Specialised plants need not necessarily find the exact same pollinator species in the novel range as pollinators are often functionally equivalent from the plant’s point of view. Nicotiana glauca is specialised for hummingbird pollination in Argentina but has recruited sunbirds to pollinate it in South Africa (photo E). Hummingbirds and sunbirds both belong to a functional group of specialist nectar feeding bird pollinators. Similar examples exist for other pollinator functional groups. Stapelia gigantea, native to South Africa where it is pollinated by carrion flies (photo A), is invasive in Venezuela by virtue of pollination by indigenous carrion flies (photo B, taken in Cerro Seroche National Park, Venezuela); Gomphocarpus physocarpus is pollinated by paper wasps (Vespidae) in its native range in South Africa (photo C) and in Australia where it is invasive (Photo D) and the buzz-pollinated Senna didymobotrya from West Africa is pollinated by carpenter bees (Xylocopa, Apidae) in South Africa (photo F). Photo credits: A, C, & F by SD Johnson, B by I. Herrera, D by M. Ward and E by S. Geerts.
It’s an old idea that plants that are specialised for particular pollinators should become invasive less often than those which can be pollinated by a broad range of animal species. Most plant species will not encounter their original pollinators when introduced elsewhere so to reproduce in their novel range they will have to recruit novel pollinators.
