Alternative dispersal phenotypes in house mice

Different behavioural and life-history strategies can be adaptive within a particular environment, allowing multiple individual strategies to be maintained. This can be important for a species’ ability to adapt to changes in selection pressures. The behavioral and genetic mechanisms responsible for maintaining such variation are, however, poorly understood. I aim to investigate the evolution, maintenance and proximate mechanisms of alternative adaptations within populations. To do so, I will make use of a genetically based difference in emigration propensity (high/low departure from the home population) in wild-derived house mice (Mus musculus domesticus), associated with the t haplotype, a naturally occurring supergene that causes transmission bias, or gene “drive”. Increased departure from the home population and increased longevity are associated with the t haplotype local to the Zurich area (Manser et al. 2011; Runge and Lindholm 2018). This phenotype therefore provides an excellent opportunity to analyze the evolution of integrated suites of traits within a population. This study will test current ideas of behavioural, dispersal, and pace-of-life syndromes using replicated experiments with wild-derived animals. It will allow analysis of the effect of group composition on social behaviour and fitness outcomes, which is critical for understanding divergence in social traits. It will provide a unique study of the effects of a selfish genetic element in an ecological context, which is relevant to conservation efforts and developments of artificial gene drive systems. Finally, fitness analyses of a swath of costly traits will help to understand their costs and benefits and evolution. Overall, this study will provide an intensive and rare contribution to understanding the evolution of alternative dispersal phenotypes in a wild mammal.