Genetic variation in maternal yolk testosterone allocation predicts female mating decisions in Japanese quail

Maternal reproductive effort can be adjusted through the transfer of hormones into the eggs, where they influence embryo development, mediating short- and long-term maternal effects on offspring phenotype. While studies usually explore how females can increase their reproductive success through an allocation of yolk testosterone (T) under external environmental variability, it is less clear whether intrinsically driven interfemale differences in yolk T deposition may themselves predict female reproductive decisions. In our study, we used Japanese quail, Coturnix japonica, lines divergently selected for high (HET) and low (LET) egg T concentrations to examine whether this genetic variation in yolk T levels is linked to female mating decisions. First, we analysed line differences in male-typical reproductive behaviour and how this behavioural response is affected by female line identity. Males were tested with females from the same (match pairs) and opposite (cross pairs) lines. Next, female mate preferences were evaluated in a two-choice test in which females were allowed to choose between males from the same and opposite lines. We found no line differences in male copulatory behaviour. Interestingly, a shorter latency to copulate and a higher number of copulations were recorded in LET males when they were mated with HET than LET females. No differences between match and cross pairs were found in HET males. In the two-choice test, LET females displayed a preference for males from the same over the opposite line, but HET females did not discriminate between LET and HET males. Collectively, these results demonstrate that genetically high yolk T deposition is related to higher receptivity and reduced choosiness in female mate preferences in Japanese quail. Moreover, our results indicate an important link between maternal investment, reproductive physiology and female mating decisions, pointing out evolutionary implications and a role of variation in female mate choice in sexual selection.