Lead researcher Dustin Penn from Vetmeduni Vienna discovered that male house mice attract female house mice better because the former excretes higher pheromone levels compared to other male mice.
Pheromones are substances secreted usually by male species that change the behavior of female species, especially through sexual arousal. Male house mice show ownership of their territories through secretion of urine. Urine contains different kinds of pheromones. These scientists show that excretion of major urinary proteins (MUPs) double when male mice demonstrate ownership and acquire social prominence. The release of volatile pheromones is stabilized and bound by MUPs. "We also conducted olfactory tests and found that sexually receptive female mice were more attracted by the scent of dominant than subordinate males, whereas non-receptive females did not show this olfactory preference," Penn reiterates.
Analysis of "attracting" compounds
The findings of this study were published in Nature that showed which compounds control female attraction. The pheromone MUP20 (darcin) had a significant increase in dominant males. "Our findings show that once male house mice become territorial and socially dominant, they upregulate the amount and types of excreted MUPs, which increases the intensities of volatiles and the attractiveness of their urinary scent to sexually receptive females," says Penn.
Moreover, this study is novel in demonstrating that the production of pheromones is upregulated in dominant, territorial males. "This finding is a fascinating example of how changes in social behavior can affect gene expression. The present results are of enormous interest for behavioral biologists, especially with regard to chemosensory communication," says Penn.
What are the functions of MUPs?
One of the roles of the MUPs is attracting females. One of these pheromones MUP20, which is named as darcin, is coined after Pride and Prejudice's main character Mr. Darcy. Socially dominant males are favored by female mice. The researchers hypothesized and further concluded that MUPs are regulated by males in order to show their dominance and attract the female species. It is currently known that human species do not release MUPs as the sole MUP gene is non-functional.
