Biology subjects

Salle, A.

Publications and source records attributed to Salle, A..

7 recordsLinked to original sources

bioRxiv2025

From forest decline to salvage logging: cascading impacts on saproxylic beetle diversity

Understanding the cascading effects of forest decline on saproxylic communities is fundamental for optimizing the management of disturbed forests toward biodiversity conservation objectives. We postulated that the nature and intensity of cascading pathways would vary along decline gradients, encompassing stages from stand decline to mortality and subsequent salvage logging, as mediated by shifts in habitat conditions and resource availability. This study was conducted across three representative European forest contexts: fir forests in the French Pyrenees, spruce forests in the Bavarian Alps, and oak forests in the lowlands of the Loire Valley. Within these systems, we assessed how the taxonomic and functional -diversity of saproxylic beetles responded to variations in both the diversity and density of deadwood and tree-related microhabitats (TreMs). Our analyses identified key cascading effects of stand decline and mortality that were shaped by the considered beetle guild and by the forest type, reflecting tree species-specific disturbance legacies. Stand decline and mortality produced distinct responses within saproxylic beetle assemblages, as different successional guilds preferentially utilized either dying or dead trees. The overall influence of decline processes was positive in conifer-dominated forests. TreMs played a central role in mediating cascading processes structuring saproxylic beetle communities throughout the forest decline continuum. The increase in TreM heterogeneity associated with stand decline or mortality enhanced saproxylic diversity, with exposed wood and trunk injuries identified as particularly influential microhabitats. Snags and large deadwood elements, especially in spruce forests, and deadwood diversity further contributed to sustaining high levels of beetle diversity. Conversely, salvage logging exerted detrimental effects on numerous guilds, primarily through reductions in TreM diversity, decreased TreM trait dispersion, and the depletion of saproxylic TreMs. Given the pronounced context dependency of the processes driving these cascading community dynamics, and considering the increasing frequency, severity, and spatial extent of forest disturbances and global forest decline, it is imperative to integrate this complexity into management and conservation frameworks. Addressing these mechanisms with greater precision will be critical for maintaining functional biodiversity within rapidly changing forest ecosystems.

ecology↗

bioRxiv2025

Preventing unintentional bat captures in canopy traps used for insect surveys

There is growing interest in deploying insect traps in forest canopies for ecological research, invasive species surveillance, and biodiversity monitoring. However, forest canopies also harbor a diverse and abundant bat community, which may be incidentally trapped and killed by these devices. In this study, we investigated the impact of flight interception traps and multi-funnel traps deployed in oak canopies on incidental bat captures, and evaluated whether trap modifications could reduce this bycatch. We also examined how these modifications influenced the species richness, abundance, and mean body size of several beetle taxa, including Buprestidae, Cerambycidae, Cetoniinae, and Scolytinae. Both trap types captured bats. Flight interception traps accidentally caught seven species - Myotis bechsteinii, Myotis daubentonii, Myotis mystacinus, Nyctalus noctula, Nyctalus leisleri, Plecotus auritus, and Pipistrellus pipistrellus - with an average of 0.42 bats per trap. Multi-funnel traps primarily caught males of P. pipistrellus, with an average of 0.29 bats per trap. Adding a 13-mm mesh above the collection container significantly reduced bat bycatch to 0.02 and 0.05 bats per trap in flight interception traps and multi-funnel traps, respectively. This modification had no significant effect on insect species richness or mean body size, although it did reduce Cerambycidae and Scolytinae abundance in black multi-funnel and flight interception traps, respectively. This was likely due to more frequent clogging by twigs and leaves. We recommend modifying flight interception and multi-funnel traps deployed in forest canopies to prevent unintentional harm to protected bat species.

ecology↗

bioRxiv2024

Disruption of the epigenetic regulator BAP1 drives chromatin remodeling leading to the emergence of cells with breast cancer stem cell properties and aberrant glycosylation.

