Biology subjects

Ernande, B.

Publications and source records attributed to Ernande, B..

5 recordsLinked to original sources

bioRxiv2026

Filling a metabolism data gap in marine fish reveals dual pace-of-life and reproductive strategy axes

Resting metabolic rate, the basal energy required for an organism's maintenance, is central to predicting the eco-evolutionary consequences of environmental and anthropogenic pressures on marine ectotherms. Yet, direct measurements remain extremely scarce, covering less than 1% of marine fish species. Building on the Pace Of Life Syndrome (POLS) hypothesis, which posits a positive correlation between metabolism and life-history speed, we inferred temperature- and mass-specific resting metabolic rate for 18,214 fish species (16,998 Teleostei and 1,216 Elasmobranchii). Estimates were derived from relationships with 15 functional traits and phylogeny using phylogenetic structural equation modelling, a novel approach combining phylogenetic comparative methods with structural equation models. Cross-validations indicated high predictive performance, although some clades require cautious interpretation due to limited empirical data. In line with expectations from life-history theory, ecological niche and morphology, species with the highest metabolic rates were small, narrow, shallow-bodied, and long-jawed pelagic fish with high mortality, short lifespan and rapid growth - traits typical of small epipelagics. The metabolic rate variation aligned with the slow-fast life-history continuum, supporting the POLS hypothesis, but was equally explained by reproductive strategy: highly fecund, fast species exhibited the highest metabolic rate independent of mass and temperature, whereas low-fecundity slow species had the lowest. By filling a critical physiological data gap, our dataset provides a foundation to test long-standing ecological and evolutionary hypotheses such as POLS, and offers a powerful resource to improve models of species and community responses to climate change and exploitation, ultimately supporting physiology-informed ecosystem management.

ecology↗

bioRxiv2026

Development and parameterisation of a size-structured multispecies bioeconomic model integrating consumer demand

A high proportion of the world's population relies on marine fisheries as a source of food and employment, highlighting the need for sustainable exploitation strategies. However, fisheries management commonly relies on single-species models that overlook ecological interactions and economic trade-offs, which may lead to stocks being exploited above sustainable levels. To address this gap, we developed a novel size-structured, multispecies bioeconomic module integrated within the spatially explicit, individual-based OSMOSE ecosystem model. OSMOSE represents exploited fish communities in which individuals interact through opportunistic, size-dependent predator-prey interactions which are explicitly incorporated into the bioeconomic framework. The bioeconomic model accounts for multiple species and size classes, allowing for size-dependent market prices. Fishing costs and profits are represented using an extension of the Gordon-Schaefer model to multiple interacting species, while consumer demand is modelled using a nested Dixit-Stiglitz utility function with three levels of constant elasticity of substitution for fish commodity, species and size classes. We present a method for estimating parameters for the bioeconomic module when empirical estimates are unavailable, using the North Sea OSMOSE configuration, which comprises 15 species. Our method successfully estimated the six bioeconomic parameters required to operationalise the model. Results indicate that differences in cost parameters were primarily associated with variability in species biomass rather than fishing gear, while fish prices were more strongly influenced by consumer's demand than by availability. This framework provides a basis for assessing the economic consequences of alternative climate change scenarios and supporting sustainable fisheries management.

ecology↗

bioRxiv2024

Ecotype formation in the European anchovy fuelled by structural variants of different origins and genetic interactions with a southern lineage

The formation of ecotypes is shaped by mechanisms that reduce gene flow through complex interactions between ecological, historical, and genomic factors. In the European anchovy (Engraulis encrasicolus), marine and coastal ecotypes have been identified in the North-East Atlantic and Mediterranean Sea, yet the genomic basis of their divergence remains unclear. Here, we present the first genome-scale analysis of this species complex, integrating whole-genome sequencing (WGS) and RAD-seq data from populations across its distribution range. In addition to the marine and coastal ecotypes, we identify a previously undetected lineage which is present in southern Morocco, the Canary Islands and even in South Africa. This southern Atlantic lineage exhibits a gradient of admixture with northern populations near the Atlantic-Mediterranean transition zone. Genomic differentiation landscapes reveal large regions of high linkage disequilibrium, likely corresponding to thirteen structural variants (SVs) segregating within or between the lineages. Notably, three of the six SVs contributing to the gene flow barrier between northern ecotypes originated in the southern lineage, supporting a partially shared evolutionary history between the coastal ecotype and the southern lineage. Our findings suggest that anchovy ecotype divergence has been shaped by a combination of ancient structural variation, admixture, and local adaptation. This study highlights how SVs that arose between geographically isolated lineages can act as key genetic elements in ecotype formation, reinforcing reproductive isolation through distinct evolutionary pathways.

