Molecular Ecology最新文献

Intensification of insecticide resistance in malaria vectors is undermining efforts to sustain control strategies. The evolutionary features underlying such exacerbation in major vector such as Anopheles funestus are only partially understood. PoolSeq whole genome analysis of Anopheles funestus from Mibellon (Cameroon), (alive and dead at 1×, 5× and 10× concentrations), failed to identify hits associated with resistance escalation. However, stronger signals emerge at the rp1 and CYP9 loci when comparing these phenotypes to the susceptible reference strain FANG, with genomic analysis using F₃ crosses implicating these regions in resistance evolution. Temporal genomic between 2014 and control unexposed 2021 populations confirmed substantial genomic changes largely confined to these two regions with evidence of selective sweeps linked to the presence of multiple novel replacement polymorphisms and signatures of complex genomic evolution emerging from major cytochrome P450 genes within the CYP9 and rp1 regions at increasing allelic frequencies in field individuals and alive genetic crosses, indicating that those variants are potentially driving resistance evolution. Combined genotyping of the rp1-based 4.3 kb SV and CYP9K1 (G454A) in alive and dead genetic crosses underscores their significant contribution to super-resistant phenotype in Anopheles funestus population in Mibellon. On the other hand, microbial composition changes, notably Elizabethkingia anophelis was associated with resistance evolution, suggesting their potential role in shaping the resistance phenotype while Serratia marcescens and Asaia bongorensis correlate with susceptibility. Genetic events and microbial symbionts associated with resistance evolution offer promising avenues for developing molecular markers to manage insecticide resistance.

Invasive pests threaten food security and devastate ecosystems. A universal problem in their management is that small populations can easily evade detection. This makes identifying new incursions challenging and complicates efforts to eradicate or contain established populations. If newly founded populations exhibited a strong Allee effect, small populations would tend towards extinction and most new incursions would go extinct without the need for detection or intervention. Of course, invasive species rarely exhibit strong Allee effects, but new genetic technologies make it conceivable to impose one. Here we consider how introduction of genetic load can cause a genetic Allee effect that reduces the establishment probability of small founder populations. Using numerical and individual-based modelling, we examine the fate of populations sampled from a larger invasive source population carrying deleterious recessive alleles. Our analysis reveals that the genetic load unmasked by founding can dramatically reduce the establishment probability of small populations across a wide range of parameter space. A sterile mutation effect is more effective than a lethal mutation effect, but X-linkage offers minimal benefit over autosomal inheritance. Although extinction of newly founded populations is a common outcome, it may be challenging to achieve in species with very high reproductive outputs. Distributing deleterious recessive alleles across a large number of loci at low frequencies was more effective than distributing them across fewer loci at higher frequencies. Our findings suggest that driving deleterious recessives into a source population may render it less prone to establish in new areas.

Intraspecific competition due to for example, density, has substantial influence on fitness dynamics and life histories, but the underlying physiological mechanisms are often complex and the molecular basis unclear. Further, designing laboratory experiments to measure physiological responses that reflect natural conditions is challenging. Here, we reared Atlantic salmon juveniles in semi-wild conditions in two densities to investigate the molecular mechanism of density-related changes in the hypothalamus, a key brain region regulating stress and energy homeostasis. We measured density-dependent changes in the expression of 12 genes involved in appetite and stress regulation and 16 genes involved in post-transcriptional regulation of gene expression via m⁶A RNA methylation. We also quantified genotype-environment interactions between density and two major life-history loci, vgll3 and six6. We found significant density-related differences in the expression of genes coding for corticotropin-releasing factors, appetite stimulators and inhibitors and m⁶A RNA methylation actors. Moreover, a paralogue of an appetite inhibitor showed a density-dependent pattern that was the opposite of what was expected. Six6 locus was also associated with changes in the expression of epitranscriptomic markers, including two writers and one eraser. Our results highlight that individuals' response to density in natural conditions is shaped by a complex interplay between stress, appetite and epitranscriptomic pathways in the hypothalamus. In addition, the functional divergence of paralogs indicates a potential role of genome duplication shaping such a response. We emphasise the value of integrating different physiological responses at the molecular level to better understand ecological processes affected by environmental change.

Land use change and agricultural expansion threaten biodiversity yet the effects on soil life remain poorly understood, especially for microbes. Arbuscular mycorrhizal (AM) fungi are microbes that form associations with most plant species and are essential for plant nutrient uptake. The diversity of these fungi is also sensitive to both land use change and regional climatic conditions. We therefore asked whether variation in AM fungal diversity is driven by land use change, and whether these effects are further influenced by interactions with temperature and precipitation gradients. To test this, we quantified AM fungal biodiversity in cultivated and adjacent uncultivated soils across a 1700 m elevational gradient (temperature: 7.7°C-16.5°C and precipitation: 1000-3500 mm). We found that conversion of uncultivated soils to agriculture reduced AM fungal richness by 80%, on average. Richness in uncultivated soils increased with the temperature gradient, while richness in farms declined. A similar but inverted trend was found for precipitation, where richness in uncultivated sites declined as precipitation increased. Uncultivated soils contained approximately three-fold more unique AM fungal species compared to cultivated soils. Our findings demonstrate that interactions between climate and land use strongly influence AM fungal biodiversity patterns in tropical mountain ecosystems. Incorporating both factors into conservation and sustainable agriculture strategies will be critical to preserving belowground biodiversity under global change.