BackgroundEpigenetic regulator genes play critical roles in controlling cell identity and are frequently disrupted in breast cancers, suggesting a key driver role in this disease and its associated phenotypes. However, specific epigenetic drivers (epidrivers) of mammary cell plasticity and their mechanistic contributions to this phenotype are poorly characterized. MethodsTo identify potential epidrivers of the emergence of mesenchymal breast cancer stem cell-like phenotypes in non-tumorigenic mammary cells, we employed a CRISPR/Cas9 loss-of-function screening strategy targeting epigenetic regulator genes. This approach was followed by an in-depth validation and characterization of epigenomic, transcriptomic, proteomic and phenotypic changes resulting from the disruption of the putative epidriver gene BAP1. ResultsOur investigation revealed that loss of the histone deubiquitinase BAP1 impacts cellular processes associated with breast cancer cell plasticity such as epithelial-to-mesenchymal transition (EMT) and actin cytoskeleton organization. In addition, we unveiled that BAP1 loss resulted in an overall less permissive chromatin and downregulated gene expression, impacting programs that control cellular glycosylation and leading to decreased glycan abundance and complexity. BAP1 rescue restored the expression of several deregulated genes in a catalytic activity-dependent manner, suggesting that BAP1-mediated cell identity and glycosylation regulation are largely dependent on its histone deubiquitinase activity. ConclusionsOverall, our results point to BAP1 disruption as a driver of mammary cell plasticity and reveal a novel role of BAP1 as an epigenetic regulator of cellular glycosylation.

cancer biology↗

bioRxiv2024

Intra- and interspecific variations in flight performance of oak-associated Agrilinae (Coleoptera: Buprestidae) using computerised flight mills

AO_SCPLOWBSTRACTC_SCPLOWSeveral Agrilinae species (Coleoptera: Buprestidae) are secondary pests of broadleaf forests, and some of them are also major invasive pests. These thermophilous borers are expected to be favoured by climate change and the global deterioration of forest health, and ultimately expand their range and damage. Flight behaviour and performance of these insects are poorly known despite their critical role in dispersal inside and outside native ranges and their relevance for management purposes. This study aimed to assess intra- and interspecific variability in active flight of several Agrilinae species and effects of sex and mass on this variability to contribute to filling this gap. We assessed the flight performance of eleven species associated with oaks (nine Agrilus, one Coraebus and one Meliboeus) plus one Agrilus species associated with the herbaceous layer. Computer-monitored flight mills were used to measure flight parameters, including periods, durations, distances and velocity in 250 beetles. Overall, flight capacities were rather homogeneous among species, with a dominance of poor flyers and only Coraebus undatus showed outstanding performance. Beetles generally performed several short flight bouts within one trial, and only a few individuals sustained long flight. The maximal total distance covered across multiple assays until death ranged from 170 to 16 097 m depending on the species, with a median between 35 and 966 m (excluding individuals that never flew). On top of this interspecific variability, flight distances also varied greatly among individuals, but were not influenced by sex. Preflight body mass had mixed effects depending on the species, presumably related to different dispersal patterns. In our experimental conditions, most species had limited average dispersal capacities over multiple flight trials. Overall, dispersal over long distances and colonisation events probably depend mainly on a small proportion of individuals which largely exceeded the median performance.

animal behavior and cognition↗

bioRxiv2023

Responses of the hyper-diverse community of canopy-dwelling Hymenoptera to oak decline

