<p>This thesis addressed phenotypic and genetic variation in seasonal time keeping mechanisms of the tundra vole (<i>Microtus oeconomus</i>) and the common vole (<i>Microtus arvalis</i>). Voles (<i>Microtus</i>) are short-lived, non-hibernating and seasonally breeding rodents. The genus has rapidly evolved (< 2 million years) into one of the most speciose mammalian genera (Sitnikova et al. 2007; ...