Mating and fitness consequences of variation in male allocation in a wind pollinated plant

In hermaphrodites, the allocation of resources to each sex function can influence fitness through mating success. A prediction that arises from sex allocation theory is that in wind-pollinated plants, male fitness should increase linearly with investment of resources into male function but there have been few empirical tests of this prediction. In a field experiment we experimentally manipulated allocation to male function in Ambrosia artemisiifolia (common ragweed) and measured mating success in contrasting phenotypes using genetic markers. We investigated the effects of morphological traits and flowering phenology on male siring success, and on the diversity of mates. Our results provide evidence for a linear relation between allocation to male function, mating and fitness. We find earlier onset of male flowering time increases reproductive success, whereas later flowering increases the probability of mating with diverse individuals. Our study is among the first empirical studies testing the prediction of linear male fitness returns in wind pollinated plants and emphasize the importance of a large investment into male function by wind pollinated plants and mating consequences of temporal variation in sex allocation. 

Methods
The dataset contains phenoytpic data for Ambrosia artemisiifolia (ragweed) plants grown in a common garden field array. For a subset of 60 plants, twenty seeds were genotyped with microsatellite markers. The paternity of seeds was assessed, so that for each plant in the field there is data on the number of seeds it sired, the number of different mates on which it sired seeds. For the focal females, there is data on the number of different males that sired the seeds.