Promiscuous pollination of Australia’s baobab, the boab, Adansonia gregorii

Abstract

Australia’s native baobab, Adansonia gregorii (F.Muell., Malvaceae: Bombacoideae) is the only baobab outside the African continent. Baobabs of the African continent have shades either of red, orange and yellow coloured flowers and are pollinated by insects, especially by hawkmoths of the Sphingidae family, or have white flowers and are pollinated by small mammals (e.g. bats and lemurs). In contrast, the Australian baobab, with white, erected flowers, was found to be mostly pollinated by hawkmoths. It is possible that for this white-flowered species, small mammals play a role in pollination. Therefore, the aim of the study was to identify major pollinators of the Australian baobab. Motion cameras were used in December 2013 and ground observations were performed in the flowering season of 2015–2016 to observe (potential) pollinators. Results show observations of hawkmoths and other insects, birds and sugar gliders (Petaurus breviceps) pollinating the flowers. The major pollinator found in this study was, however, the black flying fox (Pteropus alecto): it was observed foraging in groups and consuming the anthers of the Australian baobab flowers. Pollination by megabats, as the black flying fox, could have played an important role in the evolution of the white, erect flower of Australian baobabs.