Data from: Beyond balancing selection: frequent mitochondrial recombination contributes to high female frequencies in gynodioecious Lobelia siphilitica L. (Campanulaceae)
Caruso, Christina M.
Case, Andrea L.
Published Sep 13, 2019 on Dryad.
Cite this dataset
Adhikari, Binaya; Caruso, Christina M.; Case, Andrea L. (2019). Data from: Beyond balancing selection: frequent mitochondrial recombination contributes to high female frequencies in gynodioecious Lobelia siphilitica L. (Campanulaceae) [Dataset]. Dryad. https://doi.org/10.5061/dryad.ss25rp7
(1) Gynodioecy is a sexual system where females and hermaphrodites co-occur. In most gynodioecious angiosperms, sex is determined by an interaction between mitochondrial male-sterility genes (CMS) that arise via recombination and nuclear restorer alleles that evolve to suppress them. In theory, gynodioecy occurs when multiple CMS types are maintained at equilibrium frequencies by balancing selection. However, some gynodioecious populations contain very high frequencies of females. High female frequencies are not expected under balancing selection, but could be explained by the repeated introduction of novel CMS types.
(2) To test for balancing selection and/or the repeated introduction of novel CMS, we characterized cytoplasmic haplotypes from 61 populations of Lobelia siphilitica that vary widely in female frequency.
(3) We confirmed that mitotype diversity and female frequency were positively correlated across populations, consistent with balancing selection. However, while low-female populations hosted mostly common mitotypes, high-female populations and female plants hosted mostly rare, recombinant mitotypes likely to carry novel CMS types.
(4) Our results suggest that balancing selection maintains established CMS types across this species, but extreme female frequencies result from frequent invasion by novel CMS types. We conclude that balancing selection alone cannot account for extreme population sex-ratio variation within a gynodioecious species.
Distribution of cytoplasmic haplotypes among populations of Lobelia siphilitica varying in sex ratio
Distribution of plastid and 3-locus mitochondrial haplotypes among 220 individuals of Lobelia siphilitica. Individual samples are identified by their population of origin, population location (US state or Canadian province), and the sex of the plant (female, F or hermaphrodite, H). Average population sex ratio (percent female averaged across years) and sex-ratio quartile (0%, 0.1-10%, 10.1-50%, >50% female) are also shown. Plastid haplotypes are based on intergenic sequences of psbK–rps16, excluding an imperfect minisatellite locus (13 unique haplogroups labeled 'C#'). Concatenated 3-locus mitochondrial haplotypes are based on sequenced alleles of nad7ab (A–K), atp6 (1–11) and Ψrps12 (a–f). '_' indicates missing sequences for a particular mitochondrial allele. Mitotype classes: C= common mitotypes found in at least 5 individuals and at least 3 populations; RA= rare mitotypes with rare alleles for at least one marker locus; RR= rare combinations of common alleles at each marker locus.