Biology subjects

Clo, J.

Publications and source records attributed to Clo, J..

10 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↗

bioRxiv2026

The contribution of non-additive genetic effects to the genetic variance of polyploid species.

Whole genome duplication is a common mutation in eukaryotes with far-reaching phenotypic effects. The resulting morphological, physiological, and fitness consequences and how they affect the survival probability of newly polyploid lineages are intensively studied, but very little is known about the effect of genome doubling on the short-term evolvability of populations. Understanding the effect of polyploidization on the adaptive potential of populations is of crucial importance to predict the future of polyploid populations. In this paper, I investigate the immediate consequences of genome doubling on the genetic variance of populations. To do so, I performed numerical iterations and simulations of how the genetic variance of a quantitative trait changes after polyploidization, under different genetic architectures (additivity, dominance, and epistasis). I found that genetic variance generally decreases after genome doubling. Non-additive gene actions can make autotetraploid populations genetically more diverse than their diploid progenitors in rare cases, notably with overdominance and directional epistasis. By collecting estimates from the agronomic literature, I found that both dominance and epistatic variance contribute to the genetic variance of polyploid populations. These results bring new insights into the adaptive potential of newly formed tetraploid populations, and call for further experimental investigations of how polyploidization is associated with a short-term decrease in evolvability.

genetics↗

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↗

bioRxiv2024

How environment and genetic architecture of unreduced gametes shape the establishment of autopolyploids

It is broadly assumed that polyploidy success is due to an increase in fitness associated with whole genome duplication due to higher tolerance to stressful conditions. In agreement, several theoretical models found that, among other factors, a better tolerance to new environmental conditions can promote polyploidy establishment. These models, however, often made strong hypotheses, for example considering that diploids cannot adapt to new conditions, or that unreduced gametes production is not a limiting factor and that it is of a fixed quantity. In this paper, we challenged some of these hypotheses. We developed a theoretical model in which we modeled the joint evolution of a quantitative trait under selection and the production of unreduced gametes, this trait also being a quantitative trait; both traits were pleiotropically linked. We followed the adaptation of initially diploid populations to a new environment to which neo-tetraploid individuals were directly adapted. The generation of these autotetraploid individuals was enabled by the genetic production of unreduced gametes and by the environmental change modifying the average production of these gametes. We found that for realistic values of unreduced gametes production, adaptation to new environmental conditions was mainly achieved through adaptation of diploids to the new optimum rather than the fixation of newly adapted tetraploid individuals. In broader parameter sets, we found that the adaptation process led to mixed-ploidy populations, except when the populations were swamped with unreduced gametes, and that pleiotropy and environmental effects favored the co-existence of both cytotypes.

evolutionary biology↗

bioRxiv2024

Varying importance of postzygotic isolation in polyploid speciation? A survey of the triploid block strength, its causal mechanisms, and evolutionary consequences

The triploid block, primarily caused by endosperm developmental issues, is known as a significant barrier to interploidy hybridization among flowering plants and thereby, polyploid speciation. However, its strength varies across taxa, with some instances of leakiness, questioning its universal role as a barrier. We conducted a literature survey to explore the causes of the variation in the strength of triploid block across angiosperms. We particularly assessed the impact of interploidy cross direction, types of endosperm development, endosperm persistence at seed maturity, and ploidy divergence. None of these factors had a significant impact on triploid seed viability, likely due to limited data and inconsistencies in estimation methods across the literature. In addition, triploid seed viability in experimental crosses was sometimes correlated to the occurrence of triploid hybrids in nature, sometimes not, suggesting a mixed role of the triploid block in shaping interspecies gene flow. Altogether, our study highlights the need for unified approaches in future studies on the triploid block to advance our understanding of its variation and evolutionary implications.

evolutionary biology↗

bioRxiv2023

Detecting directional epistasis and dominance from cross-line analyses in Alpine populations of Arabidopsis thaliana

The contribution of non-additive genetic effects to the genetic architecture of fitness, and to the evolutionary potential of populations, has been a topic of theoretical and empirical interest for a long time. Yet, the empirical study of these effects in natural populations remains scarce, perhaps because measuring dominance and epistasis relies heavily on experimental line crosses. In this study, we explored the contribution of dominance and epistasis in natural alpine populations of Arabidopsis thaliana, for two fitness traits, the dry biomass and the estimated number of siliques, measured in a greenhouse. We found that, on average, crosses between inbred lines of A. thaliana led to mid-parent heterosis for dry biomass, but outbreeding depression for estimated number of siliques. While heterosis for dry biomass was due to dominance, we found that outbreeding depression for estimated number of siliques could be attributed to the breakdown of beneficial epistatic interactions. We simulated and discussed the implication of these results for the adaptive potential of the studied populations, as well as the use of line-cross analyses to detect non-additive genetic effects.

