Biology subjects

Fereol, S.

Publications and source records attributed to Fereol, S..

4 recordsLinked to original sources

bioRxiv2026

Environmental tolerance, species interaction, and the link between the fundamental and realized niches: Insights from a hypersaline planktonic system

The impacts of a changing abiotic environment on fitness and performance arise not only from low tolerance to new environmental conditions, but also from changes in the abundance and interaction intensity with other species. The strength of the interaction may itself depend on how well each species performs across environments, but there is a dearth of studies investigating how intrinsic fitness and interaction intensity covary across an abiotic environmental gradient. We addressed this question in a hypersaline consumer-resource system: the microalga Dunaliella spp. grazed by the brine shrimp Artemia franciscana. We exposed four Dunaliella strains to a range of salinities above seawater, with or without brine shrimps, and tracked their population sizes over time and the survival of their predators, to estimate basic parameters of a Lotka-Volterra model. We found that the intrinsic growth rate of algae, the survival rate of predators, and the per-capita predation rate, all varied with salinity and algal strain. Significant interactions between strain and salinity further revealed that these ecological responses to salinity are evolvable. Together with correlations between demographic parameters across salinity, this suggests that predation may influence the evolution of salinity tolerance curves, blurring the line between the fundamental and realized niches.

ecology↗

bioRxiv2025

Environmental complexity constrains evolutionary adaptation across taxa

Complex environments combining multiple stressors are the new norm worldwide. Adaptive evolution will be critical to population persistence under these combined challenges, but how environmental complexity affects the pace of evolution remains poorly understood. Using a meta-experimental evolution approach, we exposed 14 species, from bacteria to unicellular eukaryotes and plants, to single stressors and their pairwise combinations for multiple generations, while keeping the overall stress level comparable. Populations evolving under combined stressors tended to have lower fitness increase in the selective environments, higher fitness reductions in the control environment, and shallower relation between initial maladaptation and fitness gain, than under single stressors. However, these responses varied with species and stressor type. Accounting for such constraints on evolutionary dynamics should prove crucial for the management of biodiversity. Significance StatementA pressing challenges for modern science and society in the face of ongoing global change is understanding what limits the capacity of living organisms to adapt to complex environments combining multiple stressors. To answer to this question, we conducted a large-scale meta-experimental evolution design across a diversity of organisms, exposing them for multiple generations to either single or combined-stress treatments. Combined stressors led to less adaptive fitness gain than single stressors, and imposed additional costs through reduced fitness in non-stressful conditions. This unique combination of meta-experimental approach with a careful distinction between environmental complexity and overall stress allowed us to gain robust quantitative evidence on how environmental complexity can impact the pace of evolution.

evolutionary biology↗

bioRxiv2024

Linking selection to demography in experimental evolution of active death in a unicellular organism

Deciphering how natural selection emerges from demographic differences among genotypes, and reciprocally how evolution affects population dynamics, is key to understanding population responses to environmental stress. This is especially true in non-trivial ecological scenarios, such as programmed cell death (PCD) in unicellular organisms, which can lead to massive population decline in response to stress. To understand how selection may operate on this trait, we exposed monocultures and mixtures of two closely related strains of the microalga Dunalliela salina, one of which induces PCD, to multiple cycles of hyper-osmotic shocks, and tracked demography and selection throughout. Population dynamics were consistent between mixtures and monocultures, suggesting that selection on PCD does not involve strong ecological interactions. The PCD-inducing strain was maintained throughout the experiment despite an initial decline, by a combination of fast population rebound following each decline, and density-dependent competition dynamics near the stationary phase that were independent of these initial population fluctuations. As result of PCD maintenance, population decline in response to environmental stress was not counter-selected in our experiment, but persisted over 13 cycles of salinity. Our results highlight how analysing the demographic underpinnings of fitness and competition can shed light on the mechanisms underlying selection and eco-evolutionary dynamics.

evolutionary biology↗

bioRxiv2022

Glucose oxidation and nutrients availability drive neural crest development

Bioenergetic metabolism is a key regulator of cellular function and signaling activity but the exact roles of nutrient utilization and energy production in embryonic development remain unknown. Here we investigated the metabolic pathways and deciphered the role of carbon metabolism required for the development of neural crest cells (NCC), a migratory stem cell population of the vertebrate embryo. We uncovered that glucose oxidation constitutes the prominent metabolic signature of trunk NCC and supports their delamination, migration, and proliferation. Additionally, we found that glycolysis, mitochondrial respiration and the pentose phosphate pathway are all mobilized downstream of glucose uptake. These metabolic pathways do not support specific cellular processes but cooperate and are integrated to accomplish epithelium-to-mesenchyme transition, adhesion, locomotion and proliferation. Moreover, using different nutrient supplies (glucose vs. pyruvate) we show that glucose is crucial to modulate NCC migration and adaptation to environmental stiffness, control NCC stemness and drive their fate decisions through regulation of specific gene expression. Our data establish that NCC development is instructed by metabolic cues that mobilize defined metabolic pathways cooperating together in response to nutrient availability. SUMMARY STATEMENTHere we show that neural crest cell migration and fate decisions rely primarily on glucose oxidation for energy production and mobilize multiple cooperating metabolic pathways for their biosynthetic needs and execution of gene programs.

developmental biology↗