MAINTENANCE OF GYNODIOECY IN SILENE ACAULIS (CARYOPHYLLACEAE): STAGE‐SPECIFIC FECUNDITY AND VIABILITY SELECTION

• Published in: American Journal of Botany
• Main Author: Shykoff, Jacqui A.
• Other Authors: National Science Foundation
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1988
• Subjects: Silene acaulis
• Online Access: http://dx.doi.org/10.1002/j.1537-2197.1988.tb13507.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fj.1537-2197.1988.tb13507.x; https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.1537-2197.1988.tb13507.x; http://api.wiley.com/onlinelibrary/chorus/v1/articles/10.1002%2Fj.1537-2197.1988.tb13507.x

Through a combination of field and greenhouse experiments, I examined the factors contributing to the maintenance of female individuals in natural populations of the gynodioecious alpine plant Silene acaulis (Caryophyllaceae). Hand‐pollinated female plants produced 3.8 times as many seeds as did either self‐ or outcross‐pollinated hermaphrodites, and open‐pollinated females produced 2.9 times as many seeds as open‐pollinated hermaphrodites. Females and hermaphrodites produce seeds of similar mass, and the same number of seeds per fruit, but females set fruit from a higher proportion of their flowers. This fecundity difference alone is sufficient to sustain equilibrium frequencies of females in natural populations. Greenhouse germination trials revealed no difference in the timing or probability of germination among seeds produced from females, selfed, and outcrossed hermaphrodites. Seedlings produced by females had the highest juvenile survivorship followed by those from outcrossed hermaphrodites and then those from selfed hermaphrodites. Differences between selfed hermaphrodites and the other treatments provide evidence for inbreeding depression at the establishment stage. The discrepancy between success of seedlings from female plants and those from outcrossed hermaphrodites suggests either that superior resources are allocated to seeds by females (maternal effect) or that seedlings of females are genetically superior to those of hermaphrodites.