When is it worth being a self‐compatible hermaphrodite? Context‐dependent effects of self‐pollination on female advantage in gynodioeciousSilene nutans

Abstract

In gynodioecious plant species with nuclear-cytoplasmic sex determination, females and hermaphrodites plants can coexist whenever female have higher seed fitness than hermaphrodites. Although the effect of self fertilization on seed fitness in hermaphrodites has been considered theoretically, this effect is far from intuitive, because it can either increase the relative seed fitness of the females (if it leads hermaphrodites to produce inbred, low quality offspring) or decrease it (if it provides reproductive assurance to hermaphrodites). Hence, empirical investigation is needed to document whether relative seed fitness varies with whether pollen is or is not limiting to seed production. In the current study, we measured fruit set and seed production in both females and hermaphrodites and the selfing rate in hermaphrodites in two experimental patches that differed in sex ratios in the gynodioecious plant Silene nutans. We found an impact of plant gender, patch, and their interaction, with females suffering from stronger pollen limitation when locally frequent. In the most pollen-limited situation, the selfing rate of hermaphrodites increased and provided hermaphrodites with a type of reproductive assurance that is not available to females. By integrating both the beneficial (reproductive assurance) and costly effects (through inbreeding depression) of self-pollination, we showed that whether females did or did not exhibit higher seed fitness depended on the degree of pollen limitation on seed production.

Lineages ofSilene nutansdeveloped rapid, strong, asymmetric postzygotic reproductive isolation in allopatry

“…To ascertain adequate convergence of the Markov Chain Monte Carlo (MCMC) model, we allowed a burn-in of 100,000 iterations, followed by 2 × 10 6 MCMC replications without any prior geographic information on the putative affiliation of individuals. However, the assumption of panmixia implied in such Bayesian clustering does not necessarily hold in S. nutans, which can exhibit a mixed-mating system and female individuals (Lahiani et al 2015). CLUMP version 1.1.2 (Jakobsson and Rosenberg 2007) was used to find the optimal alignment of independent runs by averaging the top runs.…”

“…The resulting most likely grouping of populations was plotted using DISTRUCT version 1.1 (Rosenberg 2004). However, the assumption of panmixia implied in such Bayesian clustering does not necessarily hold in S. nutans, which can exhibit a mixed-mating system and female individuals (Lahiani et al 2015). To avoid this potential bias, we performed a Principal Component Analysis (PCA) using adegenet R package (Jombart 2008; R Core Team Development 2014), which does not require any genetic assumptions, within each region.…”

Theory of coevolution of cytoplasmic male-sterility, nuclear restorer and selfing

“…Theoretical studies have found that in a gynodioecious population, autogamous selfing can be an effective assurance for hermaphrodite reproduction (Maurice & Fleming, 1995). Indeed, Lahiani et al (2015) empirically measured seed production, strength of pollen limitation, and the selfing rates of hermaphroditic individuals in both female-biased and hermaphrodite-biased gynodioecious populations. They clearly indicated that selfing can be a reproductive assurance, by which hermaphrodites are more tolerant to pollen limitation than females especially in female-biased populations.…”

Mating System among Provenances of Sclerocarya birrea (A. Rich.) Hochst.

“…In the present study, there was fruit development in buds that were covered by fine nets. Fruit development in this treatment signifies cross-pollination by wind or selfing by hermaphrodite flowers [34]. The results therefore suggest that the enclosed flower bud got fertilized by pollen blown by wind from male flowers of other trees within the trial.…”