Variation for male success in Holm oak, a monoecious and a highly self-incompatible species

In natural populations, male success is determined by pre-and post-pollination events. The latter could be separated to pre-and post-fertilization stages at which different mechanisms control pollen donor success. It is currently assumed that there is a direct relationship between pollen tube growth rapidity and fertilization ability. In this study, pollination experiments were conducted on a Helm oak (Quercus ilex) population to test male success. Pollen was used in two ways (1) as a single source and (2) mixed with the self pollen of the recipient. We analyzed differences between pollen donors at the prezygotic level by evaluating the relative proportions of the pollen tube presence in the style in comparison to those on the stigma and likewise between the style and the ovary, on five different dates after pollination. At the post-zygotic level, male success was measured as the proportion of fertilized ovules relative to pollinated flowers and as seed sired relative to fertilized ovules. At the pre-and post-zygotic level there were statistically significant differences between recipients that are however not significant between donors. In Quercus species pollination occurs before the ovules develop; our results indicate that different arrangements between pollen tube growth and ovule development may occur. Self-incompatibility may be one factor in differential recipient success through the interactions between out and self-incompatible pollen.