Many studies have identified compounds, often called 'pheromones', which influence sexual behavior and physiology in laboratory mice under laboratory conditions. It is widely assumed that these compounds influence reproductive success, and yet surprisingly, this assumption has never been tested in mice or any other mammal. To investigate this hypothesis, a study was recently conducted by Dustin Penn and Sarah Zala and their students at the Konrad Lorenz Institute of Ethology, and their collaborator, Jae Kwak, a chemist who has special technical expertise with pheromones.
They aimed to test whether the pheromones previously identified in studies on laboratory mice actually influence the reproductive success of wild house mice. They released wild house mice into large enclosures where they competed for territories and mates. For 16 weeks, they observed the behavior of the mice, collected urine samples and measured the output of non-volatile and volatile pheromones, and then determined reproductive success using genetic paternity analyses of the offspring.
They found that urinary protein excretion was correlated with male but not female reproductive success. This result explains why male mice produce 3 to 4 times more urinary protein than females. To their surprise, only one volatile pheromone was positively correlated with the number of offspring sired by males. Another compound, trimethylamine or TMA, was negatively correlated with male reproductive success. According to Dr. Penn, TMA smells like rotten fish or dead and decaying animals to the human nose, and it is used an indicator of spoilage. He explains that other studies have found that mice are attracted to normal levels of TMA in the urine, but they are aversive to high concentrations. Interestingly TMA has been found to be elevated in the urine of infected mice. The lead author on the paper, Ken Luzynski, who recently defended his dissertation at the Vetmed Uni, points out that several of their findings are novel, and although they are correlative, some are consistent with results of experimental studies.
The article "Pheromones that correlate with reproductive success in competition conditions" by Kenneth C. Luzynski, Doris Nicolakis, Maria Adelaide Marconi, Sarah M. Zala, Jae Kwak, and Dustin J. Penn was published in Scientific Reports.