Biology subjects

Bourret, A.

Publications and source records attributed to Bourret, A..

3 recordsLinked to original sources

bioRxiv2025

Past environments modulate response to fluctuating temperatures in a marine fish species

The rise in ocean temperatures predicted due to the global warming will impact the survival and structure of various marine organisms, in particular ectothermic organisms. Phenotypic plasticity enables species to cope with environmental changes, providing a vital buffer for evolutionary changes. Yet, the dynamics and the molecular mechanisms underpinning these plastic responses remain largely unexplored. Here, we assessed the impact of acclimation environment on organisms capacity for thermal plasticity. We conducted a genome-wide transcriptomic analysis on the Acadian redfish, S. fasciatus, exposed to four temperatures (2.5, 5.0, 7.5 and 10.0 ) over a long-term period (up to 10 months) followed by an acute temperature change (24 hours), simulating natural fluctuation condition the species could encounter. Our results showed a dynamic transcriptional response to temperature involving various genes functions. The rapid response to temperature shifts, coupled with the sustained expression of specific genes over an extended period highlighted the species capacity for plastic response to temperature changes. We also detected a significant effect of the interaction between the long and short terms temperature exposure on gene expression, highlighting the influence of the past environment on response to acute temperature changes. Specifically, fish acclimated to higher temperatures demonstrated an increased stress-related response to environmental fluctuations, as evidenced by both the shape of their reaction norms and the implication of stress-related gene functions. This result suggests that temperature conditions predicted for the near future in the Northwest Atlantic will trigger less adaptive plasticity to environmental fluctuations, highlighting the species vulnerability to ocean warming.

ecology↗

bioRxiv2024

Diving into broad-scale and high-resolution population genomics to decipher drivers of structure and climatic vulnerability in a marine invertebrate

Species with widespread distributions play a crucial role in our understanding of climate change impacts on population structure. In marine species, population structure is often governed by both high connectivity potential and selection across strong environmental gradients. Despite the complexity of factors influencing marine populations, studying species with broad distribution can provide valuable insights into the relative importance of these factors and the consequences of climate-induced alterations across environmental gradients. We used the northern shrimp Pandalus borealis and its wide latitudinal distribution to identify current drivers of population structure and predict the species vulnerability to climate change. Individuals sampled across 24{degrees} latitude were genotyped at high geographic-(54 stations) and genetic-(14,331 SNPs) resolutions to assess genetic variation and environmental correlations. Four populations were identified in addition to finer substructure associated to local adaptation. Geographic patterns of neutral population structure reflected predominant oceanographic currents, while a significant proportion of the genetic variation was associated with gradients in salinity and temperature. Adaptive landscapes generated using climate projections suggest a larger genomic offset in the southern extent of the P. borealis range, where shrimp had the largest adaptive standing genetic variation. Our genomic results combined with recent observations point to the non-recovery in southern regions and an impending vulnerable status in the regions at higher latitude for P. borealis. They also provide rare insights into the drivers of population structure and climatic vulnerability of a widespread meroplanktonic species, which is crucial to understand future challenges associated with invertebrates essential to ecosystem functioning.

genomics↗

bioRxiv2022

Maximizing the reliability and the number of species assignments in metabarcoding studies

The use of environmental DNA (eDNA) for biodiversity assessments has increased rapidly over the last decade. However, the reliability of taxonomic assignments in metabarcoding studies is variable, and affected by the reference databases and the assignment methods used. Species level assignments are usually considered as reliable using regional libraries but unreliable using public repositories. In this study, we aimed to test this assumption for metazoan species detected in the Gulf of St. Lawrence, in the Northwest Atlantic. We first created a regional library with COI barcode sequences including a reliability ranking system for species assignments. We then estimated the accuracy of the public repository NCBI-nt for species assignments using sequences from the regional library, and contrasted assigned species and their reliability using NCBI-nt or the regional library with a metabarcoding dataset and popular assignment methods. With NCBI-nt and sequences from the regional library, Blast-LCA was the most accurate method for species assignments but the proportions of accurate species assignments were higher with Blast-TopHit (>80 % overall taxa, between 70 and 90 % amongst taxonomic groups). With the metabarcoding dataset, the reliability of species assignments was greater using the GSL-rl compared to NCBI-nt. However, we also observed that the total number of reliable species assignments could be maximized using both GSL-rl and NCBI-nt, and their optimal assignment methods, which differed. The use of a two-step approach in species assignments, using a regional library and a public repository, could improve the reliability and the number of detected species in metabarcoding studies.

genetics↗