30.10.2023: Male house mice produce complex ultrasonic vocalisations (USVs), especially during courtship and mating. Their calls are similar to birdsong, although they are inaudible to us because they are above the frequency range of human hearing (>20 kHz). Male courtship songs are attractive to females, but it depends on their social experience, as shown in a recent study conducted by Vetmeduni’s Konrad Lorenz Institute of Ethology.
In their study, the researchers conducted a playback experiment with wild female house mice (Mus musculus musculus) in which each subject was simultaneously presented with entering an area with recordings of male USVs versus another area playing a control recording with no male USVs. allowed to choose between an area with a speaker playing
The experiment aimed to test whether the females’ attraction to male USVs was influenced by any of the three factors, social experience (comparing females housed individually or socially with another female), sexual receptivity (comparing females were in oestrus or not), or neonatal paternal exposure (comparing females that were reared with or without their father). Previous studies suggested that these factors influence the attraction of female mice to male USVs, but the results were contrary to expectations and limited to inbred strains of laboratory mice.
Social experience has a positive effect, paternal exposure does not play a role
Overall, the females showed no attraction to the males' USVs, but it turned out to depend upon their housing. "We found that the females were attracted to male USVs if they were housed with another female, whereas females that were housed individually, showed the opposite response and avoided the male USVs,” says Sarah Zala from the Konrad Lorenz Institute for Ethology. "It is unclear why individual housing reversed females' attraction towards male courtship songs", she explains, "but living alone might make them more cautious about approaching an unfamiliar male."
“We also found that females showed more attraction towards male USVs when they were not in oestrus, and especially if they were not in oestrus and socially housed,” says co-author, Dustin Penn also from the Konrad Lorenz Institute for Ethology. "This oestrous effect is consistent with a previous study on laboratory mice, he points out, "but we have no explanation." Finally, early exposure to a father had no effect on the females’ preference for male USVs.
Social experience and sexual cycle make all the difference
In summary, this recent study shows that the attraction of wild female mice towards male courtship songs depended upon their social experience (housing) and oestrous stage. These results should facilitate research on the genetic control of hearing loss, often conducted with laboratory mice. The researchers emphasize how their findings show how seemingly unimportant factors, such as social housing and sexual cycle, can influence the behaviour of mice, despite that these and many other such variables are not usually reported in scientific papers. These results thus raise concerns that unreported variables potentially contribute to the "replication crisis" in science.
The article “Attraction of female house mice to male ultrasonic courtship vocalizations depends on their social experience and estrous stage” by Jakob Beck, Bettina Wernisch, Teresa Klaus, Dustin J. Penn and Sarah M. Zala was published in PLOS ONE.