Biology subjects

Weber, S. E.

Publications and source records attributed to Weber, S. E..

4 recordsLinked to original sources

bioRxiv2026

Loss of a belowground mutualist disrupts a fundamental biodiversity-disease relationship

Diverse ecological communities can reduce pathogen transmission; a phenomenon known as the dilution effect of biodiversity. This effect, in turn, depends on variation in host species' ability to spread disease (i.e., host competence) and which host species persist under biodiversity loss. Mutualistic symbionts can influence host competence and are sensitive to variation in host biodiversity; yet whether mutualists can modify dilution effects is unknown, partially because quantifying host competence during epidemics remains challenging. We experimentally tested whether mutualists could modify dilution effects by establishing gradients of host species richness, community competence, and access to the below-ground arbuscular mycorrhizal fungus (AMF), Rhizoglomus irregulare. Plant hosts were then exposed to the fungal root pathogen, Rhizoctonia solani, and disease spread was monitored over the course of an epidemic. Overall, host richness did not affect epidemic outcomes. Instead, AMF inoculation increased disease risk via species-specific increases in host competence. Moreover, communities containing highly competent host species experienced more disease, but only in the presence of mutualistic AMF. These results underscore the importance of plant community composition in mycorrhiza-mediated disease dynamics and suggest that predicting disease in our changing world might require a deeper understanding of host-symbiont and pathogen-symbiont interactions under global change.

ecology↗

bioRxiv2026

Immunoregulatory gene GIMAP6 suppresses lethal atherosclerotic vasculopathy and ischemic heart failure

Controlling hyperlipidemia has reduced but not eliminated atherosclerotic cardiovascular disease as a predominant cause of human mortality. Here, we report that loss of the immunoregulatory gene GTPase of immunity-associated protein 6 (GIMAP6), causes an inflammatory vasculopathy and accelerated atherosclerosis in the absence of hyperlipidemia. These pathologic changes in turn result in progressive cardiac ischemia, myocardial infarction, and heart failure, culminating in early death. In humans, rare deleterious GIMAP6 variants are associated with premature severe cardiovascular disease. These findings reveal GIMAP6 to play an important protective role against atherosclerotic cardiovascular disease whose identification offers opportunities for improved risk management and a target for new therapies.

immunology↗

bioRxiv2025

Warming and elevated CO2 cause greater and deeper root growth by shrubs in a boreal bog

1Boreal bogs sequester large stores of terrestrial carbon in waterlogged peat occupied by extensive networks of vascular plant roots. Historically, cold temperatures and shallow water tables in bogs have favored the growth of Sphagnum over vascular plants. Seasonally variable water tables in bogs constrain woody shrub and tree root production to shallow, oxic acrotelm peat horizons while herbs with aerenchymous root tissue can grow below the water table. Warming and elevated CO2 are altering ecosystem functioning in nutrient-limited, rain-fed (ombrotrophic) bogs, via direct impacts on physiology and indirectly via altering water table levels. The environmental changes are shifting interactions between vascular plant fine-roots and the surrounding peat horizons and increasingly favoring vascular plant growth relative to Sphagnum sp. Altered functioning of fine-roots may dramatically affect the role of plants in these ecosystems because of the importance of these organs for plant resource acquisition. We examined how fine-roots across vascular PFTs differentially respond to warming & elevated CO2 manipulations and the consequent water table depression in a forested, boreal bog. We used minirhizotrons (cameras inserted belowground) to measure fine-root production, depth distribution, and standing crop from 2015-2021 for each PFT. We found that daily rates of fine-root production accelerated more for shrubs than for trees or herbs. Shrubs and trees grew their roots more deeply with depressed water table levels and shrub fine-roots became narrower. On an annual basis, fine-root production increased with warming, though these rates varied among PFTs and exhibited interactions with elevated CO2. Standing crop of fine-roots increased with warming temperatures, most strongly for shrubs under elevated CO2, because of these productivity responses. From these results, we expect boreal bogs will become increasingly dominated by shrubs under future warmer temperatures, higher atmospheric CO2 concentrations, and lower water table levels.

ecology↗

bioRxiv2018

Fungal community assembly in soils and roots under plant invasion and nitrogen deposition

Abstract Fungal community composition in the Anthropocene is driven by rapid changes in environmental conditions caused by human activities. This study examines the relative importance of two global change drivers - atmospheric nitrogen (N) deposition and annual grass invasion - on structuring fungal communities in a California chaparral ecosystem, with emphasis on arbuscular mycorrhizal fungi. We used molecular markers, functional groupings, generalized linear statistics and joint distribution modeling, to examine how environmental variables structure taxonomic and functional composition of fungal communities. Invasion of a chaparral ecosystem decreased richness and relative abundance of non-AMF symbionts and rhizophilic AMF (e.g. Glomeraceae) as well as the proportion of edaphophilic AMF (e.g. Gigasporaceae). We found increased richness and the proportion of rhizophilic and edaphophilic AMF with increasing soil NO3. Our findings suggest that invasive persistence may decrease the presence of multiple soil symbionts that native species depend on for pathogen protection and increased access to soil resources.

ecology↗