Population genetics and invasion history of the European Starling across Aotearoa New Zealand

The expansion of human settlements over the past few centuries is
responsible for an unprecedented number of invasive species introductions
globally. An important component of biological invasion management is
understanding how introduction history and post-introduction processes
have jointly shaped present-day distributions and patterns of population
structure, diversity, and adaptation. One example of a successful invader
is the European starling (Sturnus vulgaris), which was intentionally
introduced to numerous countries in the 19th century, including Aotearoa
New Zealand, where it has become firmly established. We used
reduced-representation sequencing to characterise the genetic population
structure of the European starling in New Zealand, and compared the
population structure to that present in sampling locations in the native
range and invasive Australian range. We found that population structure
and genetic diversity patterns suggested restricted gene flow from the
majority of New Zealand to the northmost sampling location (Auckland). We
also profiled genetic bottlenecks and shared outlier genomic regions,
which supported historical accounts of translocations between both
Australian subpopulations and New Zealand, and provided evidence of which
documented translocation events were more likely to have been successful.
Using these results as well as historic demographic patterns, we
demonstrate how genomic analysis complements even well-documented invasion
histories to better understand invasion processes, with direct implication
for understanding contemporary gene flow and informing invasion
management.