Temporal variation in gender in an annual plant

Sex allocation can vary widely among flowers on a plant and among plants within a population. Austen and Weis develop a numerical model and use it to demonstrate that the widespread tendency towards declining fruit set from first to last flowers on plants may contribute to temporal variation in allocation optima. Temporal trends in relative pollen and ovule investment measured in Brassica rapa, however, do not match the predicted trends in functional gender, but some findings of the model, namely decreasing male reproductive success with later flowering onset, may nonetheless apply in this taxon.