Data from: Disentangling the effects of mating systems and mutation rates on cytoplamic diversity in gynodioecious Silene nutans and dioecious Silene otites

Many flowering plant species exhibit a variety of distinct sexual morphs,
the two most common cases being the co- occurrence of females and males
(dioecy) or the co-occurrence of hermaphrodites and females (gynodioecy).
In this study we compared DNA sequence variability of the three genomes
(nuclear, mitochondrial and chloroplastic) of a gynodioecious species,
Silene nutans, with that of a closely related dioecious species, Silene
otites. In the light of theoretical models, we expect cytoplasmic
diversity to differ between the two species due to the selective dynamics
that acts on cytoplasmic genomes in gynodioecious species: under an
epidemic scenario, the gynodioecious species is expected to exhibit lower
cytoplasmic diversity than the dioecious species, while the opposite is
expected in the case of balancing selection maintaining sterility
cytoplasms in the gynodioecious species. We found no difference between
the species for nuclear gene diversity, but, for the cytoplasmic loci, the
gynodioecious S. nutans had more haplotypes, and higher nucleotide
diversity, than the dioecious relative, S. otites, even though the latter
has a relatively high rate of mitochondrial synonymous substitutions, and
therefore presumably a higher mutation rate. Therefore, since the
mitochondrial mutation rate cannot account for the higher cytoplasmic
diversity found in S. nutans, our findings support the hypothesis that
gynodioecy in S. nutans has been maintained by balancing selection rather
than by epidemic-like dynamics.