For many Australian plants little is known about either their population genetics or the effects on mating systems of variation in pollen transfer distances. Forrest et al. manipulate pollination of Grevillea mucronulata to allow assessment of the reproductive success of crosses made within and among populations at varying distances and find evidence of both inbreeding and outbreeding depression. Pollen from populations at intermediate distances consistently produces superior outcomes for most aspects of fitness. Natural matings may currently be suboptimal and involve largely near-pollen transfer.
