Biology subjects

Rawstern, A. H.

Publications and source records attributed to Rawstern, A. H..

4 recordsLinked to original sources

bioRxiv2026

Hidden drivers of restoration: Persistent divergence in soil microbiome functional capacity post-habitat reconstruction

Ecosystems today are facing unprecedented environmental stress, leading to large-scale losses of habitat and ecosystem services. To address this, reconstructive efforts aim to restore habitat features and their natural complexity, biodiversity, and function. However, many reconstructive efforts fail to consider microbial communities, even though they play key roles in decomposition, nutrient cycling, and plant and animal health. Here, we use shotgun metagenomic sequencing to compare the structure and functional capacity of soil microbial communities from natural Everglades tree islands and islands constructed within a landscape-scale experimental Everglades restoration effort, followed by a manipulative greenhouse experiment to link tree sapling traits with microbiome functional genetic divergence. We found that constructed and natural island microbiomes exhibited strong, robust, and persistent divergence in both taxonomic and functional composition, with natural island microbial communities having greater functional genetic diversity and redundancy. Furthermore, we identified enrichment in functional pathways in constructed island microbiomes such as those involved in pollutant degradation that may reflect continued disturbance leading to shifts in microbiome functional profiles. Despite their capacity for functions such as nitrogen cycling we found to be important for supporting sapling growth, constructed island microbiomes displayed reduced functional genetic diversity and redundancy and were enriched in pathways associated with environmental disturbance, suggesting a potentially diminished capacity for long-term resilience. Overall, our assessment of soil microbial communities in reconstructed and natural habitats emphasizes how reconstructive restoration can impact microbial functional repertoires and highlights the importance of these hidden players in management and restoration of ecosystem health.

ecology↗

bioRxiv2026

Land-use intensity overrides grazing and precipitation effects on soil microbial communities in a subtropical agroecosystem

Global change drivers are reshaping agroecosystems and their sustained functions worldwide. While soil microorganisms underpin the resilience of these systems, the individual and interactive effects of multiple anthropogenic stressors on microbial community structure and function using large-scale field experiments remain poorly understood. Here, we utilize a full-factorial field experiment in a subtropical agroecosystem to investigate how land-use intensity, cattle grazing intensity, and altered precipitation regimes interact to shape soil microbiomes. Combining microbiome sequencing with network analyses and functional bioinformatics, we evaluated effects of these drivers on prokaryotic and fungal diversity, composition, predicted functional profiles, and community structure. Land-use intensity emerged as the primary driver of microbial responses, explaining 25% and 13% of the total variation in community composition for prokaryotes and fungi, respectively. Compared to intensively managed pastures, semi-natural pastures had significantly different community composition for prokaryotes and fungi and exhibited 22% higher fungal diversity. Semi-natural pastures were enriched with decomposer-associated taxa and metabolic pathways related to energy and lipid metabolism indicating enhanced microbial activity. Surprisingly, intensively managed pastures showed higher network modularity but lower network richness, suggesting a trade-off between community compartmentalization and complexity under intensive land management. Grazing and precipitation manipulations induced core microbiome changes within land-use intensities but had no impact on overall community structure and no significant interactions with land-use. Together, these findings suggest that long-term land-use legacies exert a persistent influence on soil microbial community structure, function, and organization, shaping the context within which other global change drivers operate in subtropical agroecosystems.

ecology↗

bioRxiv2025

Non-additive interactions between multiple mutualists and host plant genotype simultaneously promote increased plant growth and pathogen defense

Understanding the impact of microbial interactions on plants is critical for maintaining healthy native ecosystems and sustainable agricultural practices. Despite the reality that genetically distinct plants host multiple microbes-of-large effect in the field, it remains unclear the extent to which host genotypes modulate non-additive microbial interactions and how these interactions differ between benign/pathogenic environments. Our study fills this gap by performing a large-scale manipulative microbiome experiment across 7 genotypes of the model legume Medicago truncatula. We combine plant performance metrics, survival analyses, predictive modeling, RNA extractions, and targeted gene expression to assess how host genotype and microbes non-additively interact to shape plant growth and disease ecology. Our results reveal three important findings: (1) host genotypes with high tolerance to pathogens benefit more from multiple mutualist interactions than susceptible genotypes, (2) mutualists confer the same non-additive plant performance benefits in both benign and pathogenic environments, and (3) the quality of the symbiotic relationship with mutualists is a strong predictor of host survival against pathogenic disease. By applying these findings towards developing crops that promote synergistic microbial interactions, yields and pathogen defense could be simultaneously increased while reducing the need for toxic fertilizers and pesticides.

plant biology↗

bioRxiv2023

Hub taxa are keystone microbes during early succession

Microorganisms underpin numerous ecosystem processes and support biodiversity globally, yet we understand surprisingly little about what structures environmental microbiomes themselves. Combining culturing, sequencing, and microbial networks, we identified central (highly-connected, hub taxa), intermediate (moderately-connected), and peripheral (weakly/un-connected) microbes and experimentally evaluated their effects on soil microbiome assembly during early succession. Our results demonstrate central early colonizers significantly (1) enhanced biodiversity, (2) increased recruitment of additional influential, hub taxa, and (3) shaped microbiome assembly trajectories. This work elucidates fundamental principles of network theory in microbial ecology and demonstrates for the first time in nature that central, hub microbes are keystones.

microbiology↗