Abstract:
It is not clear why some species are able to naturalize and spread in a new region while so many other species
are not. Several general properties have been reported for successful non-indigenous plant species (NIPS). These include
presence of a lag time and population expansion following invasion, arrival from a similar climate, ability to self-fertilize,
a short lifespan, clonal growth (if perennial), and production of small fruits. We examined these patterns in comparisons of
all recorded abundant and rare NIPS in Ontario (n = 1153). We used cross-species and phylogenetic regressions to examine
ecological patterns across present-day species and to determine whether evolutionary divergences in NIPS success have been
correlated consistently with divergences in any of the life-history traits, We found a significant time lag in invader spread,
with species arriving after 1952 being more likely to be rare. Successful invaders (i.e .. abundant NIPS) were significantly
over-represented among species originating in Europe and Eurasia. Successful invaders were significantly more likely to demonstrate
clonal growth, to grow on variable soil moistures, and to have comparatively long flowering periods. While analyses such as
this do not reveal causal mechanisms for the observed patterns, our correlative findings suggest important mechanisms for
NIPS success that we discuss in light of the theoretical expectations of the attributes of successful plant invaders.
