Interestingly, when a mixture of the two donors was applied once, all at the same time, simulating delayed stigma receptivity (because all the pollen start to grow toward the ovules at the same time), there was greater offspring diversity compared to two separate pollination events, one from each donor. In other words, the proportion of offspring sired by each donor was more even in the single pollination event of mixed pollen, rather than being dominated by a single donor.
Moreover, high paternal diversity was also associated with increased seed production, indicating a fitness advantage to delaying stigma receptivity.
"Our results indicate that in our study species the ability to enhance pollen competition between competing mates by delaying stigma receptivity is beneficial because it increases paternal diversity of the brood, which in turn is positively connected to number of seeds produced," Lankinen said. "Even though many studies have shown that enhanced pollen competition can be beneficial for the female reproductive function, the underlying reason for this association is not clear."
Given the benefit of delaying stigma receptivity, Lankinen notes that she and her colleagues "are puzzled by the fact that variation in timing of stigma receptivity is very large in wild populations," and concludes that it would be of interest to understand more about this trait under natural conditions.
Of additional interest is the potential occurrence of a sexual conflict over timing of stigma receptivity. "We have detected that some pollen donors can fertilize ovules ahead of others, presumably securing paternity by avoiding competition with later arrivi
|Contact: Richard Hund|
American Journal of Botany