Biology subjects

Maurice, S.

Publications and source records attributed to Maurice, S..

8 recordsLinked to original sources

bioRxiv2026

Arthropod succession from deadwood to soil: increasing diversity and transitions between major forest substrates

Deadwood is a common ephemeral resource in boreal forests, but arthropod succession across the full decay gradient and transition into soil remains poorly understood. We analyzed the successional trajectory of arthropods in deadwood to soil. Further, we investigated whether the succession pattern differed in previously clear-cut and near-natural forests in southeastern Norway. This was done by DNA metabarcoding analyses of arthropod communities in collected deadwood and soil samples. We detected 741 arthropod OTUs, with 565 OTUs in deadwood and 291 in organic soil layers, of which 115 were found in both deadwood and organic soil layers. Arthropod richness increased with deadwood decay stage and organic soil layers supported higher richness than all deadwood decay stages. Community composition of arthropods changed significantly along the decay gradient, with late-decay stages sharing more OTUs with organic soil layers than with earlier decay stages. This suggests a gradual transition between communities in highly decayed deadwood and organic soil layers. Forest type (previously clear-cut vs. near-natural forest) had limited effects on overall richness and community composition, although previously clear-cut and near-natural forests supported partially distinct species pools and differed in co-occurrence patterns in late decay and organic soil layers. Our results show that arthropod communities are strongly structured along the decay gradient from freshly dead wood to organic soil layers. This highlights the importance of retaining deadwood across different decay stages for maintaining arthropod diversity and community convergence between deadwood and soil in boreal forests.

ecology↗

bioRxiv2026

Genotyping the self-incompatibility locus of wild and cultivated Brassica using NGS technologies: application to the evaluation of mate limitation in the endangered species Brassica insularis

O_LISelf-incompatibility can limit the availability of compatible mates in small and isolated populations, eventually reducing average seed set to the point that the long-term persistence of the populations can be impaired. This phenomenon, named the S-Allee effect, is caused by the loss of alleles (S-alleles) at the self-incompatibility locus (S-locus) due to the intense genetic drift experienced by small populations. Quantifying the diversity of S-alleles is therefore of direct interest for biological conservation, but efficient genotyping methods have been lacking so far because of technical challenges associated with the typically extreme levels of polymorphism and complex genomic structure of the S-locus. C_LIO_LIWe used two alternative approaches to genotype the S-locus using NGS sequencing technologies in four natural populations of the endangered Brassica insularis in Corsica. First, we used an NGS amplicon-sequencing approach using generalist primers for each of the two classes of Brassica S-alleles. Second, we obtained whole genome shotgun short-read resequencing data and analyzed them with a recently developed bioinformatic pipeline dedicated to hypervariable loci, which we successfully validated on a public dataset comprising 119 cultivated accessions of B. oleracea. C_LIO_LIBy combining the two approaches in natural populations of B. insularis we identified 31 distinct S-alleles and obtained fully resolved S-locus genotypes for 319 out of 326 sampled individuals. The number of S-alleles varied from four in the smallest population to 18 in the largest one. As a result, the smallest population exhibited very low proportions of compatible individuals, potentially threatening its persistence. We conclude that introducing individuals carrying S-alleles currently absent from the population could help rescue fertility. C_LI

