Data from: Why close relatives make bad neighbors: phylogenetic conservatism in niche preferences and dispersal disproves Darwin’s Naturalization Hypothesis in the thistle tribe

The number of exotic plant species that have been introduced into the
United States far exceeds that of other groups of organisms, and many of
these have become invasive. As in many regions of the globe, invasive
members of the thistle tribe, Cardueae, are highly problematic in the
California Floristic Province, an established biodiversity hotspot. While
Darwin's naturalization hypothesis posits that plant invaders closely
related to native species would be at a disadvantage, evidence has been
found that introduced thistles more closely related to native species are
more likely to become invasive. To elucidate the mechanisms behind this
pattern, we modelled the ecological niches of thistle species present in
the province and compared niche similarity between taxa and their
evolutionary relatedness, using fossil-calibrated molecular phylogenies of
the tribe. The predicted niches of invasive species were found to have
higher degrees of overlap with native species than noninvasive introduced
species do, and pairwise niche distance was significantly correlated with
phylogenetic distance, suggesting phylogenetic niche conservatism.
Invasive thistles also displayed superior dispersal capabilities compared
to noninvasive introduced species, and these capabilities exhibited a
phylogenetic signal. By analysing the modelled ecological niches and
dispersal capabilities of over a hundred thistle species, we demonstrate
that exapted preferences to the invaded environment may explain why close
exotic relatives may make bad neighbours in the thistle tribe.