlations between ecological factors and shape (e.g.…”

Evidence of the island rule and microevolution in white-footed mice (Peromyscus leucopus) in an urban harbor archipelago

“…Divergence of insular house mice from mainland populations is frequently noted through microevolutionary changes in mandible shape which are attributed to dietary differences (Boell and Tautz 2011;Renaud et al 2013). Babiker and Tautz (2015) studied the insular house mice on Heligoland, a small island in the North Sea off of the north-western coast of Germany.…”