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During my first post-doc, I worked on the impact of environmental autocorrelation on population dynamics and evolution of the halotolerant microalgae Duneliella salina. Temporal autocorrelation is defined by the level of similarity between a variable and itself at two successive time points and determines the level of environmental predictability.
I replicated nearly 1000 independent Dunaliella salina lines subjected to various salinity treatment (constant or variable with different degree of temporal autocorrelation) and used state space modelling to analyze their population dynamics . We showed that temporal autocorrelation increases growth rates (then population size) mean and decrease its variance, decreasing by 50% the extinction risk when environmental variation is autocorrelated. It is explained by a phenotypic memory of the past environment, mediated by the production and excretion rates of glycerol allowing osmoregulation.
I then followed the frequencies of two strains in competition with amplicon sequencing of two DNA barcodes, and showed that environmental variance, but also autocorrelation had large impacts on the average selection coefficient. The reaction norm of selection coefficients against constant salinity yielded accurate predictions for the mean selection coefficient in a fluctuating environment. This selection reaction norm was in turn well predicted by environmental tolerance curves, with population growth rate against salinity. However, both the selection reaction norm and tolerance curve underestimated the variance in selection caused by random environmental fluctuations.
People involved: Luis-Miguel Chevin (supervisor), Daphné Grulois, Enrique Ortega-Aboud, Christelle Leung, Nicolas Leurs (M1)
During my PhD, I used mathematical models (population genetics, quasi linkage equilibrium approximations...) and multilocus, individual-based simulations to analyze the effects of the interaction between genetics factors and environmental heterogeneity on the evolution of haploid diploid life cycles. We highlighted that temporal fluctuations of haploids and diploids fitnesses should allow the maintenance of haploid diploid life cycles, while spatial ecological differentiation should lead to speciation between haploids and diploids.
I also tried to test experimentally the ploidy consequences on adaptation and speciation using the budding yeast Saccharomyces cerevisiae. I tried to compare the mutation load of haploids and diploids on isogenic haploid and diploid mutator lines, but faced a diploidisation of the haploid strains. I then studied the evolution of post zygotic isolation in haploids and diploids by crossing isolated populations of yeast and measuring the hybrids fitness (F1 2n, F1 n, F2 2n) through time, but most of the populations I used lost their ability to perform sex and we lacked data to get quantitative insights in the hybrid breakdown.
People involved: Denis Roze (supervisor), Thomas Lenormand, Jean-Nicolas Jasmin, Michael Scott (collaborators), Justine Serrusier, Anthea Bourris (BTS )
I applied theoretical results for the set of sustainable outcomes in a dynamic bargaining problem to the research of the better strategy allowing ecological and economic sutainability for two threatened fisheries: the patagonian toothfish (Dissostichus eleginoides) and the chilean hoki (Macruronus magellanicus). I computed the Maximin, maximal yield allowing the conservation of minimal thresholds (spawning biomass, fishing mortality, catch per unit effort), and investigate the effect of constant and variable Total Allowable Catch policies.
People involved: Pedro Gajardo (supervisor), Héctor Ramírez
I studied how one hour of light pulse affects the circadian rhythms of individual honeybees maintained in dark. We produced the first Light Phase Response Curve for Apis mellifera. This response curve provides a quantitative context to analyse the effect of different substances on sleep. I also develop standardized measures of bee activity after an anaesthetics injection (and decided to stop working on animals in labs).
People involved: Guy Warman (supervisor), Nicola Ludin, James Cheeseman
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