evolutionary biology↗

bioRxiv2023

Ev-OSMOSE: An eco-genetic marine ecosystem model

In the last decade, marine ecosystem models have been increasingly used to project interspecific biodiversity under various global change and management scenarios, considering ecological dynamics only. However, fish populations may also adapt to climate and fishing pressures, via evolutionary changes, leading to modifications in their life-history that could either mitigate or worsen, or even make irreversible, the impacts of these pressures. Building on the multispecies individual-based model Bioen-OSMOSE, an eco-evolutionary fish community model, Ev-Osmose, has been developed to account for evolutionary dynamics together with physiological and ecological dynamics in fish diversity projections. A gametic inheritance module describing the individuals genetic structure has been implemented. The genetic structure is defined by finite numbers of loci and alleles per locus that determine the genetic variability of growth, maturation and reproductive effort. Climate change and fishing activities will generate selection pressures on fish life-history traits that will respond through microevolution. This paper is an overview of the Ev-OSMOSE model. To illustrate the ability of the Ev-OSMOSE model to represent realistic fish community dynamics, genotypic and phenotypic traits mean and variance and consistent evolutionary patterns, we applied the model to the North Sea ecosystem. The simulated outputs are confronted to observed data of commercial catch, maturity ogives and length at age and to estimates of biomass for each modeled species. In addition to the evaluation of their mean value, the emerging traits variability is confronted to length-at-age and maturity data. To ensure the consistency of genetic inheritance and the resulting evolutionary patterns, we assessed the transmission of traits genotypic value across cohorts. Overall, the state of the modelled ecosystem was convincing at all these different biological levels. These results open perspectives for using Ev-OSMOSE in different marine regions to project the eco-evolutionary impact of various global change and management scenarios on different biological levels.

ecology↗

bioRxiv2023

Bioen-OSMOSE: A bioenergetic marine ecosystem model with physiological response to temperature and oxygen

O_LIMarine ecosystem models have been used to project the impacts of climate-induced changes in temperature and oxygen on biodiversity mainly through changes in species spatial distributions and primary production. However, fish populations may also respond to climatic pressures via physiological changes, leading to modifications in their life history that could either mitigate or worsen the consequences of climate change. C_LIO_LIBuilding on the individual-based multispecies ecosystem model OSMOSE, Bioen-OSMOSE has been developed to account for high trophic levels physiological responses to temperature and oxygen in future climate projections. This paper presents an overview of the Bioen-OSMOSE model, mainly detailing the new developments. These consist in the implementation of a bioenergetic sub-model that mechanistically describes somatic growth, sexual maturation and reproduction as they emerge from the energy fluxes sustained by food intake under the hypotheses of a biphasic growth model and plastic maturation age and size represented by a maturation reaction norm. These fluxes depend on temperature and oxygen concentration, thus allowing plastic physiological responses to climate change. C_LIO_LITo illustrate the capabilities of Bioen-OSMOSE to represent realistic ecosystem dynamics, the model is applied to the North Sea ecosystem. The model outputs are confronted with population biomass, catch, maturity ogive, mean size-at-age and diet data of each species of the fish community. A first exploration of current species spatial variability in response to temperature or oxygen is presented in this paper. The model succeeds in reproducing observations, with good performances for all indicators. C_LIO_LIThis new model development opens the scope for new fields of research such as the exploration of seasonal or spatial variation in life history in response to biotic and abiotic factors at the individual, population and community levels. Understanding such variability is crucial to improve our knowledge on potential climate change impacts on marine ecosystems and to make more reliable projections under climate change scenarios. C_LI

ecology↗