Experimental evidence for pollination of Banksia spp. by non-flying mammals
The importance of non-flying mammals as pollinators of Banksia integrifolia and B. spinulosa was analysed by examining the effect of pollinator exclusions on fruit-set. Visitation by potential pollinators was also measured by observation and by indirect methods. Nonflying mammals were frequent visitors to inflorescences of both Banksia species. The aluminium sleeves used to exclude non-flying mammals from B. integrifolia trees were associated with a reduction in both the number of infructescences produced and the number of fruit per infructescence, indicating that non-flying mammals were important pollinators. Bird-nets over trees also significantly reduced the number of fruit per infructescence, but had no significant effect on the number of infructescences produced. The results of exclusion experiments using single inflorescences were inconclusive due to low fruitset. No conclusions could be drawn from these experiments with B. spinulosa. However, results for B. integrifolia support the conclusions of whole-tree experiments. Analysis of the genotype frequencies in seed from B. integrifolia provided no support for the hypothesis that the relatively limited mobility of non-flying mammal pollinators would cause inbreeding.