Data from: Invasive cane toads are unique in shape but overlap in ecological niche compared to Australian native frogs

Invasive species are an important issue worldwide but predicting
invasiveness, and the underlying mechanisms that cause it, is difficult.
There are several primary hypotheses to explain invasion success. Two main
hypothesis based on niche spaces stand out as alternative, although not
exclusive. The empty niche hypothesis states that invaders occupy a vacant
niche space in the recipient community, and the niche competition
hypothesis states that invaders overlap with native species in niche
space. Studies on trait similarity/dissimilarity between the invader and
native species can provide information on their niche overlap. Here, we
use the highly invasive and well-studied cane toad (Rhinella marina) to
test these two hypotheses in Australia, and assess its degree of overlap
with native species in several niche dimensions. We compare extensive
morphological and environmental data of this successful invader to 235
species (97%) of native Australian frogs. Our study is the first to
document the significant morphological differences between the invasive
cane toad and a continent-wide frog radiation: despite significant
environmental overlap, cane toads were distinct in body size and shape
from most Australian frog species, suggesting that in addition to their
previously documented phenotypic plasticity and wide environmental and
trophic niche breadth, their unique shape also may have contributed to
their success as an invasive species in Australia. Thus, the invasive
success of cane toads in Australia may be explained through them
successfully colonizing an empty niche among Australian anurans. Our
results support that the cane toad's distinct morphology may have
played a unique role in the invasiveness of this species in Australia,
which coupled with a broad environmental niche breadth, would have boosted
their ability to expand their distribution across Australia. We also
propose RLLR (Relative limb length ratio) as a potentially useful measure
of identifying morphological niche uniqueness and a potential measure of
invasiveness potential in anuran amphibians.