Sex pheromone levels are associated with paternity rate in brown rats

Abstract

Abstract: In muroid rodents, urine-borne volatile compounds and major urinary proteins (MUPs) constitute the key male pheromones that shape the sexual attractiveness of males. Here, we aimed to examine whether male pheromone levels were related to sexual attractiveness and reproductive success in the North China subspecies of the brown rat (Rattus norvegicus humiliatus). According to the abundance of 2-heptanone (2H), the predominant male pheromone in male urine, male rats were first categorized into a high-2H group and a low-2H group. The levels of the whole volatile profile and non-volatile MUPs were found to be higher in the high-2H group than in the low-2H group. Moreover, the abundances of urinary volatile pheromones or pheromone candidates were positively correlated with the abundance of total MUPs. Two-way choice tests revealed that male urine from the high-2H group was more attractive to females than that from the low-2H group. Microsatellite loci analysis of paternal lineage revealed that the females had single-paternity offspring and that the high-2H group sired more offspring and had higher rates of paternity than did the low-2H group. These results suggest that urine-borne volatile pheromones alone or together with MUP pheromones can predict sexual attractiveness and reproductive success in male rats. Significance statement: Sexual attractiveness can be quantified using volatile and MUP pheromones and their candidates in deposited urine. 2-Heptanone (a major pheromone) and other urine-borne volatile pheromones or their candidates and total MUPs showed the same difference patterns in males and predicted male sexual attractiveness. The abundances of volatile pheromones or their candidates and total MUPs were associated with reproductive success and paternity rate in males.