Biology subjects

Brosse, S.

Publications and source records attributed to Brosse, S..

6 recordsLinked to original sources

bioRxiv2026

Chemosensory ERP Suggest Peripherally Driven Olfactory-Trigeminal Interactions in Healthy Older Adults

The olfactory and intranasal trigeminal systems interact closely, influencing chemosensory perception, yet the mechanisms underlying their interaction remain poorly understood and have been studied mainly in young adults. We aimed to characterize olfactory-trigeminal interactions in aging by comparing electrophysiological and behavioral responses under ipsilateral and contralateral olfactory-trigeminal co-stimulation, to determine the relative contributions of peripheral and central mechanisms. Using chemosensory event-related potentials and a localization task, 44 healthy older adults (66.3 {+/-} 4.6 years; 29 women) were tested under four conditions: pure trigeminal (carbon dioxide; CO2), pure olfactory (2-phenylethanol; PEA), ipsilateral co-stimulation (PEA+CO2 in the same nostril), and contralateral co-stimulation (PEA+CO2 in opposite nostrils). Ipsilateral, but not contralateral olfactory-trigeminal co-stimulation, improved trigeminal localization performance and induced larger late positive component amplitudes. Together, these findings suggest that olfactory-trigeminal interactions are driven primarily by peripheral rather than central mechanisms. This study also provides normative CSERP data for healthy older adults.

neuroscience↗

bioRxiv2022

Species invasiveness and community invasibility of US freshwater fish fauna revealed via trait-based analysis

While biological invasions are recognized as a major threat to global biodiversity, determining species abilities to invade new areas (species invasiveness) and the vulnerability of those areas to invasions (community invasibility) are still poorly understood. Here, we used trait-based analysis to profile invasive species and quantify the community invasibility for >1,800 North American freshwater fish communities. We show that species with higher reproduction rates, longer life spans and larger sizes tend to be more invasive. Community invasibility peaked when the functional distance among native species was high, leaving unoccupied functional space for the establishment of potential invaders. Invasion success is therefore governed by both the functional traits of non-native species determining their invasiveness, and by the functional characteristics of the invaded community determining its invasibility. Considering those two determinants together will allow better predictions of invasions.

ecology↗

bioRxiv2021

Fast processing of environmental DNA metabarcoding sequence data using convolutional neural networks

1The intensification of anthropogenic pressures have increased consequences on biodiversity and ultimately on the functioning of ecosystems. To monitor and better understand biodiversity responses to environmental changes using standardized and reproducible methods, novel high-throughput DNA sequencing is becoming a major tool. Indeed, organisms shed DNA traces in their environment and this "environmental DNA" (eDNA) can be collected and sequenced using eDNA metabarcoding. The processing of large volumes of eDNA metabarcoding data remains challenging, especially its transformation to relevant taxonomic lists that can be interpreted by experts. Speed and accuracy are two major bottlenecks in this critical step. Here, we investigate whether convolutional neural networks (CNN) can optimize the processing of short eDNA sequences. We tested whether the speed and accuracy of a CNN are comparable to that of the frequently used OBITools bioinformatic pipeline. We applied the methodology on a massive eDNA dataset collected in Tropical South America (French Guiana), where freshwater fishes were targeted using a small region (60pb) of the 12S ribosomal RNA mitochondrial gene. We found that the taxonomic assignments from the CNN were comparable to those of OBITools, with high correlation levels and a similar match to the regional fish fauna. The CNN allowed the processing of raw fastq files at a rate of approximately 1 million sequences per minute which was 150 times faster than with OBITools. Once trained, the application of CNN to new eDNA metabarcoding data can be automated, which promises fast and easy deployment on the cloud for future eDNA analyses.

bioinformatics↗

bioRxiv2020

Characterizing the spatial signal of environmental DNA in river systems using a community ecology approach

Environmental DNA (eDNA) is gaining a growing popularity among scientists but its applicability to biodiversity research and management remains limited in river systems by the lack of knowledge about the spatial extent of the downstream transport of eDNA. Here, we assessed the ability of eDNA inventories to retrieve spatial patterns of fish assemblages along two large and species rich Neotropical rivers. We first examined overall community variation with distance through the distance decay of similarity and compared this pattern to capture-based samples. We then considered previous knowledge on individual species distributions, and compared it to the eDNA inventories for a set of 53 species. eDNA collected from 28 sites in the Maroni and 25 sites in the Oyapock rivers permitted to retrieve a decline of species similarity with distance between sites. The distance decay of similarity derived from eDNA was similar, and even more pronounced, than that obtained with capture-based methods (gil-nets). In addition, the species upstream-downstream distribution range derived from eDNA matched to the known distribution of most species. Our results demonstrate that environmental DNA does not represent an integrative measure of biodiversity across the whole upstream river basin but provide a relevant picture of local fish assemblages. Importantly, the spatial signal gathered from eDNA was therefore comparable to that gathered with local capture based methods, which describes fish fauna over a few hundred metres.

ecology↗

bioRxiv2020

Mapping extinction risk in the global functional spectra across the tree of life

Although one quarter of the species of plants and vertebrates are threatened with extinction, little is known about how the potential effect of extinctions on the global diversity of ecological strategies. Using trait and phylogenetic information for more than 75,000 species of plants, mammals, birds, reptiles, amphibians and freshwater fishes, we characterized the global functional spectra of each of these groups. Mapping of extinction risk within these spectra revealed that larger species with slower pace of life are universally threatened. Simulated potential extinctions revealed extensive internal reorganizations in the global functional spectra, which are particularly severe for mammals and amphibians. Considering the disproportionate importance of the largest species for ecological processes, our results emphasize the importance of actions to prevent the extinction of the megabiota.Competing Interest StatementThe authors have declared no competing interest.View Full Text

ecology↗

bioRxiv2018

Late greenhouse gas mitigation has heterogeneous effects on European caddisfly diversity patterns

Little remains known about how the timing of mitigation of current greenhouse gas emissions will influence freshwater biodiversity patterns. Using three general circulation models, we evaluate the response of 260 broad-ranging European caddisfly species to climate conditions in 2080 under two scenarios: business as usual (A2A) and mitigation (A1B). If implemented effectively, recent government commitments established under COP21, to mitigate current greenhouse gas emissions, would result in future climatic conditions similar to the mitigation scenario we explored. Under the Cgcm circulation model, which we found to be the most conservative model, suitable environmental conditions were predicted to shift 3{degrees} more to the east under the mitigation scenario compared to business as usual. The majority of broad-ranging European caddisfly species will benefit from mitigation, but 5 to 15% of species that we evaluated will be bigger losers under the mitigation scenario compared to business as usual. Under the mitigation scenario, caddisfly species that will retain less of their current range and experience lower predicted range expansion are those that currently have relatively limited distributions. Continental-scale assessments such as the ones that we present are needed to identify species at greatest risk of range loss under changing climatic conditions.

ecology↗