A Quantitative Genetic Analysis of Nuclear-Cytoplasmic Male Sterility in Structured Populations of Silene vulgaris

Corresponding author: Douglas R. Taylor, Department of Biology, Gilmer Hall, University of Virginia, Charlottesville, VA 22903., drt3b{at}virginia.edu (E-mail)

Communicating editor: R. G. SHAW

Gynodioecy, the coexistence of functionally female and hermaphroditic morphs within plant populations, often has a complicated genetic basis involving several cytoplasmic male-sterility factors and nuclear restorers. This complexity has made it difficult to study the genetics and evolution of gynodioecy in natural populations. We use a quantitative genetic analysis of crosses within and among populations of Silene vulgaris to partition genetic variance for sex expression into nuclear and cytoplasmic components. We also use mitochondrial markers to determine whether cytoplasmic effects on sex expression can be traced to mitochondrial variance. Cytoplasmic variation and epistatic interactions between nuclear and cytoplasmic loci accounted for a significant portion of the variation in sex expression among the crosses. Source population also accounted for a significant portion of the sex ratio variation. Crosses among populations greatly enhanced the dam (cytoplasmic) effect, indicating that most among-population variance was at cytoplasmic loci. This is supported by the large among-population variance in the frequency of mitochondrial haplotypes, which also accounted for a significant portion of the sex ratio variance in our data. We discuss the similarities between the population structure we observed at loci that influence sex expression and previous work on putatively neutral loci, as well as the implications this has for what mechanisms may create and maintain population structure at loci that are influenced by natural selection.

This article has been cited by other articles:

				M{a} L. Buide Disentangling the causes of intrainflorescence variation in floral traits and fecundity in the hermaphrodite Silene acutifolia Am. J. Botany, April 1, 2008; 95(4): 490 - 497. [Abstract] [Full Text] [PDF]

				M. F. Bailey and L. F. Delph Sex-Ratio Evolution in Nuclear-Cytoplasmic Gynodioecy When Restoration Is a Threshold Trait Genetics, August 1, 2007; 176(4): 2465 - 2476. [Abstract] [Full Text] [PDF]

				M. E. Welch, M. Z. Darnell, and D. E. McCauley Variable Populations Within Variable Populations: Quantifying Mitochondrial Heteroplasmy in Natural Populations of the Gynodioecious Plant Silene vulgaris Genetics, October 1, 2006; 174(2): 829 - 837. [Abstract] [Full Text] [PDF]

				P. K. Ingvarsson and D. R. Taylor Genealogical evidence for epidemics of selfish genes PNAS, August 20, 2002; 99(17): 11265 - 11269. [Abstract] [Full Text] [PDF]