Pollination ecology of the invasive tree tobacco <i>Nicotiana glauca</i>: comparisons across native and non-native ranges

Abstract

Interactions with pollinators are thought to play a significant role in determining whether plant species become invasive, and ecologically generalised species are predicted to be more likely to invade than more specialised species. Using published and unpublished data we assessed the floral biology and pollination ecology of the South American native Nicotiana glauca (Solanaceae) which has become a significant invasive of semi-arid parts of the world. In regions where specialised bird pollinators are available, for example hummingbirds in California and sunbirds in South Africa and Israel, N. glauca interacts with these local pollinators and sets seed by both out-crossing and selfing. In areas where there are no such birds, such as the Canary Islands and Greece, abundant viable seed is set by selfing, facilitated by the shorter stigma-anther distance compared to plants in native populations. Surprisingly, in these areas without pollinating birds, the considerable nectar resources are only rarely exploited by other flower visitors such as bees or butterflies, either legitimately or by nectar robbing. We conclude that Nicotiana glauca is a successful invasive species outside of its native range, despite its functionally specialised hummingbird pollination system, because it has evolved to become more frequently self pollinating in areas where it is introduced. Its invasion success is not predictable from what is known of its interactions with pollinators in its home range.

Effects of native pollinator specialization, self‐compatibility and flowering duration ofEuropean plant species on their invasiveness elsewhere

“…This indicates that pollinator specialization may not be a huge barrier to becoming invasive, and is in line with some recent case studies showing that apparently specialized plant species can become invasive (Rodger, van Kleunen & Johnson ; Ollerton et al . ). The next step for arriving at a better mechanistic understanding of the role of pollinator generalization in invasiveness would be to test whether pollinator generalization as measured in the native range is positively associated with pollinator generalization in the non‐native range.…”

Plant toxin levels in nectar vary spatially across native and introduced populations

“…; Ollerton et al . ). Invasion theory makes several predictions in relation to the chemical defence of plant root and vegetative structures in introduced species (Callaway & Ridenour ; Joshi & Vrieling ; Cappuccino & Arnason ; Doorduin & Vrieling ).…”

Provincial and cosmopolitan: floristic composition of a dryland urban river

“…Another intriguing question is why some of the riparian-affiliated species widely planted in the Phoenix area, such as Nerium oleander, a tree of Mediterranean streambeds (Salinas and Guirado 2002;Magdaleno 2013) and Nicotiana glauca, a bird-pollinated species now common in dry parts of the world (Ollerton et al 2012), remain sparse along the urban Salt River. Comparisons of regeneration niches, dispersal modes, and other life-history traits will be necessary to determine why certain landscape species are thriving in the river bed while others are not (Silverstein 2005;Osawa et al 2013).…”