Data from: Fine-scale genetic structure in the orchid Gymnadenia conopsea is not associated with local density of flowering plants

Premise: Density-dependent pollinator visitation can lead to
density-dependent mating patterns and within-population genetic structure.
In Gymnadenia conopsea, individuals in low-density patches receive more
self-pollen than individuals in high-density patches, suggesting higher
relatedness at low density. Ongoing fragmentation is also expected to
cause more local matings, potentially leading to biparental inbreeding
depression. Methods: To evaluate whether relatedness decreases with local
density, we analysed 1315 SNP loci in 113 individuals within two large
populations. We quantified within-population genetic structure in one of
the populations, recorded potential habitat barriers, and visualized gene
flow using estimated effective migration surfaces (EEMS). We further
estimated the magnitude of biparental inbreeding depression that would
result from matings restricted to within 5 m. Results: There was no
significant relationship between local density and relatedness in any
population. We detected significant fine-scale genetic structure
consistent with isolation-by-distance, with positive kinship coefficients
at distances below 10 m. Kinship coefficients were low, and predicted
biparental inbreeding depression resulting from matings within the closest
5 m was a modest 1–3%. EEMS suggested that rocks and bushes may act as
barriers to gene flow within a population. Conclusions: The results
suggest that increased self-pollen deposition in sparse patches does not
necessarily cause higher selfing rates, or that inbreeding depression
results in low establishment success of inbred individuals. The modest
relatedness suggests that biparental inbreeding depression is unlikely to
be an immediate problem following fragmentation of large populations. The
results further indicate that habitat structure may contribute to
governing fine-scale genetic structure in G. conopsea.