Biology subjects

Huet, M.

Publications and source records attributed to Huet, M..

3 recordsLinked to original sources

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↗

bioRxiv2023

The macronuclear genomic landscape within Tetrahymena thermophila

The extent of intraspecific genomic variation is key to understanding species evolutionary history, including recent adaptive shifts. Intraspecific genomic variation remains poorly explored in eukaryotic microorganisms, especially in the nuclear dimorphic ciliates, despite their fundamental role as laboratory model systems and their ecological importance in many ecosystems. We sequenced the macronuclear genome of 22 laboratory strains of the oligohymenophoran Tetrahymena thermophila, a model species in both cellular biology and evolutionary ecology. We explored polymorphisms at the junctions of programmed eliminated sequences, and reveal their utility to barcode very closely related cells. As for other species of the genus Tetrahymena, we confirm micronuclear centromeres as gene diversification centres in T. thermophila, but also reveal a two-speed evolution in these regions. In the rest of the genome, we highlight recent diversification of genes encoding for extracellular proteins and cell adhesion. We discuss all these findings in relation with ciliates ecology and cellular characteristics. Impact StatementThis is the first study of population genomics in the ciliate Tetrahymena thermophila. This bacterivore species plays an important role in aquatic trophic chains and is widely used as a model in cell and molecular biology, ecology, evolution or toxicology. As all ciliates, it contains a germline micronucleus and a somatic macronucleus. Sequencing of the macronucleus reveals that the centromeric region of the micronucleus are simultaneously a region of new gene diversification, as observed in other Tetrahymena species, and a region containing highly conserved genes. The results also confirm that the formation of the macronucleus from the micronucleus is highly imprecise. Interestingly, this process generates a genomic barcode that can discriminate cells derived from a given sexual reproduction event, allowing to study more finely population dynamics/history in nature. Data summaryAll data are fully provided in Supplementary Materials. The raw data of the 22 Tetrahymena genomes have been deposited in the Sequence Read Archive (https://www-ncbi-nlm-nih-gov.inee.bib.cnrs.fr/bioproject/PRJNA1012331). Accession numbers are listed in Table S1 (available in the online version of this article).

genomics↗

bioRxiv2019

Transgenerational dispersal plasticity and its fitness consequences are under genetic control

Phenotypic plasticity, the ability of one genotype to produce different phenotypes in different environments, plays a central role in species response to environmental changes. Transgenerational plasticity (TGP) allows the transmission of this environmentally-induced phenotypic variation across generations, and can influence adaptation. To date, the genetic control of TGP, its long-term stability, and its potential costs remain largely unknown, mostly because empirical demonstrations of TGP across many generations in several genetic backgrounds are scarce. Here, we examined how genotype determines the TGP of dispersal, a fundamental process in ecology and evolution. We used an experimental approach involving ~200 clonal generations in a model-species of ciliate to determine if and how TGP influences the expression of dispersal-related traits in several genotypes. Our results show that morphological and movement traits associated with dispersal are plastic, and that these modifications are inherited over at least 35 generations. We also highlight that genotype modulates the fitness costs and benefits associated with plastic dispersal strategies. Our study suggests that genotype-dependent TGP could play a critical role in eco-evolutionary dynamics as dispersal determines gene flow and the long-term persistence of natural populations. More generally, it outlines the tremendous importance that genotype-dependent TGP could have in the ability of organisms to cope with current and future environmental changes.\n\nSignificanceThe genetic control of the transgenerational plasticity is still poorly understood despite its critical role in species responses to environmental changes. We examined how genotype determines transgenerational plasticity of a complex trait (i.e., dispersal) in a model-species of ciliate across ~200 clonal generations. Our results provide evidence that plastic phenotypic variation linked to dispersal is stably inherited over tens of generations and that cell genotype modulates the expression and fitness cost of transgenerational plasticity.

evolutionary biology↗