Data from: Colonization history, host distribution, anthropogenic influence and landscape features shape populations of white pine blister rust, an invasive alien tree pathogen

White pine blister rust is caused by the fungal pathogen Cronartium
ribicola J.C. Fisch (Basidiomycota, Pucciniales). This invasive alien
pathogen was introduced into North America at the beginning of the 20th
century on pine seedlings imported from Europe and has caused serious
economic and ecological impacts. In this study, we applied a population
and landscape genetics approach to understand the patterns of introduction
and colonization as well as population structure and migration of C.
ribicola. We characterized 1,292 samples of C. ribicola from 66 geographic
locations in North America using single nucleotide polymorphisms (SNPs)
and evaluated the effect of landscape features, host distribution, and
colonization history on the structure of these pathogen populations. We
identified eastern and western genetic populations in North America that
are strongly differentiated. Genetic diversity is two to five times higher
in eastern populations than in western ones, which can be explained by the
repeated accidental introductions of the pathogen into northeastern North
America compared with a single documented introduction into western North
America. These distinct genetic populations are maintained by a barrier to
gene flow that corresponds to a region where host connectivity is
interrupted. Furthermore, additional cryptic spatial differentiation was
identified in western populations. This differentiation corresponds to
landscape features, such as mountain ranges, and also to host
connectivity. We also detected genetic differentiation between the
pathogen populations in natural stands and plantations, an indication that
anthropogenic movement of this pathogen still takes place. These results
highlight the importance of monitoring this invasive alien tree pathogen
to prevent admixture of eastern and western populations where different
pathogen races occur.