Rank-dependency of major urinary protein excretion in two house mouse subspecies

Abstract

Chemical communication is important for many social mammals. Scent-related gene clusters have undergone extraordinary expansion in some species, such as the house mouse (Mus musculus). One such family encodes major urinary proteins (MUPs). MUPs can provide recipients with complex information about the signaller and potentially serve as honest signals of social rank. In this study, we examined the development of overall MUP production in two mouse subspecies in the context of establishing their social hierarchy during the critical period between weaning and 100 days of age. We used fraternal pairs as simple social units, where dominant/subordinate ranks were naturally established between two brothers raised together, to test the hypothesis that dominant males of both taxa excrete higher amounts of MUPs in their urine than subordinates. The results were compared to data on ontogeny of steroid hormone levels gathered in the same individuals during an earlier experiment. Higher MUP levels in dominant males were only corroborated in one subspecies (domesticus), whereas musculus males revealed similar MUP quantities irrespective of rank. These results are consistent with the notion that these closely related taxa adopted different strategies for establishing social hierarchy.

The Expansion of House Mouse Major Urinary Protein Genes Likely Did Not Facilitate Commensalism with Humans

“…Second, the expression of individual MUPs is regulated by a complex endocrine system involving testosterone, thyroxine, and growth hormone [83,84]. Consequently, can be down-regulated or up-regulated depending on health, food supply, age, and other conditions [85,86], or as a consequence of social interactions [87], although the latter potential influence might have been prevented or at least reduced by individual housing of the mice under study. It has been suggested that uMUPs are able to provide individual identity information in urine markings (e.g., [36,50,53,[88][89][90][91][92]).…”