Inherited dimorphism in cleistogamous flower production in Portulaca oleracea: a comparison of 16 populations growing under different environmental conditions

Abstract

Background and Aims Cleistogamy is considered to be an adaptive strategy resulting in plasticity in CH and CL flower production depending on environmental conditions and plant size. The aim of this study was to investigate whether CH and CL flower production in Portulaca oleracea is genetically differentiated among populations in association with climatic conditions. Methods First, we conducted growth experiments with P. oleracea seedlings from 16 populations under two temperature conditions. Second, we sowed seeds originating from the parents in the first experiment and grew the resulting plants to investigate whether flower production is heritable and plants in the same population show the same pattern of flower production. Key Results Two types of plants that produced only CH or CL flowers (referred to as CH and CL plants, respectively) were mainly observed, and the growing temperature conditions did not affect flower production. The frequency of CL plants increased with a decrease in the mean temperature in the original population. CL plants tended to begin reproduction earlier than CH plants, and the probability that a CH plant would flower decreased under the low-growing temperature conditions. Thus, CL plants may have some advantages in unfavourable environments in which early reproduction is necessary due to a short growing season and/or CH flowers cannot open due to low temperatures. The progeny originating from CH and CL plants also produced only CH and CL flowers, respectively, suggesting that there is a genetic basis for the dimorphism in flower production in P. oleracea, represented by CH and CL plants. Conclusions In contrast to the previous hypothesis that the production of both CH and CL flowers would be plastic, the genotypes producing either CH or CL flowers occurred at different frequencies under varying climatic conditions.

Fire frequency effects on cleistogamy expression and progeny performance inCologania broussonetii

“…Thus, cleistogamy expression in C. broussonetii would be mainly prompted by abiotic factors such as degraded microenvironmental conditions, as documented elsewhere for other CL species ( e.g . Uphof 1938; Stojanova et al 2020; Furukawa et al 2020; Sternberger et al 2020). However, despite the lack of influence of the pollination environment in the expression of cleistogamy in our study sites, we did observe differences in the relative reproductive success between CH and CL flowers in burned sites, where CH flowers set more seeds than CL flowers in both low and high fire frequency conditions.…”

“…Environmental factors such as soil moisture and nutrition, light levels and plant size may influence the production of CL and CH flowers (Lu 2002; Munguía‐Rosas et al 2013; Furukawa et al 2020). At the microsite scale, abiotic resource limitation usually increases cleistogamy expression, as this phenotype provides a high ratio of fitness/cost returns, maximizing reproductive success (Lloyd 1984; Veena & Nampy 2019; Stojanova et al 2020; Sternberger et al 2020).…”

Selective forces on the maintenance of outcrossing in an almost exclusively cleistogamous violet species

“…Cleistogamy has evolved independently multiple times (Desfeux et al, 1996), and there are few, if any, documented cases of loss of the CH flowers. This peculiar reproductive strategy, and why it is maintained, has puzzled biologists for a long time, and continues to do so because it goes against the prediction that mixed mating is not evolutionarily stable (Goodwillie et al, 2005; Oakley and Winn, 2008; Winn and Moriuchi, 2009; Ansaldi et al, 2019; Furukawa et al, 2020). Yet, experimental studies have revealed certain conditions (e.g., pollen limitation) that would allow mixed mating systems to be evolutionarily stable (Albert et al, 2011; Stojanova et al, 2020).…”

“…The strategy for producing the two flower morphs may be selected under certain circumstances. Factors such as light quantity, soil moisture, temperature, herbivory, and plant size can affect the relative number of CH and CL flowers produced (Waller, 1980; Berg and Redbo‐Torstensson, 1999; Forrest and Thomson, 2008; Furukawa et al, 2020; Sternberger et al, 2020). According to the ‘adaptive plasticity hypothesis,’ cleistogamy is favored under heterogeneous and stressful environments (e.g., water deficient and scarce pollinators), which are unsuitable for cross‐pollination (Schoen and Lloyd, 1984; Culley, 2002; Albert et al, 2011).…”

“…Heterosis (i.e., the increased fitness of offspring from crosses between different populations or species) might reduce these fixed mutations masking the deleterious recessive alleles in a heterozygote recombination. Although both variance discounting and heterosis might contribute to the maintenance of CH flowers in cleistogamous species, additional forces (e.g., environmental conditions) may explain the higher fitness cost of CH flowers compared to CL flowers in some species (Oakley et al, 2007; Furukawa et al, 2020).…”