evolutionary biology↗

bioRxiv2022

Inbreeding depression in polyploid species: a meta-analysis

Whole-genome duplication is a common mutation in eukaryotes with far-reaching phenotypic effects, the resulting morphological and fitness consequences and how they affect the survival of polyploid lineages are intensively studied. Another important factor may also determine the probability of establishment and success of polyploid lineages: inbreeding depression. Inbreeding depression is expected to play an important role in the establishment of neopolyploid lineages, their capacity to colonize new environments, and in the simultaneous evolution of ploidy and other life-history traits such as self-fertilization. Both theoretically and empirically, there is no consensus on the consequences of polyploidy on inbreeding depression. In this meta-analysis, we investigated the effect of polyploidy on the evolution of inbreeding depression, by performing a meta-analysis within angiosperm species. The main results of our study are that the consequences of polyploidy on inbreeding depression are complex and depend on the time since polyploidization. We found that young polyploid lineages have a much lower amount of inbreeding depression than their diploid relatives and their established counterparts. Natural polyploid lineages are intermediate, and have a higher amount of inbreeding depression than synthetic neopolyploids, and a smaller amount than diploids, suggesting that the negative effect of polyploidy on inbreeding depression decrease with time since polyploidization.

evolutionary biology↗

bioRxiv2022

Niche differentiation following whole-genome duplication? The importance of considering the intricate evolutionary history of polyploids when assessing climatic niche evolution

AimAlthough whole genome duplication (WGD) is an important speciation force, we still lack a consensus on the role of niche differentiation in polyploid evolution. In addition, the role of genome doubling per se vs. later divergence on polyploids niche evolution remains obscure. One reason for this might be that the intraspecific genetic structure of polyploid complexes and interploidy gene flow is often neglected in ecological studies. Here, we aim to investigate to which extent these evolutionary processes impact our inference on niche differentiation of autopolyploids. LocationEurope TaxonArabidopsis arenosa (Brassicaceae) MethodsLeveraging a total of 352 cytotyped populations of diploid-autotetraploid A. arenosa, we examined differences among climatic niches of diploid and tetraploid lineages both globally, and independently for each tetraploid lineage with respect to the niche of its evolutionary closest relative. Then, we tested if there was an effect of additional interploidy introgression from other sympatric but more ancestral diploid lineages of A. arenosa on climatic niches of tetraploids. ResultsEcological niche shift of tetraploids is only detected when the assignment of populations to intraspecific genetic lineages is considered. We found different patterns of climatic niche evolution (i.e. niche conservatism, contraction or expansion) in each tetraploid lineage when compared to its evolutionary closest relatives. We observed an effect of interploidy gene flow in patterns of climatic niche evolution of tetraploid ruderal plants of A. arenosa. Main conclusionsThe niche shift of tetraploids in A. arenosa is not driven by WGD per se but rather reflects dynamic post-WGD evolution in the species, involving tetraploid migration out of their ancestral area and interploidy introgression with other diploid lineages. Our study supports that evolutionary processes following WGD - which usually remain undetected by studies neglecting evolutionary history of polyploids - may play a key role in the adaptation of polyploids to challenging environments.

plant biology↗

bioRxiv2019

Hide and seek: hidden genetic variance contributing to the adaptive potential of selfing populations

Standing genetic variation is considered a major contributor to the adaptive potential of species. The low heritable genetic variation observed in self-fertilising populations has led to the hypothesis that species with this mating system would be less likely to adapt. However, a non-negligible amount of cryptic genetic variation for polygenic traits, accumulated through negative linkage disequilibrium, could prove to be an important source of standing variation in self-fertilising species. To test this hypothesis we simulated populations under stabilizing selection subjected to an environmental change. We demonstrate that, when the mutation rate is high (but realistic), selfing populations are better able to store genetic variance than outcrossing populations through genetic associations, notably due to the reduced effective recombination rate associated with predominant selfing. Following an environmental shift, this diversity can be partially remobilized, which increases the additive variance and adaptive potential of predominantly (but not completely) selfing populations. In such conditions, despite initially lower observed genetic variance, selfing populations adapt as readily as outcrossing ones within a few generations. For low mutation rates, purifying selection impedes the storage of diversity through genetic associations, in which case, as previously predicted, the lower genetic variance of selfing populations results in lower adaptability compared to their outcrossing counterparts. The population size and the mutation rate are the main parameters to consider, as they are the best predictors of the amount of stored diversity in selfing populations. Our results and their impact on our knowledge of adaptation under high selfing rates are discussed.

evolutionary biology↗