Data from: Spatial population genetic structure of a bacterial parasite in close coevolution with its host

Knowledge of a species’ population genetic structure can provide insight
into fundamental ecological and evolutionary processes including gene
flow, genetic drift, and adaptive evolution. Such inference is of
particular importance for parasites, as an understanding of their
population structure can illuminate epidemiological and coevolutionary
dynamics. Here we describe the population genetic structure of the
bacterium Pasteuria ramosa, a parasite that infects planktonic crustaceans
of the genus Daphnia. This system has become a model for investigations of
host-parasite interactions and represents an example of coevolution via
negative frequency-dependent selection (a.k.a. ‘Red Queen’ dynamics). To
sample P. ramosa, we experimentally infected a panel of Daphnia hosts with
natural spore banks from the sediments of 25 ponds throughout much of the
species range in Europe and Western Asia. Using 12 polymorphic VNTR loci,
we identified substantial genetic diversity both within and among
localities that was structured geographically among ponds. Genetic
diversity was also structured among host genotypes within ponds, though
this pattern varied by locality, with P. ramosa at some localities
partitioned into distinct host-specific lineages, and other localities
where recombination had shuffled genetic variation among different
infection phenotypes. Across the sample range, there was a pattern of
isolation-by-distance, and principal components analysis coupled with
Procrustes rotation identified congruence between patterns of genetic
variation and geography. Our findings support the hypothesis that
Pasteuria is an endemic parasite coevolving closely with its host. These
results provide important context for previous studies of this model
system and inform hypotheses for future research.