Reproductive isolation of co-occurring Banksia species at the Yule Brook Botany Reserve, Western Australia

Abstract

Mechanisms assisting the maintenance of genetic identity of four species of Banksia (B. attenuata, B. menziesii, B, littoralis and B. telmatiaea) occurring in close proximity are reported. The summer-flowering B. attenuata was phenologically isolated from the other co-occurring species. Of the winter-flowering species B. menziesii, in addition to inhabiting a slightly more elevated, drier habitat in the reserve, showed pollen-style incompatibility with both B. littoralis and B. telmatiaea. B. littoralis and B. telmatiaea appear to be potentially hybridized as they share the same lowland habitat, flowering period, and a few common pollinators, and artificial interspecific pollen germination was achieved. It is suggested, however, that these two species may be adapted morphologically and physiologically to the attraction of different animal pollinators although it is more likely that the Banksia species maintain genetic identity through behavioural constancy of individuals of those animal species.