Seminal fluid proteins are important modulators of male fertility and reproductive success, yet little is known about how their abundance responds to early-life developmental stress. Japanese quail Coturnix japonica) males produce a unique seminal foam that enhances fertilisation success. We characterised the proteome of the seminal foam for the first time and assessed how its composition is influenced by prenatal and postnatal developmental stress. Proteomic identification using liquid chromatography-tandem mass spectrometry and subsequent gene ontology (GO) analysis of chicken (Gallus gallus domesticus) orthologs suggested roles for the foam proteome in sperm maturation and DNA protection, semen liquefaction, sperm plasma membrane homeostasis and energy production for sperm motility. Males that experienced prenatal stress exhibited increased abundance of proteins involved in lipid metabolic processes, inflammation and oxidative stress, including proteolytic enzymes, interleukin receptors and avidin-like proteins. Similarly, males that exhibited postnatal stress exhibited increased abundance of proteins involved in chromatin organisation, carbon metabolism and oxidative stress. Nine proteins involved in metabolic processes and antioxidant processes were consistently more abundant across developmentally stressed males from both experiments, suggesting convergent responses to early-life stress. These results demonstrate that early development environments can alter the seminal foam proteome of adult males, with potential implications for ejaculate quality and fertilisation ability.

In boreal and tundra ecosystems, mosses are abundant and ecologically important members of the vegetation due to their ability to insulate permafrost and maintain soil moisture. Mosses also harbour diverse bacterial and fungal symbionts that can provide nutrients and protection against environmental stressors. Sphagnum mosses are particularly important due to their significant role in carbon sequestration, which has been attributed in part to the production of antimicrobial metabolites that slow decomposition. Although Sphagnum leachate has been shown to inhibit bacteria, how Sphagnum chemical traits impact fungal communities remains understudied. Here, we used culture-free and culture-based methods to examine the relationship between moss fungal communities and metabolomes in living and senescing tissues of Sphagnum and two co-occurring moss genera across four Alaskan boreal/tundra sites. Although their richness was similar among moss genera, fungal and metabolite composition differed significantly among moss genera, regardless of tissue age. Importantly, mosses with more similar metabolome composition harboured more similar fungal communities, particularly in living tissues. Numerous OTU-metabolite correlations suggest direct interactions whereby fungi may consume, degrade, and/or be inhibited by metabolites; however, in vitro growth of moss-associated fungi showed inhibition in only 25% of replicates with two phenolic metabolites. Overall, our data suggest that metabolites may be a key factor structuring fungal communities in Sphagnum and other mosses, although not solely via inhibitory effects. Given the significance of mosses to ecosystem function and carbon sequestration in northern regions, it is critical to better understand factors that shape fungal communities potentially involved in stress adaptation and decomposition.

In recent decades, wildfire regimes have changed significantly, with increases in frequency, severity and area affected, leading to major habitat alterations that may impact species ecology. While fire's role in plant ecology is well studied, its effects on animal biotic interactions remain poorly understood. In northern Portugal, where wildfires are common, the native rock-dwelling lizard Podarcis lusitanicus may thrive postfire due to its preference for open rocky outcrops, which expand after fires. This suggests not only resilience but also a capacity for persistence in postfire disturbances driven by habitat preferences. However, changes in prey availability after fire induce dietary shifts in this insectivorous lizard, potentially affecting trophic interactions and, consequently, gut microbiota communities. Gut microbiota influence host fitness through effects on nutrition, immunity and behaviour; on the other hand, gut microbiota are affected by variations in diet and environment. This study assessed how fire history affects P. lusitanicus gut microbiota. Sampling occurred across 12 sites in northern Portugal, representing three fire histories: long-unburned, burned in 2016 and burned in 2022. Cloacal swabs were analysed by metabarcoding the V4 region of the 16S rRNA gene. Results showed that gut bacterial composition varied with fire history, as well as with sex, body size and diet. Females had higher microbial richness despite similar diet richness between sexes. While microbiome composition shifted, predicted microbiome function remained relatively stable, indicating both resilience and ecological flexibility in fire-prone environments. These findings enhance understanding of how lizard microbiomes respond to environmental disturbances and may help predict host and microbiota tolerance under changing fire regimes.