Physiological effects of temperature do not explain prevalence of females in populations of gynodioecious growing in warmer climates.

Premise Of The Study: Gynodioecy is a sexual polymorphism whereby female and hermaphroditic plants co-occur within populations. In many gynodioecious species, stressful abiotic environments are associated with higher frequencies of females. This association suggests that abiotic stress affects the relative fitness of females and hermaphrodites and, thus, the maintenance of gynodioecy.

The evolutionary ecology of cytonuclear interactions in angiosperms.

Interactions between cytoplasmic and nuclear genomes have significant evolutionary consequences. In angiosperms, the most common cytonuclear interaction is between mitochondrial genes that disrupt pollen production (cytoplasmic male sterility, CMS) and nuclear genes that restore it (nuclear male fertility restorers, Rf). The outcome of CMS/Rf interactions can depend on whether Rf alleles have negative pleiotropic effects on fitness.

The nearness of you: the effect of population structure on siring success in a gynodioecious species.

Theoretically, both balancing selection and genetic drift can contribute to the maintenance of gender polymorphism within and/or among populations. However, if strong differences exist among genotypes in the quantity of viable gametes they produce, then it is expected that these differences will play an important role in determining the relative frequency of the genotypes and contribute to whether or not such polymorphism is maintained. In this issue, De Cauwer et al.

Recent advances in the study of gynodioecy: the interface of theory and empiricism.

Background: In this review we report on recent literature concerned with studies of gynodioecy, or the co-occurrence of female and hermaphrodite individuals in natural plant populations. Rather than review this literature in its entirety, our focus is on the interplay between theoretical and empirical approaches to the study of gynodioecy.

Scope: Five areas of active inquiry are considered.

Sex-ratio evolution in nuclear-cytoplasmic gynodioecy when restoration is a threshold trait.

Gynodioecious plant species, which have populations consisting of female and hermaphrodite individuals, usually have complex sex determination involving cytoplasmic male sterility (CMS) alleles interacting with nuclear restorers of fertility. In response to recent evidence, we present a model of sex-ratio evolution in which restoration of male fertility is a threshold trait. We find that females are maintained at low frequencies for all biologically relevant parameter values.

Inheritance of chloroplast DNA is not strictly maternal in Silene vulgaris (Caryophyllaceae): evidence from experimental crosses and natural populations.

Chloroplast DNA (cpDNA) is maternally inherited in the majority, but not all, of angiosperm species. The mode of inheritance of cpDNA is a critical determinant of its molecular evolution and of its population genetic structure. Here, we present the results of investigations of the inheritance of cpDNA in Silene vulgaris, a plant used in a variety of studies in which cpDNA is an important component.

Merging theory and mechanism in studies of gynodioecy.

In gynodioecious species, females and hermaphrodites coexist and the genetics of sex determination is usually nuclear cytoplasmic. Maintaining nuclear-cytoplasmic gynodioecy requires polymorphism for the feminizing genes (contained in the mitochondria) and the genes that restore male fertility (contained in the nucleus). This complex polymorphism depends, in part, on there being negative pleiotropic effects (i.

Offspring sex ratio under inbreeding and outbreeding in a gynodioecious plant.

Silene vulgaris is a gynodioecious plant native to Eurasia and now found throughout much of North America. Using hermaphrodite plants from three geographic regions (Stamford, NY; Broadway,VA; and Giles Co., VA) and four local populations within each region, we employed a hierarchical crossing design to explore the geographic structure of sex determining genes.

Modeling gynodioecy: novel scenarios for maintaining polymorphism.

Nuclear-cytoplasmic gynodioecy is a breeding system of plants in which females and hermaphrodites co-occur in populations, and gender is jointly determined by cytoplasmic male sterility (CMS) genes and nuclear restorers of male fertility. Persistent polymorphism at both CMS and nuclear-restorer loci is necessary to maintain this breeding system. Theoretical models have explained how nuclear-cytoplasmic gynodioecy can be stable for certain assumptions.

A cost of restoration of male fertility in a gynodioecious species, Lobelia siphilitica.

Models allowing the coexistence of females and hermaphrodites in gynodioecious populations assume a simple genetic system of sex determination, a seed fitness advantage of females (compensation), and a negative pleiotropic effect of nuclear sex-determining genes on fitness (cost of restoration). In Lobelia siphilitica, sex is determined by both mitochondrial genes causing cytoplasmic male sterility (CMS) and nuclear genes that restore fertility when present with specific CMS haplotypes (nuclear restorers). I tested for a cost of restoration in L.