Data from: Retracing the routes of introduction of invasive species: the case of the Sirex noctilio woodwasp.

Understanding the evolutionary histories of invasive species is critical
to adopt appropriate management strategies, but this process can be
exceedingly complex to unravel. As illustrated in this study of the
worldwide invasion of the woodwasp Sirex noctilio, population genetic
analyses using coalescent-based scenario testing together with Bayesian
clustering and historical records provide opportunities to address this
problem. The pest spread from its native Eurasian range to the Southern
Hemisphere in the 1900’s and recently to Northern America, where it poses
economic and potentially ecological threats to planted and native Pinus
spp. To investigate the origins and pathways of invasion, samples from
five continents were analysed using microsatellites and sequence data.
Surprisingly, clustering analyses revealed two gene pools. Scenario
testing showed independent introductions from an unsampled source,
putative source of the second gene pool. The invasion history was much
more complex than previously believed, with most of the populations being
admixtures resulting from independent introductions from Europe and
subsequent spread among the invaded areas. Results also shed light on the
micro-evolutionary processes occurring during introductions, and showed
that only few specimens gave rise to some of the populations. Analyses of
microsatellites using clustering and scenario testing considered against
historical data drastically altered our understanding of the invasion
history of S. noctilio and will have important implications for the
strategies employed to fight its spread. This study illustrates the value
of combining clustering and ABC methods in a comprehensive framework to
dissect the complex patterns of spread of global invaders.