Biology subjects

Oddou-Muratorio, S.

Publications and source records attributed to Oddou-Muratorio, S..

3 recordsLinked to original sources

bioRxiv2023

Intertwining of fecundity, sexual and growth selection on spring phenology along an altitudinal gradient of European beech (Fagus sylvatica L.).

BackgroundPlant phenological traits such as the timing of budburst or flowering can evolve on ecological timescales through response to fecundity and viability selection. However, interference with sexual selection may arise from assortative mating. This study aims to investigate how these three components of selection on spring phenology may combine in European beech populations in contrasting environments (high versus low altitude). Methodswe monitored the timing of budburst (TBB) in 339 adult beech trees and estimated their fecundity using spatially explicit mating models. Fecundity selection was infered by regressing fecundities on TBB, while sexual selection was inferred by regressing fecundities on mating opportunities (i.e., TBB mismatch). The correlation between mates for flowering time (i.e., assortative mating) was estimated based on paternity analyses. Morever, TBB and growth were surveyed in 3261 seedlings from 40 families grown planted in a common garden, and viability selection was inferred by regressing growth on TBB. ResultsOverall, directional fecundity selection on female fitness favored trees with earlier TBB. Sexual selection acted only on male fitness through assortative mating favoring trees with mean TBB value (stabilizing selection). In the common garden, early budburst was associated with higher seedling growth. The respective intensities of directional and stabilizing selection varied with the environment: at low altitude, directional selection for earlier phenology was modulated by strong assortative mating and by an interaction effect between TBB an size on female fecundity, whereas at high altitude, directional selection for earlier phenology was reinforced by selection through male fecundity. DiscussionThis study showed that selection through female fecundity and seedlings growth predominantly selected for earlier TBB, while sexual selection on male fitness through assortative mating modulated this trend. This interplay between fecundity and sexual selection calls for an integrative approach to predict the evolution of spring phenology under a changing climate.

evolutionary biology↗

bioRxiv2021

A hierarchical Bayesian model to investigate trade-offs between growth and reproduction in a long-lived plant

1A trade-off between growth and fecundity, reflecting the inability of simultaneously investing in both functions when resources are limited, is a fundamental feature of life history theory. This particular trade-off is the result of evolutionary and environmental constrains shaping reproductive and growth traits, but it remains difficult to pinpoint in natural populations of long-lived plants. We developed a hierarchical Bayesian model to estimate the inter-individual correlation among growth and reproduction, using observations at individual level over several years combined with resource simulations from an ecophysiological-based model (CASTANEA). In the Bayesian model, the resource, simulated by CASTANEA and incorporated as a latent variable, is allocated to tree growth, reproductive buds initiation and fruit maturation. Then, we used individual random effects correlated among energetic sinks to investigate potential trade-offs. We applied this original approach to a Mediterranean coniferous tree, Atlas Cedar (Cedrus atlantica), at two contrasted levels of competition, high versus low density population. We found that trees initializing many reproductive buds had a higher growth. Moreover, a negative correlation was detected between growth and fruit survival during maturation. Finally, trees investing more resource to maturate fruits initiated less reproductive buds. The level of competition did not impact the sign of these three correlations, but changed the level of resource allocation: low density population favored growth whereas high density favored reproduction. The level of resource have an impact on individual strategies. This new modeling framework allowed us to detect various individual strategies of resource allocation to growth versus late-stage reproduction on the one hand, and to early-versus late-stage reproduction on the other hand. Moreover, the sign of the correlation between growth and reproductive traits depends on the stage of reproduction considered. Hence, we suggest that the investigation of potential trade-offs between growth and reproduction requires to integrate the dynamics of resource and sinks phenology, from initiation to maturation of reproductive organs.

ecology↗

bioRxiv2018

Crown defoliation decreases reproduction and wood growth in a marginal European beech population.

O_LIAbiotic and biotic stresses related to climate change have been associated to increased crown defoliation, decreased growth and a higher risk of mortality in many forest tree species, but the impact of stresses on tree reproduction and forest regeneration remains understudied. At dry, warm margin of species distributions, flowering, pollination and seed maturation processes are expected to be affected by drought, late frost and other stresses, eventually resulting in reproduction failure. Moreover, inter-individual variations in reproductive performances versus other performances (growth, survival) could have important consequences on populations dynamics.\nC_LIO_LIWe investigated the relationships between individual crown defoliation, growth and reproduction in a drought-prone population of European beech, Fagus sylvatica. We used a spatially explicit mating model and marker-based parentage analyses to estimate effective female and male fecundities of 432 reproductive trees, which were also monitored for basal area increment and crown defoliation over nine years.\nC_LIO_LIFemale and male fecundities markedly varied among individuals, more than did growth. Both female fecundity and growth decreased with increasing crown defoliation and competition and increased with size. Male fecundity only responded to competition, and decreased with increasing competition. Moreover, the negative effect of defoliation on female fecundity was size-dependent, with a slower decline in female fecundity with increasing defoliation for the large individuals. Finally, a trade-off between growth and female fecundity was observed in response to defoliation: some large trees maintained significant female fecundity at the expense of reduced growth in response to defoliation, while some other defoliated trees rather maintained high growth at the expense of reduced female fecundity.\nC_LIO_LISynthesis. Our results suggest that while decreasing their growth, some large defoliated trees still contribute to reproduction through seed production and pollination. This non-coordinated decline of growth and fecundity at individual-level in response to stress may compromise the evolution of stress-resistance traits at population level, and increase forest tree vulnerability.\nC_LI

ecology↗