title: The importance of pollinators and autonomous self-fertilisation in the early stages of plant invasions: Banksia and Hakea (Proteaceae) as case studies.
abstract: Reproduction is a crucial stage in the naturalisation of introduced plant species. Here, using breeding system experiments and observations of floral visitors, we investigate whether a lack of pollinators or an inability to autonomously self-fertilise limits naturalisation in five Australian Banksia species and the co-familial Hakea salicifolia in South Africa. Banksia species were heavily utilised by native insects and nectar-feeding birds. Although Banksia produced fruit when pollinators were excluded, pollinators significantly increased seed set in four of the five species. H. salicifolia flowers were visited by 11 insect species; honeybees (Apis mellifera) were the main visitors. Flowers in naturalised H. salicifolia populations received almost four times the number of visits as flowers in non-naturalised populations; the latter showed both pollen limitation (PLI 0.40) and partial self-incompatibility. This should not prevent invasion, since H. salicifolia produces fruits via autonomous selfing in the absence of pollinators. The results suggest a limited role of breeding systems in mediating naturalisation of introduced Proteaceae species. Other factors, such as features of the recipient environments, appear to be more important. Spatial variation in rates of reproduction might, however, explain variation in the extent and rate of naturalisation of different populations.
authors: Department of Botany and Zoology, Centre for Invasion Biology, Stellenbosch University, Matieland, South Africa.|Invasive Species Programme, South African National Biodiversity Institute, Kirstenbosch National Botanical Gardens, Claremont, South Africa.|School of Agriculture, Earth and Environmental Science, University of KwaZulu-Natal, Durban, South Africa.
authors: D
authors: D
authors: Moodley
authors: Department of Botany and Zoology, Centre for Invasion Biology, Stellenbosch University, Matieland, South Africa.|Invasive Species Programme, South African National Biodiversity Institute, Kirstenbosch National Botanical Gardens, Claremont, South Africa.|Department of Conservation and Marine Sciences, Cape Peninsula University of Technology, Cape Town, South Africa.
authors: S
authors: S
authors: Geerts
authors: Department of Botany and Zoology, Centre for Invasion Biology, Stellenbosch University, Matieland, South Africa.
authors: D M
authors: DM
authors: Richardson
authors: Department of Botany and Zoology, Centre for Invasion Biology, Stellenbosch University, Matieland, South Africa.|Invasive Species Programme, South African National Biodiversity Institute, Kirstenbosch National Botanical Gardens, Claremont, South Africa.
authors: J R U
authors: JR
authors: Wilson
mesh_terms: D000818:Animals; D001315:Australia; D001516:Bees; D035264:Flowers / Q000502:physiology; D007313:Insecta; D058865:Introduced Species; D011058:Pollen; D054817:Pollination / Q000502:physiology*; D039105:Proteaceae / Q000502:physiology*; D012639:Seeds / Q000254:growth & development; D057945:Self-Fertilization / Q000502:physiology*; D013019:South Africa
keywords: Biological invasions; Proteaceae; South Africa; breeding system; naturalisation; pollen limitation index