Consequences of self-fertilization and the maintenance of gynodioecy in the bladder campion (Silene vulgaris)

TitleConsequences of self-fertilization and the maintenance of gynodioecy in the bladder campion (Silene vulgaris)
Publication TypeJournal Article
Year of Publication1987
AuthorsJolls CL
JournalAssociation of Southeastern Biologists Bulletin

Gynodioecy, the occurrence of hermaphroditic and female plants within the same population, has been hypothesized to promote outcrossing. This presumably confers an advantage on the offspring through the benefits of heterosis, the avoidance of inbreeding depression, or both. I tested this hypothesis by comparing offspring of gynodioecious Silene vulgaris. Seeds of self-fertilized hermaphrodites, cross-fertilized hermaphrodites, and cross-fertilized females were obtained by artificial pollinations of field plants. Four hundred randomly selected seed were weighed, sown without bias in a mist bed of a constant temperature greenhouse. For six weeks, I recorded germination daily, height weekly, and determined leaf number, area and biomass at the end of the experiment. Seeds of outcrossed females were significantly heavier than those of the selfed or outcrossed hermaphrodites (.9226 vs. .8414 vs. .8115 mg, respectively, F=7.45, df=2,397, p=.0007). These larger seeds of females germinated a day earlier on the average and with greater success than those of selfed hermaphrodites (12.6 vs. 11.6, F=3.72, df=2.328, p=.0251 and 86% vs 77%, x2=14.67, p=.001). Although there was no significant difference among offspring leaf number, the outcrossed females and hermaphrodites produced seedlings with greater leaf area than did selfed plants (9.3 and 9.0 vs. 6.8 cm2, f=8.93, df=2.292, p=.0002). I discuss these results in light of the maintenance of females in populations of protandrous, entomophilous hermaphrodites and the possibility of adaptive cytoplasmic factors in gynodioecious taxa.