Biology subjects

Douet, D.

Publications and source records attributed to Douet, D..

3 recordsLinked to original sources

bioRxiv2026

Breakdown of sporophytic self-incompatibility: Diploids versus tetraploids

Many angiosperm species possess self-incompatibility (SI) systems that prevent self-fertilization. Because empirical studies often report higher selfing rates in tetraploids than in diploids, we investigate whether sporophytic self-incompatibility (SSI) is more likely to break down after the introduction of a self-compatible (SC) allele in tetraploid populations. To address this question, we use analytical models and individual-based simulations to compare diploid and tetraploid populations under two main scenarios: (1) all SI alleles are codominant, and (2) SI alleles are structured into dominance classes. Overall, our results indicate that SSI is more difficult to maintain in tetraploids than in diploids, with dominance relationships playing a key role in the invasion success of an SC allele. When SI alleles are organized into dominance classes, increasing the dominance of the SC allele generally favors SSI breakdown in tetraploids, while diploids show weaker sensitivity to dominance, with SSI maintained across all dominance scenarios for the SC allele under sufficiently high inbreeding depression. However, when the SC allele is dominant over all SI alleles, SSI is more readily maintained in both the codominant and dominance-class models.

plant biology↗

bioRxiv2025

Autopolyploid establishment under gametophytic self-incompatibility: the impact of self-fertilization and pollen limitation

Polyploidy is widespread in plants, yet the establishment of neo-polyploids is limited by minority cytotype exclusion (MCE). As polyploidy has been associated with higher selfing rates in empirical studies, a shift from self-incompatibility (SI) to self-compatibility (SC) may help overcome MCE, particularly under ga-metophytic SI (GSI) with non-self-recognition where an automatic shift to SC is associated with polyploidy. We investigated theoretically the joint evolution of polyploidy and self-compatibility and its impact on tetraploid establishment in initially diploid populations with GSI under different pollen limitation scenar-ios, and with fixed or variable selfing rates for polyploids. It is shown that, for high pollen limitation scenarios, autotetraploids can invade an initially diploid population only when the selfing rates are high. Under low pollen limitation, the conditions for tetraploid invasion are less restrictive (selfing rates above 0.3). These results apply to scenarios with either fixed or variable selfing rates in polyploids, but in the latter, high mutation rates of the selfing rate are needed for polyploidy to invade. These results suggest that tetraploid establishment is possible through the evolution of selfing, without introducing a non-functional S-allele. However, the conditions strongly depend on the degree of pollen limitation.

evolutionary biology↗

bioRxiv2025

The effects of ploidy and mating system on the evolvability of populations: theoretical and empirical investigations

The amount of genetic diversity is a key parameter to understand the adaptive potential of populations. It has been demonstrated both theoretically and empirically that several factors influence genetic variance. In angiosperms, two of those are the ploidy level and the mating system of the populations. Polyploidy is theoretically known to increase adaptive potential in the long term. Self-fertilization has been theoretically associated with a decrease in genetic variance, even if it lacks empirical support. These factors have been studied independently, but are often shared in plants. However, there is a lack of empirical studies about the joint effects of polyploidy and selfing on genetic variance. In this paper, we conducted theoretical simulations to explore how genetic diversity could be affected by the ploidy level and mating system. We compared the simulation results with empirical estimates of genetic variance from the plant species Erysimum incanum, a selfing species from the Western Mediterranean basin exhibiting three different ploidy levels. We measured a series of phenotypic traits in individuals of each ploidy, obtained by controlled crosses and grown in different climatic conditions. While theoretical approaches showed a positive relationship between ploidy and genetic variance in both the short and long term, empirical results show lower evolvability and transgressive segregation for polyploids, both results being dependent on environmental conditions. Genetic variance in E. incanum polyploids could be related to recent establishment and adaptation to harsh environments, which explains the apparent contradiction with theory, where more settled and established populations are considered.

evolutionary biology↗