Seed viability in relation to pollinator availability in Banksia baxteri

Abstract

Seed set was examined in relation to access to inflorescences by large or small invertebrates, vertebrates, all animal visitors or none. Seed predation by insects was substantial (35–46%) and unrelated to pollinator access. The fewer the categories of animals allowed access to flowers, the greater the proportion of unpredated seeds that were aborted. Germination rates (83–96%) of filled seeds were unrelated to pollinator access, as were survival and size of seedlings at 4 months old. Overall, only 16% of seeds initiated by selfing after exclusion of all pollen vectors resulted in 4-month-old seedlings, compared with 33% of seeds initiated after access by all or larger animal visitors. Pollen and resource limitation are likely to account for only some of these findings. Rather, we suggest that preferential development of progeny fertilised by outcross pollen from other, especially distant, individuals may also play a role in reducing seed formation.