O_LIForest decline and dieback are growing phenomena worldwide, resulting in severe, large-scale degradation of the canopy. This can profoundly alter the provision of trophic resources and microhabitats for canopy-dwelling arthropods. C_LIO_LIIn 2019, we assessed the effect of oak decline on the community of canopy-dwelling Hymenoptera. We selected 21 oak stands, and 42 plots, located in three forests in France, presenting contrasting levels of decline. Insects were sampled at the canopy level with green multi-funnel and flight-interception traps. C_LIO_LIWe collected a particularly diverse community of 19,289 insect individuals belonging to 918 taxa, ten larval trophic guilds and five nesting guilds. C_LIO_LIOak decline had no effect on the abundance or richness of the overall community, but significantly reshaped the community assemblages. Decline had contrasting effects depending on the taxa and guilds considered. Specialist parasitoids were more abundant at intermediate levels of decline severity while generalists were negatively affected. Taxa depending on ground-related resources and microhabitats were promoted. Saproxylic taxa were more abundant while xylophagous insects were negatively impacted. C_LIO_LIReduced leaf area index promoted several guilds, and the diversity of the overall community. While an increasing tree mortality rate enhanced the abundance and diversity of deadwood resources, it had negative impacts on several Hymenoptera guilds. Our results suggest that micro-environmental changes at the ground-level due to canopy decline have major cascading effects on the communities of canopy-dwelling Hymenoptera. C_LIO_LIOur study highlights the relevance of studying Hymenoptera communities to investigate the outcomes of disturbances on forest biodiversity. C_LI

ecology↗

bioRxiv2020

Forest decline differentially affects trophic guilds of canopy-dwelling beetles

Context Decline in a context of climate change is expected to induce considerable changes in forest structure, potentially affecting habitat opportunities and trophic resources for numerous species. Nonetheless, the consequences of decline on forest biodiversity have rarely been studied.Aim We aimed to characterize the impact of oak decline on different guilds of canopy-dwelling beetles.Methods Beetles were sampled for three consecutive years in oak stands exhibiting different levels of decline. Several guilds were considered: (i) Buprestidae, (ii) other saproxylic beetles split into wood-boring species and non-wood-boring species, (iii) seed-eating weevils, and (iv) specialist and generalist leaf-eating weevils.Results Overall, decline had positive effects on the abundance and biomass of beetles, though contrasting variations were observed at the species or guild levels. Xylophagous species, especially the main oak-associated buprestids, and other saproxylic species benefitted from decline conditions. However, at odds with the insect performance hypothesis, decline had a positive effect on generalist phyllophagous species, a negative effect on specialist phyllophagous species, and a null effect on seminiphagous species.Conclusion The increase in species richness for saproxylic and phyllophagous beetle communities suggests that decline might promote forest biodiversity. Our results call for further studies to thoroughly assess the functional outcomes of forest decline, and to suggest management strategies for conservation biologists.Key message Decline can affect the structure, resources and microclimates of the forest canopy, and potentially have cascading effects on canopy-dwelling species. Our survey shows that an oak decline can promote saproxylic beetles, especially xylophagous ones, and generalist phyllophagous weevils. However, it negatively affects specialist phyllophagous species and has no effect on seminiphagous weevils.Competing Interest StatementThe authors have declared no competing interest.View Full Text

ecology↗

bioRxiv2018

Salivary proteins of a gall-inducing aphid and their impact on early gene responses of susceptible and resistant host-plant genotypes

Successful plant colonization by parasites requires the circumvention of host defenses, and sometimes a reprogramming of host metabolism, mediated by effector molecules delivered into the host. Using transcriptomic and enzymatic approaches, we characterized salivary glands and saliva of Phloeomyzus passerinii, an aphid exhibiting an atypical feeding strategy. Plant genes responses to salivary extracts of P. passerinii and Myzus persicae were assessed with poplar protoplasts of a susceptible and a resistant genotype, and in a heterologous Arabidopsis system. We predict that P. passerinii secretes a highly peculiar saliva containing effectors potentially interfering with host defenses, biotic stress signaling and plant metabolism, notably phosphatidylinositol phosphate kinases which seemed specific to P. passerinii. Gene expression profiles indicated that salivary extracts of M. persicae markedly affected host defenses and biotic stress signaling, while salivary extracts of P. passerinii induced only weak responses. The effector-triggered susceptibility was characterized by downregulations of genes involved in cytokinin signaling and auxin homeostasis. This suggests that P. passerinii induces an intracellular accumulation of auxin in susceptible host genotypes, which is supported by histochemical assays in Arabidopsis. This might in turn affect biotic stress signaling and contribute to host tissue manipulation by the aphid.

ecology↗