Behavioural, morphological, and life history shifts during invasive spread

Invasive species are common around the world, but we still do not know
which traits are most important for successfully establishing in new
environments. Different stages of the invasion process, including
transport, introduction, establishment, and spread, can act as selective
filters for different combinations of phenotypic traits. Theoretical and
empirical studies predict that invasive populations should have suites of
behaviours that improve dispersal and spread, including higher boldness,
dispersal propensity, and activity levels than native populations. In this
study, we tested these predictions by comparing the morphology, life
history, and behaviour of an invasive populations of redback spiders,
Latrodectus hasselti, from Japan to a population of native spiders from
Australia, with additional comparisons of another invasive population from
New Zealand. We found that both a longer-established invasive New Zealand
population and the more recently-established invasive Japanese population
were more dispersive than the native Australian population. The Japanese
invasive population showed elevated levels of sibling cannibalism relative
to the native population, which may increase total reproductive success of
females under food limitation. Japanese spiders were also less bold in
response to a simulated predator threat compared to the native Australian
population. In contrast to the prediction that invasive populations would
show uniformly fast life history traits, the invasive Japanese population
was more fecund, yet took longer to develop than the native population
under laboratory conditions. Overall, our results show that invasive
populations are phenotypically distinct from native populations, with some
behavioural, life history, and morphological traits that would increase
spread (dispersal tendency, high fecundity) and persistence (sibling
cannibalism) in new habitats.