Sexual Dimorphism of the Protein Level in Urine of Muridae Rodents: Relation to Population Numbers

The results of a comparative study conducted on the water vole, steppe lemming, and Campbell hamster, fulfilled by data published on seven other Muridae rodent species, have revealed a positive relation between the extent of sexual dimorphism estimated by the protein level in urine and population numbers typical for each species and the amplitude of its variation. In species with usually low population numbers, the ratio of protein in urine of males to females comprises 0.9; in species with relative stable population numbers, it is 3.4; and, in species with a high amplitude of periodically fluctuating population numbers, it is 8.3.