Data from: Temporal sampling helps unravel the genetic structure of naturally occurring populations of a phytoparasitic nematode. 2. Separating the relative effects of gene flow and genetic drift

Studying wild pathogen populations in natural ecosystems offers the
opportunity to better understand the evolutionary dynamics of biotic
diseases in crops and to enhance pest control strategies. We used
simulations and genetic markers to investigate the spatial and temporal
population genetic structure of wild populations of the beet cyst nematode
Heterodera schachtii on a wild host plant species, the sea beet (Beta
vulgaris spp. maritima), the wild ancestor of cultivated beets. Our
analysis of the variation of eight microsatellite loci across four study
sites showed that (i) wild H. schachtii populations displayed fine-scaled
genetic structure with no evidence of substantial levels of gene flow
beyond the scale of the host plant, and comparisons with simulations
indicate that (ii) genetic drift substantially affected the residual
signals of isolation-by-distance processes, leading to departures from
migration-drift equilibrium. In contrast to what can be suspected for
(crop) field populations, this showed that wild cyst nematodes have very
low dispersal capabilities and are strongly disconnected from each other.
Our results provide some key elements for designing pest control
strategies, such as decreasing passive dispersal events to limit the
spread of virulence among field nematode populations.