Poster 30
Presenter: Lauren Brooks
Thursday, 4:00 – 6:00pm

Sources of Natural Selection on Body Size in Island Populations of Wild Mice

Lauren Brooks and Bret A. Payseur
Laboratory of Genetics University of Wisconsin - Madison

House mice (Mus musculus) have a virtually cosmopolitan distribution across the planet. Because of their commensal relationship with humans, they have inadvertently been introduced to both human inhabited and uninhabited islands. This wide distribution of mice on islands with variable biotic and abiotic environments creates a valuable resource to understand how natural selection shapes phenotypic variation. The “Island Rule” states that small mammals will grow larger body sizes on islands whereas large mammals will grow smaller. As mouse body size is a canonical complex genetic trait, it is of interest to examine potential determinants of this trend within house mice. In this investigation, we compare published body masses for island house mice to a series of environmental factors, including geographic location, island area, island perimeter, temperature, precipitation, solar power, human population, number of predators (mammal and avian), and number of competitors. Regression analyses identify multiple biotic and abiotic variables that collectively explain a substantial percentage of the variance in body mass. We compare body mass variation in island mice to that observed across laboratory strains to place our findings in the context of mouse genetics. This research highlights the power of wild house mouse populations for understanding the evolution of biomedically relevant phenotypes.