Data from: Population genomic analyses reveal a history of range expansion and trait evolution across the native and invaded range of yellow starthistle (Centaurea solstitialis)

Identifying sources of genetic variation and reconstructing invasion
routes for non-native introduced species is central to understanding the
circumstances under which they may evolve increased invasiveness. In this
study, we used genome-wide single nucleotide polymorphisms to study the
colonization history of Centaurea solstitialis in its native range in
Eurasia and invasions into the Americas. We leveraged this information to
pinpoint key evolutionary shifts in plant size, a focal trait associated
with invasiveness in this species. Our analyses revealed clear population
genomic structure of potential source populations in Eurasia, including
deep differentiation of a lineage found in the southern Apennine and
Balkan Peninsulas and divergence among populations in Asia, eastern
Europe, and western Europe. We found strongest support for an evolutionary
scenario in which western European populations were derived from an
ancient admixture event between populations from eastern Europe and Asia,
and subsequently served as the main genetic ‘bridgehead’ for introductions
to the Americas. Introductions to California appear to be from a single
source region, and multiple, independent introductions of divergent
genotypes likely occurred into the Pacific Northwest. Plant size has
evolved significantly at three points during range expansion, including a
large size increase in the lineage responsible for the aggressive invasion
of California's interior. These results reveal a long history of
colonization, admixture, and trait evolution in C. solstitialis, and
suggest routes for improving evidence-based management decisions for one
of the most ecologically and economically damaging invasive species in the
western United States.