Ventro-Ventral Copulation in a Rodent: A Female Initiative?

Abstract

This study reports a high rate of ventro-ventral (VV) copulation in 2 species of the African four-striped mouse- Rhabdomys-and explores its causes. VV postures were observed in 67% encounters with mating attempts, in both species and during intra- and interspecific trials, although discrimination between the species occurred (i.e., duration of sexual behavior or social investigation varied between intra- and interspecies encounters). Striped mice displayed more investigatory behavior during encounters with VV coitus postures than during encounters without mating attempts or with only dorso-ventral postures. Furthermore, mating solicitation was greater in females than in males exclusively when VV coitus occurred, suggesting that females' initiative could explain the high rate of VV postures in our model organism. We propose different hypotheses among which the role of pleasure through its supposed direct and indirect adaptive implications in triggering female initiative.