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Beyond balancing selection: frequent mitochondrial recombination contributes to high-female frequencies in gynodioecious Lobelia siphilitica (Campanulaceae).
New Phytol 2019; 224(3):1381-1393NP

Abstract

Gynodioecy is a sexual system in which 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. To test for balancing selection and/or the repeated introduction of novel CMS, we characterised cytoplasmic haplotypes from 61 populations of Lobelia siphilitica that vary widely in female frequency. 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. 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.

Authors+Show Affiliations

Department of Biological Sciences, Kent State University, Kent, OH, 44240, USA. Department of Biological and Environmental Sciences, Longwood University, Farmville, VA, 23909, USA.Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada.Department of Biological Sciences, Kent State University, Kent, OH, 44240, USA.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31442304

Citation

Adhikari, Binaya, et al. "Beyond Balancing Selection: Frequent Mitochondrial Recombination Contributes to High-female Frequencies in Gynodioecious Lobelia Siphilitica (Campanulaceae)." The New Phytologist, vol. 224, no. 3, 2019, pp. 1381-1393.
Adhikari B, Caruso CM, Case AL. Beyond balancing selection: frequent mitochondrial recombination contributes to high-female frequencies in gynodioecious Lobelia siphilitica (Campanulaceae). New Phytol. 2019;224(3):1381-1393.
Adhikari, B., Caruso, C. M., & Case, A. L. (2019). Beyond balancing selection: frequent mitochondrial recombination contributes to high-female frequencies in gynodioecious Lobelia siphilitica (Campanulaceae). The New Phytologist, 224(3), pp. 1381-1393. doi:10.1111/nph.16136.
Adhikari B, Caruso CM, Case AL. Beyond Balancing Selection: Frequent Mitochondrial Recombination Contributes to High-female Frequencies in Gynodioecious Lobelia Siphilitica (Campanulaceae). New Phytol. 2019;224(3):1381-1393. PubMed PMID: 31442304.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Beyond balancing selection: frequent mitochondrial recombination contributes to high-female frequencies in gynodioecious Lobelia siphilitica (Campanulaceae). AU - Adhikari,Binaya, AU - Caruso,Christina M, AU - Case,Andrea L, Y1 - 2019/09/21/ PY - 2019/07/14/received PY - 2019/08/13/accepted PY - 2019/8/24/pubmed PY - 2019/8/24/medline PY - 2019/8/24/entrez KW - Lobelia siphilitica KW - balancing selection KW - cytoplasmic male sterility KW - gynodioecy KW - haplotype diversity KW - linkage disequilibrium KW - mitochondrial recombination SP - 1381 EP - 1393 JF - The New phytologist JO - New Phytol. VL - 224 IS - 3 N2 - Gynodioecy is a sexual system in which 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. To test for balancing selection and/or the repeated introduction of novel CMS, we characterised cytoplasmic haplotypes from 61 populations of Lobelia siphilitica that vary widely in female frequency. 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. 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. SN - 1469-8137 UR - https://www.unboundmedicine.com/medline/citation/31442304/Beyond_balancing_selection:_frequent_mitochondrial_recombination_contributes_to_high_female_frequencies_in_gynodioecious_Lobelia_siphilitica_L._(Campanulaceae) L2 - https://doi.org/10.1111/nph.16136 DB - PRIME DP - Unbound Medicine ER -