Biology subjects

ODDOU-MURATORIO, S.

Publications and source records attributed to ODDOU-MURATORIO, S..

3 recordsLinked to original sources

bioRxiv2026

Genetic differentiation between two locations along an ocean/river gradient captures the signature of intragenerational selection in the European eel (Anguilla anguilla)

AO_SCPLOWBSTRACTC_SCPLOWMigration events can act as strong selective filters by spatially sorting individuals according to their migration ability, behaviour, and associated functional traits. The European eel, a panmictic and threatened fish, presents various estuarine migration patterns at juvenile stage (glass eel), ranging from sedentarization in brackish/saltwater of the estuary (non-migrant phenotype) to upstream colonisation of freshwater ecosystems (migrant phenotype). We hypothesize that migration propensity is partly genetically determined in glass eel, and that migration-related genotypes are spatially sorted during estuarine migration. To test these hypotheses, we first collected six pools of individuals over three years at two extreme sites along a gradient from ocean to Adour River tidal limit (Ocean vs. Upstream). Secondly, we collected additional glass eels and phenotypically sorted migrant vs. non-migrant individuals using an experimental device mimicking alternating tidal currents, producing two other pools. Whole genome pool sequencing and analysis of these eight pools generated 18.99 106 SNP variants. Controlling for linked selection through a local score approach, we found five best outlier SNPs with a significant genetic differentiation between Ocean vs. Upstream sites (average FST = 0.21) compared to the pangenomic estimate (FST = 0.0086). These five SNPs were all found in the same gene (gpb2), involved in interferon-mediated antiviral immune responses. We also found 28 best outlier SNPs with a significant genetic differentiation between migrant vs. non-migrant phenotypes (average FST = 0.51). They were located in genes mainly involved in neuronal development, cell migration and tissue remodelling, transcriptional regulation, and metabolic or stress-related processes. Our results support that variation in eel migration propensity is partly genetically determined and that, while panmixia maintains high level of genetic diversity, spatial sorting could promote intra-generational genetic divergence between habitats of European eels. However, the absence of shared genes among the best outliers between in-situ and experimental contrasts suggests a complex and context-dependent genetic control of migration.

evolutionary biology↗

bioRxiv2026

Telomere length can be estimated from fish scales

Telomeres, repetitive DNA sequences at the ends of chromosomes, are increasingly studied as biomarkers of physiological stress as well as ageing processes. In ichthyology, fish scales provide valuable information regarding life history and ageing and are thus often preserved in substantial collections. This study aims to adapt a quantitative Polymerase Chain Reaction (qPCR) method to estimate relative telomere length (RTL) from fish scales archived in such collections. Using the brown trout (Salmo trutta) as a model species, we show that archived scales contain enough DNA to perform qPCR-based RTL measurement. RTLs in scales are on average higher than in fins, however we found no significant correlation between RTL values of both tissues at the individual level. Analysing archived scales originating from the subantarctic Kerguelen Islands introduced brown trout populations, we find substantial variation in RTL between rivers, age classes and body size.

molecular biology↗

bioRxiv2021

Genetic signatures of divergent selection in European beech (Fagus sylvatica L.) are associated with the variation in temperature and precipitation across its distribution range

High genetic variation and extensive gene flow may help forest trees with adapting to ongoing climate change, yet the genetic bases underlying their adaptive potential remain largely unknown. We investigated range-wide patterns of potentially adaptive genetic variation in 64 populations of European beech (Fagus sylvatica L.) using 270 SNPs from 139 candidate genes involved either in phenology or in stress responses. We inferred neutral genetic structure and processes (drift and gene flow) and performed differentiation outlier analyses and gene-environment association (GEA) analyses to detect signatures of divergent selection. Beech range-wide genetic structure was consistent with the species previously identified postglacial expansion scenario and recolonization routes. Populations showed high diversity and low differentiation along the major expansion routes. A total of 52 loci were found to be putatively under selection and 15 of them turned up in multiple GEA analyses. Temperature and precipitation related variables were equally represented in significant genotype-climate associations. Signatures of divergent selection were detected in the same proportion for stress response and phenology-related genes. The range-wide adaptive genetic structure of beech appears highly integrated, suggesting a balanced contribution of phenology and stress-related genes to local adaptation, and of temperature and precipitation regimes to genetic clines. Our results imply a best-case scenario for the maintenance of high genetic diversity during range shifts in beech (and putatively other forest trees) with a combination of gene flow maintaining within-population neutral diversity and selection maintaining between-population adaptive differentiation.

evolutionary biology↗