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Phenotypic Plasticity

In response to environmental changes, organisms have three main strategies : (1) they can relocate to more favorable habitats, (2) they can exhibit suitable traits if they possess information during their developmental stage about the environment they will encounter during reproduction, or (3) they can adapt by the evolution of phenotypic plasticity.

Our research has been focused on elucidating natural selection when individuals rely on environmental information inherited from preceding generations. When adapting to fluctuating environments, transgenerational plasticity (such as maternal effects) might evolve as long as mothers or other direct ancestors experience predictable environments. However, the evolution of transgenerational plasticity might be hindered by genetic conflicts, such as sexual or parent-offspring conflicts, leading natural selection to favor bet-hedging strategies instead. Recently, we’ve delved into the study of adaptation in scenarios where multiple environmental variables can either guide or mislead organisms in developing optimal phenotypes.

Reference publications : How differing modes of transgenerational inheritance affect population viability in fluctuating environments, Slower environmental change hinders adaptation from standing genetic variation, Adaptation to temporally fluctuating environments by the evolution of maternal effects.

In collaboration with the teams of : Stephen Proulxat the University of California in Santa Barbara, and Christian Braendle at the Institute de Biologie Valrose in Nice.

Multivariate Phenotypic Evolution

Phenotypic evolution should be considered in the context of the whole organism, as organisms are more than just assemblages of genetically or environmentally distinct traits. Predicting adaptive phenotypic evolution then depends on how variable selection gradients are and on the constancy of genetic correlations among the constituent traits of the multivariate phenotype.

Experiments from the lab have demonstrated that short-term phenotypic evolution in a new environment is predictable when evolution predominantly occurs along trait-combination dimensions with genetic variation. However, predicting the evolution of phenotypic plasticity remains challenging due to intricate pleiotropic and linkage disequilibrium dynamics. Current research is focused on forecasting phenotypic evolution based on the analysis of population genomics data during experimental evolution.

Reference publications : Selection and the direction of phenotypic evolution, Variation in mutational (co)variances, Experimental evolution reveals natural selection on standing genetic variation.

In collaboration with the teams of : Charles Baer at the University of Florida in Gainsville, and Matthew Rockman at the New York University.

Self-fertilization and Outcrossing

Numerous organisms, such as C. elegans, employ self-fertilization and outcrossing (partial selfing) as their reproductive strategies. Partial selfing is anticipated to exert significant effects on the preservation of genetic diversity and the process of adaptation to changing environments.

We’ve investigated the influence of partial selfing on adaptation and observed that it facilitates the removal of harmful genetic variation while concurrently preserving greater genetic diversity at loci under balancing selection. Nevertheless, trade-offs between traits expressed in hermaphrodites during selfing or outcrossing can constrain adaptation. A recent area of focus involves investigating the developmental underpinnings of these trade-offs, particularly the interplay between self-spermatogenesis and selfing behavior versus oogenesis and outcrossing behavior.

Reference publications : Partial selfing can reduce genetic loads while maintaining diversity, Reproductive assurance drives transitions to self-fertilization in experimental Caenorhabditis elegans, The opportunity for balancing selection in experimental populations of Caenorhabditis elegans.

In collaboration with the teams of : Stephen Proulxat the University of California in Santa Barbara, Patrick Phillips at the University of Oregon in Eugene, Hinrich Schulenburg at Kiel University, and Christian Braendle at the Institute de Biologie Valrose in Nice.

Recombination Landscapes

Modifiers that elevate recombination rates should be (indirectly) favored by natural selection when they reduce interference between harmful and advantageous gene variants. By augmenting recombination rates, these modifiers will enhance the variance in fitness, consequently increasing the potential for adaptation to changing environments.

Our research has revealed that indirect selection of modifiers can be attributed to selective interference among gene variants in its proximity. Nevertheless, adaptation to changing environments relies on the distribution of fitness heritability across the genome, which can lead to contrasting evolutionary dynamics regarding recombination modifiers. Our current research examines how the effects of recombination modifiers on adaptation, whether local or global, are influenced by factors such as reproduction mode and population structure.

Reference publications : rec-1 loss of function increases recombination in the central gene
clusters at the expense of autosomal pairing centers
. The relative strength of selection on modifiers of genetic architecture under migration load. Polygenicity and epistasis underlie fitness-proximal traits in the Caenorhabditis elegans multiparental experimental evolution (CeMEE) panel.

In collaboration with the teams of : Denis Roze at the Biology Research Station in Roscoff, Stephen Proulxat the University of California in Santa Barbara, and Matthew Rockman at the New York University.

Collembola and Fruit Flies

Our work before establishing an independent team investigated similar topics using Collembola and especially the fruit flies as model systems. Some of our reference publications from this period are : A simple genetic basis of adaptation to a novel thermal environment results in complex metabolic rewiring in Drosophila, Contesting the evidence for non-adaptive plasticity, From individuals to populations : How intraspecific competition shapes thermal reaction norms, Within species variation in longterm trajectories of growth, fecundity and mortality in the Collembola Folsomia candida, and Variation in the reversibility of evolution.