evolutionary biology↗

bioRxiv2026

Long-term shift in community composition of deadwood fungi after clear-cutting

O_LIRising anthropogenic pressures in the 20th century have caused extensive habitat loss and fragmentation, threatening biodiversity across ecosystems worldwide. In the boreal forest of Fennoscandia, clear-cut forestry has been a major driver of these changes, resulting in a fragmented landscape of even-aged forest stands. Several studies in recent years have investigated the effect of habitat fragmentation and loss on fungal communities associated with deadwood, but these have mainly focused on visible sporocarps and mushrooms. The effects of forestry on the whole fungal community within deadwood have not been explored as extensively, and especially not in the context of long-term effects. C_LIO_LIWe investigated the effects of clear-cutting on deadwood-inhabiting fungi in boreal Picea abies forests in Norway using ITS2 metabarcoding of sawdust samples collected from 459 logs distributed across 24 paired near-natural and previously clear-cut plots harvested 50 to 90 years ago. C_LIO_LIWhile the overall fungal richness associated with deadwood was similar between the two management types, community composition differed markedly. Plot-scale fungal diversity was linked to deadwood heterogeneity, and composition of the common species was additionally affected by the living tree structure. Nearly all red-listed species were exclusively found in the near-natural forest plots. These findings demonstrate that clear-cut forestry shifts fungal community structure rather than reducing the total number of species and that rare and common species are structured by different environmental drivers but respond in similar ways to large scale disturbance. C_LIO_LISynthesis: Our results highlight the importance of maintaining structural complexity of deadwood in boreal forests for fungal conservation. We found a consistent relationship between deadwood volumes and heterogeneity, and community diversity and species richness. This relationship was consistent even for previously clear-cut forests, showing that retaining structural heterogeneity in managed ecosystems has a positive impact on species diversity. C_LI

ecology↗

bioRxiv2025

Uncovering Functional Sequence Gaps in Human Reference Genomes using African Pan Genome Contig Sequences

Human reference genomes underpin biomedical discovery but remain incomplete and biased toward European populations, constraining interpretation of genetic variation in underrepresented populations. Here we characterize African Pan Genome (APG) contigs totaling 296.5 Mb to define the sequence and functional landscape of genomic regions absent from current references. Most contigs align to the telomere-to-telomere (T2T-CHM13) genome and across 47 haplotype-resolved Human Pangenome Reference Consortium (HPRC) assemblies, with T2T-CHM13 placements enriched in centromeric and satellite repeats and overlapping 373 genes, including disease-associated loci. Mapping across HPRC assemblies revealed ancestry-associated contig enrichment, particularly in African genomes. Notably, 742 contigs remained unmapped under both stringent and relaxed criteria. These sequences are largely nonrepetitive and exhibit strong functional potential, including predicted protein-coding genes, CpG islands and transcriptional activity. Together, these results demonstrate that functionally relevant, ancestry-enriched genomic sequences remain absent from current references, with important implications for disease variant interpretation and precision medicine.

genomics↗

bioRxiv2024

Yeasts prefer daycares and molds prefer private homes

Indoor fungi can cause negative health effects due to the production of toxins or volatiles that trigger the immune system of the occupants. To what degree indoor fungi (mycobiomes) differ between buildings with different usage is poorly known. Here, we compare the indoor mycobiomes in 123 childrens daycare centers and 214 private homes throughout Norway, as revealed by metabarcoding of DNA extracted from dust samples collected by community scientists. Although the fungal richness per se was similar in dust samples from daycares and homes, the fungal community composition differed. Yeast fungi, distributed mainly across the orders Saccharomycetales, Filobasidiales and Tremellales, were proportionally more abundant in the daycares, while filamentous fungi, including spore-producing molds such as Aspergillus, Penicillum and Cladosporium, were relatively more abundant in homes. Number of occupants, which is considerably higher in daycares, correlated significantly with the fungal community shift. We hypothesize that the density of occupants and their age distribution drive the systematic difference of yeasts and filamentous fungi in the two building types. ImportanceWorldwide, people spend most of their time indoors; in their homes, workplaces, schools and daycares. The indoor environment can thus largely influence our health. In this study, we revealed that number of occupants and possibly their age distribution are important explanatory variables for the fungal communities of the indoor environments in homes and daycares. Knowledge of these communities are important for further studies on how fungal diversity affect our health.

microbiology↗

bioRxiv2023

Reticulate evolution and rapid development of reproductive barriers upon secondary contact pose challenges for species delineation in a forest fungus

