Seasonal variations in the effectiveness of urinary chemosignals influencing puberty in female house mice.

Three separate experiments tested whether the seasonal variation in the effectiveness for accelerating or delaying puberty in female conspecifics of male urine, urine from pregnant or lactating females, and urine from females housed in groups is attributable to seasonal changes in the quality of the chemosignals released by the donor mice or to seasonal shifts in the sensitivity to the chemosignals for recipient females or to some interaction between these two factors. Six-by-six cross-classified designs were used with urine collection taking place in alternate months for 1 year and urine treatments with samples from all 6 collection months applied in the same alternate months in the subsequent year. For all three urinary chemosignals the seasonal variations in chemosignal effectiveness were determined to be a function of changes in recipient sensitivity and not of any seasonal shifts in the chemosignals released by donor mice. Seasonal variations in body weight at weaning were also a contributory factor in determining the age of first vaginal oestrus. Covariance analyses revealed that, even after adjustment of the treatment means for the seasonal differences in body weight, there were significant effects on the age of puberty due to seasonal shifts in recipient sensitivity, but not with respect to the month in which the urine was collected.