Fitness consequences of female alternative reproductive tactics in house mice (Mus musculus domesticus)

Alternative reproductive tactics are defined as discrete differences in morphological, physiological and/or behavioral traits associated with reproduction, which occur within the same sex and population. House mice provide a rare example for alternative reproductive tactics in females, which can either rear their young solitarily, or together with one or several other females in a communal nest. We assessed the fitness consequences of communal and solitary breeding in a wild population to understand how the two tactics can be evolutionarily stable. Females switched between the two tactics (with more than 50% of all females having two or more litters using both tactics), pointing towards communal and solitary breeding being two tactics within a single strategy and not two genetically determined strategies. Communal breeding resulted in reduced pup survival and negatively impacted female reproductive success. Older and likely heavier females more often reared their litters solitarily, ind...