Reproductive barriers within morphospecies of the mushroom-forming fungi tend to be stronger between sympatric lineages, leading to speculation on whether they are being reinforced by selection against hybrids. In this study we use population genomic analyses together with in vitro crosses of a global sample of the wood decay fungus Trichaptum abietinum to investigate reproductive barriers within this morphotaxon and the processes that have shaped them. Our phylogeographic analyses show that the morphospecies is delimited into six major lineages, one in Asia, two in Europe, and three in North America. The two lineages present in Europe are interfertile and admixed, whereas our crosses show that the North American lineages are reproductively isolated. In Asia a more complex pattern appears, with partial intersterility between multiple sub-lineages that likely originated independently and more recently than the reproductive barriers in North America. We found pre-mating barriers in T. abietinum to be moderately correlated with genomic divergence, whereas fitness of the mated hybrids showed a strong positive correlation with increasing genomic divergence. Genome wide association analyses identified candidate genes with programmed cell death annotations, which are known to be involved in intersterility in distantly related fungi. Our demographic modelling and phylogenetic network analyses suggest that reproductive barriers in Trichaptum abietinum could have been reinforced upon secondary contact between lineages that diverged in allopatry during the Pleistocene glacial cycles. Our combination of experimental and genomic approaches demonstrate how T. abietinum is a tractable system for studying speciation mechanims.

evolutionary biology↗

bioRxiv2021

The indoor mycobiome of daycare centers is affected by occupancy and climate

Many children spend considerable time in daycare centers and may here be influenced by indoor microorganisms, including fungi. In this study, we investigate the indoor mycobiome of 125 daycare centers distributed along strong environmental gradients throughout Norway. Dust samples were collected from doorframes outside and inside buildings using a citizen science sampling approach. Fungal communities in the dust samples were analyzed using DNA metabarcoding of the ITS2 region. We observed a marked difference between the outdoor and indoor mycobiomes. The indoor mycobiome included considerably more yeasts and molds compared to the outdoor samples, with Saccharomyces, Mucor, Malassezia and Penicillium among the most dominant fungal genera. Changes in the indoor fungal richness and composition correlated to numerous variables related to both outdoor and indoor conditions; there was a clear geographic structure in the indoor mycobiome composition that mirrored the outdoor climate, ranging from humid areas in western Norway to drier and colder areas in eastern Norway. Moreover, the number of children in the daycare centers, as well as various building features, influenced the indoor mycobiome composition. We conclude that the indoor mycobiome in Norwegian daycare centers is structured by multiple factors and is dominated by yeasts and molds. This study exemplifies how citizen science sampling enables DNA-based analyses of a high number of samples covering wide geographic areas. ImportanceWith an alarming increase in chronic diseases like childhood asthma and allergies, there is an increased focus on the exposure of young children to indoor biological and chemical air pollutants. Our study of 125 daycares throughout Norway demonstrates that the indoor mycobiome not only reflects co-occurring outdoor fungi but includes a high abundance of yeast and mold fungi with an affinity for indoor environments. A multitude of factors influence the indoor mycobiome in daycares, including building type, inhabitants, as well as the outdoor environment. Many of the detected yeasts and molds are likely associated with the human body, where some have been coupled to allergies and respiratory problems. Our results call for further studies investigating the potential impact of the identified daycare-associated mycobiomes on children health.

microbiology↗

bioRxiv2021

DNA metabarcoding reveals host-specific communities of arthropods residing in fungal fruit bodies

Biological communities within living organisms are structured by their hosts traits. How host traits affect biodiversity and community composition is poorly explored for some associations, such as arthropods within fungal fruit bodies. Using DNA metabarcoding, we revealed the arthropod communities in living fruit bodies of eleven wood-decay fungi from boreal forests and investigated how they were affected by different fungal traits. Arthropod diversity was higher in fruit bodies with a larger surface area-to-volume ratio, suggesting that colonisation is crucial to maintain arthropod populations. Diversity was not higher in long-lived fruit bodies, most likely because these fungi invest in physical or chemical defences against arthropods. Arthropod community composition was structured by all measured host traits, namely fruit body size, thickness, surface area, morphology and toughness. Notably, we identified a community gradient where soft and short-lived fruit bodies harboured more true flies, while tougher and long-lived fruit bodies had more oribatid mites and beetles, which might reflect different development times of the arthropods. Ultimately, close to 75% of the arthropods were specific to one or two fungal hosts. Besides revealing surprisingly diverse and host-specific arthropod communities within fungal fruit bodies, our study provided insight on how host traits structure communities.

ecology↗