Data from: The influence of genetic drift and selection on quantitative traits in a plant pathogenic fungus

Genetic drift and selection are ubiquitous evolutionary forces acting to
shape genetic variation in populations. While their relative importance
has been well studied in plants and animals, less is known about their
relative importance in fungal pathogens. Because agro-ecosystems are more
homogeneous environments than natural ecosystems, stabilizing selection
may play a stronger role than genetic drift or diversifying selection in
shaping genetic variation among populations of fungal pathogens in
agro-ecosystems. We tested this hypothesis by conducting a QST/FST
analysis using agricultural populations of the barley pathogen
Rhynchosporium commune. Population divergence for eight quantitative
traits (QST) was compared with divergence at eight neutral microsatellite
loci (FST) for 126 pathogen strains originating from nine globally
distributed field populations to infer the effects of genetic drift and
types of selection acting on each trait. Our analyses indicated that five
of the eight traits had QST values significantly lower than FST,
consistent with stabilizing selection, whereas one trait, growth under
heat stress (22°C), showed evidence of diversifying selection and local
adaptation (QST>FST). Estimates of heritability were high for all
traits (means ranging between 0.55–0.84), and average heritability across
traits was negatively correlated with microsatellite gene diversity. Some
trait pairs were genetically correlated and there was significant evidence
for a trade-off between spore size and spore number, and between
melanization and growth under benign temperature. Our findings indicate
that many ecologically and agriculturally important traits are under
stabilizing selection in R. commune and that high within-population
genetic variation is maintained for these traits.