Gynodioecy in Silene vulgaris (Caryophyllaceae): Progeny Success, Experimental Design, and Maternal Effects

Abstract

This study documents the comparative success of seeds and seedlings of the perennial gynodioecious-gynomonoecious weed, Silene vulgaris. in the greenhouse. The importance of experimental design is stressed by comparing two different statistical analyses ofthe data. Seeds were obtained from artificial pollinations in the field: self-fertilization of hermaphrodites, and crossfertilizations of both hermaphrodites and females. One-way analysis of variance using progeny type (selfed hermaphrodites, outcrossed hermaphrodites, and outcrossed females) as the treatment effect for each seed and seedling variable showed statistically discernable differences among progeny from different cross types. The significance of this type of ANOV A resulted from a reduced error term and positively-biased F ratios. A factorial design showed no significant differences due to type of progeny in seed mass, days to germination, leaf number, area, or biomass at six weeks of age. There were, however, significant differences among seeds attributable to maternal parent for all seed and seedling variables. A higher proportion of seeds from outcrossed individuals germinated compared to that from self-fertilization. When the data were analyzed to include and partition all sources of variation, differences among offspring appeared during germination, rather than during later development. Seed mass, cross type, and sex of maternal parent all significantly affected the likelihood of germination; however, they had decreasing predictive power, respectively. Inbreeding depression in Silene vulgaris may help maintain gynodioecy; however, the pleiotropic effects of both nuclear and cytoplasmic genes for sex expression also may affect fitness and the maintenance of females. THE TERM "gynodioecious" was used by Darwin (1877) for Thymus serpyllum to describe the occurrence offema1es and hermaphrodites within the same population of a plant species. Since that time, many hypotheses have attempted to explain the occurrence of two dif-I

Effects of Maternal and Paternal Environment and Genotype on Offspring Phenotype in Solidago altissima L.

“…These differences were carried over to a diminishing degree to later characters in the life cycle, as indicated by the significant effects of the covariate seed mass in the analyses of the glasshouse experiment. Such effects of seed mass have often been described in the literature (Roach and Wulff 1987 and references therein;Nakamura 1988;Jolls and Chenier 1989;Stratton 1989;Rocha andStephenson 1990, 1991;Stock et al 1990;Gross and Smith 1991;Houssard and Escarre 1991;Krannitz et al 1991;McCall et al 1991).…”

FREQUENCY‐DEPENDENT FITNESS INSILENE VULGARIS, AGYNODIOECIOUS PLANT

“…Silene vulgaris (Caryophyllaceae) is a short-lived perennial, weedy plant. It has been described as gynodioecious because both functionally hermaphroditic and male sterile individuals coexist in the same populations, along with a low incidence of intersexes, or individuals bearing both hermaphroditic and male sterile flowers (Jolls and Chenier 1989). The sex ratio of natural populations has been observed to vary from all hermaphrodite to as much as 75% female (pers.…”

“…Fruits may bear more than 100 seeds. Silene vulgaris is pollinated by bees and moths and is known to be self-fertile (Charlesworth 1989;Jolls and Chenier 1989;Pettersson 1992).…”

Sex expression and fruit set in Silene littorea (Caryophyllaceae): variation among populations

“…Silene littorea, like other species of the genus (S. vulgaris, Jolls & Chenier 1989), shows polygamy, with populations comprising female-flower-only, hermaphrodite-flower-only and mixed-type individuals.…”