Flowering plants display considerable variation in mating system, particularly the relative frequency of cross- and self-fertilization. The majority of estimates of outcrossing rate do not account for temporal variation, particularly during the flowering season.
Yin et al. investigate seasonal variation in mating using genetic markers in Incarvillea sinensis (Bignoniaceae), a desert annual with showy, insect-pollinated flowers capable of delayed selfing. They report evidence of mixed mating but with a significant increase in selfing as pollinator visitation declined towards the end of the season. They suggest that delayed selfing provides reproductive assurance when harsh environments limit pollinator service.
Ge Yin, Spencer C. H. Barrett, Yi-Bo Luo, Wei-Ning Bai, 2015, 'Seasonal variation in the mating system of a selfing annual with large floral displays', Annals of Botany, vol. 117, no. 3, pp. 391-400 http://dx.doi.org/10.1093/aob/mcv186