Biology subjects

Pinel, S.

Publications and source records attributed to Pinel, S..

3 recordsLinked to original sources

bioRxiv2026

Life-history traits may buffer genetic erosion under isolation in mountain sky-island systems

Sky-island systems provide natural case studies for understanding how geography and Quaternary history shape genomes, phenotypes and life-history traits in mountain endemics. We investigated Xatartia scabra (Apiaceae), a monotypic scree specialist plant species restricted to sky-island summits in the eastern Pyrenees, by integrating population genomics with abiotic condition-informed distribution modeling. Using a ddRAD-seq-like protocol (nGBS), we genotyped 125 individuals (21,970 SNPs), and applied species distribution modeling to identify suitable environmental conditions from the Last Glacial Maximum to 2100. Genetic analyses revealed unexpected genetic "resilience", with moderate genome-wide diversity (HE = 0.17, Ho = 0.15) and low inbreeding (FIS = 0.07), despite small census sizes and strong isolation. Significant overall genetic differentiation (FST = 0.16), with pronounced summit-level structure and strong isolation-by-distance, supports deep valleys as barriers to gene flow. Abiotic niche reconstructions recovered extensive Heinrich Stadial 1 connectivity (+ 58,4% relative to present), followed by postglacial loss of suitable habitats at lower elevations and increasing fragmentation; projections under climate change forecast contraction (-61,2%, relative to present) of climatic suitability, expected to intensify drift in small, isolated populations. Demographic inferences align with this narrative, indicating postglacial decline in effective population sizes. Taken together, genetic, climatic, and demographic evidence supports a transition from historically connected lowland corridors to modern sky islands where distance-limited drift dominates. The maintenance of moderate genetic diversity and low inbreeding under strong isolation suggests that X. scabra may have evolved life-history strategies including outcrossing and monocarpy that allow limiting genetic erosion in such extreme and fragmented environments.

genomics↗

bioRxiv2025

Predicting spatiotemporal bioclimatic niche dynamics of endemic Pyrenean plant species under climate change: how much will we lose?

Species distributions are shifting under global change, with mountain ecosystems among the most vulnerable. In such landscapes, ability to track changing conditions is limited, threatening narrowly distributed species. As a mountain biodiversity hotspot in southwestern Europe, the Pyrenees harbors many such species, making it a key case study for climate vulnerability assessments. This study implements a bioclimatic niche modeling pipeline to evaluate climate change impact on endemic Pyrenean plant species by 2100. Objectives are to (i) map current bioclimatic niche suitability, (ii) forecast its future spatial dynamics, and (iii) identify potential climate refugia for conservation. Species occurrences were combined with 19 bioclimatic variables (1x1 km resolution) to characterize bioclimatic niche suitability, using an ensemble modeling approach integrating five algorithms (MaxEnt, Generalized Linear Model, Generalized Additive Model, Gradient Boosting Machine, and Random Forest). Their future spatiotemporal dynamics were projected under four climate scenarios (Shared Socioeconomic pathways 126, 245, 370, 585) for four successive periods spanning 2021 to 2100. By 2100, 69% of endemic species are projected to lose over 75% of their bioclimatic niche, and half to face complete losses under high-emission scenarios. Only two species may gain suitable areas, highlighting the need for species-specific conservation strategies. Bioclimatic niches are projected to shift by [~]180 m upslope and [~]3 km in latitude on average, with areas of highest multi-species suitability, referred to as bioclimatic hotspots, becoming restricted to elevation above 2000 m. These trends intensify after 2041-2060 period, reflecting escalating climate pressures as the century progresses. Our findings highlight the profound threat climate change may pose to endemic Pyrenean flora, with widespread bioclimatic niche losses projected by the centurys end and high elevation refugia emerging as key conservation priorities. Anticipating these shifts and integrating them into conservation planning will be crucial to mitigating high-elevation biodiversity loss in a rapidly changing world.

ecology↗

bioRxiv2024

Exploiting the inherent promiscuity of the acyl transferase of the stambomycin polyketide synthase for the mutasynthesis of analogues

The polyketide specialized metabolites of bacteria are attractive targets for generating analogues, with the goal of improving their pharmaceutical properties. Here, we aimed to produce C-26 derivatives of the giant anti-cancer stambomycin macrolides using a mutasynthesis approach, as this position has been shown previously to directly impact bioactivity. For this, we leveraged the intrinsically broad specificity of the acyl transferase domain (AT12) of the modular polyketide synthase (PKS), which is responsible for the alkyl branching functionality at this position. Feeding of a panel of synthetic and commercially available dicarboxylic acid mutasynthons to an engineered strain of Streptomyces ambofaciens (Sa) deficient in synthesis of the native -carboxyacyl-CoA extender units, resulted in six new series of stambomycin derivatives as judged by LC-HRMS and NMR. Notably, the highest product yields were observed for substrates which were only poorly accepted when AT12 was transplanted into a different PKS module, suggesting a critical role for domain context in the overall functioning of PKS proteins. We also demonstrate the superiority of this mutasynthesis approach - both in terms of absolute titers and yields relative to the parental compounds - in comparison to the alternative precursor-directed strategy in which monoacid building blocks are supplied to the wild type strain. We further identify a malonyl-CoA synthetase, MatB_Sa, with specificity distinct from previously identified promiscuous enzymes, making it a useful addition to a mutasynthesis toolbox for generating atypical, CoA activated extender units. Finally, we show that two of the obtained (deoxy)-butyl-stambomycins exhibit antibacterial and antiproliferative activities similar to the parental stambomycins, while an unexpected butyl-demethyl congener is less potent. Overall, this works confirms the interest of biosynthetic pathways which combine a dedicated route to extender unit synthesis and a broad specificity AT domain for producing bioactive derivatives of fully-elaborated complex polyketides.

synthetic biology↗