Understanding which species are introduced and become invasive and why are central questions
in invasion science. Comparative studies on model taxa have provided important insights, but
much more needs to be done to unravel the context-dependencies of these findings. The cactus
family (Cactaceae), one of the most popular horticultural plant groups, is an interesting case study.
Hundreds of cactus species have been introduced outside their native ranges; a few of them are
among the most damaging invasive plant species in the world. We reviewed the drivers of
introductions and invasions in the family and seek insights that can be used to minimise future
risks. We compiled a list of species in the family and determined which have been recorded as
invasive. We also mapped current global distributions and modelled the potential global distributions based on bioclimatic data of known invasive taxa. Finally, we identified whether
invasiveness is phylogenetically clustered for cacti and whether particular traits are correlated with
invasiveness. Only 57 of the 1922 cactus species recognised in this treatment have been recorded
as invasive. There are three invasion hotspots: South Africa (35 invasive species recorded),
Australia (26 species), and Spain (24 species). However, there are large areas of the world with
climates suitable for cacti that are at risk of future invasion - in particular parts of China, eastern
Asia and central Africa. The invasive taxa represent an interesting subset of the total species pool.
There is a significant phylogenetic signal: invasive species occur in two of the three major
phylogenetic clades, and in 13 of the 130 genera. This phylogenetic signal is not driven by human
preference, i.e. horticultural trade. Moreover, all invasive species are from five of the 12 cactus growth forms. Finally, invasive species tend to have significantly larger native ranges than noninvasive
species, and none of the invasive species are of conservation concern in their native
range. These results suggest fairly robust correlates of invasiveness that can be used for proactive
management and risk assessments.
Walker, Gareth A.; Robertson, Mark P.; Gaertner, Mirijam; Gallien, Laure; Richardson, David M.(Springer, 2017-12)
Invasive trees are a major problem in South Africa. Many species are well established whereas others are still in the early stages of invasion. The management of invasive species is most cost effective at the early stages ...
Rouget, Mathieu; Robertson, Mark P.; Wilson, John R.U; Hui, Cang; Essl, Franz; Renteria, Jorge; Richardson, David M.(Wiley, 2016-04)
AIM : We develop a framework for quantifying invasions based on lagged trends in invasions
(―invasion debt‖) with the aim of identifying appropriate metrics to quantify delayed
responses at different invasion stages — ...
Faulkner, Katelyn T.; Robertson, Mark P.; Rouget, Mathieu; Wilson, John R.U.(Elsevier, 2014-11)
Biosecurity schemes aim to prevent the introduction of species with a high invasion
potential, without unduly restricting personal freedom and commercial activities. But
invasive species risk assessments are time consuming, ...