The fraction of pollen that is carried over from one flower to the next as a pollinator visits a sequence of flowers has a strong effect on patterns or mating in plant populations. Although most studies have used simple exponential or geometric functions to represent carryover, pollen deposition patterns often show longer-than-geometrics tails, suggesting a systematic increase in the carryover fraction. We introduce a changing carryover model that allows the carryover fraction to increase or decrease during a sequence of visits (...)