Biology subjects

Dopson, M.

Publications and source records attributed to Dopson, M..

3 recordsLinked to original sources

bioRxiv2026

The impacts of grazing pressure by large herbivores on short-tailed field vole (Microtus agrestis) population cycles: results from a long-term upland experiment

Understanding how large herbivores influence cyclic small-mammal populations is essential for predicting community dynamics in grazed ecosystems. Using a 23-year upland grazing experiment in Scotland, United Kingdom, we test how varying livestock grazing pressures affect population cycles of the short-tailed field vole Microtus agrestis, a keystone herbivore and prey species of birds of conservation concern. We combined long-term vole sign indices (VSI), vegetation surveys, climate data and used wavelet analyses and mixed-effects models to quantify changes in VSI (a proxy for abundance), cycle amplitude and periodicity across four grazing treatments and three spatial blocks. Vole abundance and cycle amplitude declined with increasing grazing pressure, yet the frequency of vole population oscillations remained strikingly consistent across all treatments, with a dominant ~3.5-year cycle persisting throughout most of the study. Ungrazed plots supported the highest mean VSI and the largest amplitude oscillations. We found a pronounced, spatially-restricted cycle collapse occurred between 2009-2016 in one experimental block. This breakdown coincided with unusually cold winters and lower vegetation density, suggesting that local microclimate and habitat structure interact to destabilise vole cycles. Vegetation density (but not height) predicted VSI in the more intensively grazed treatments, indicating that grazing-driven changes in habitat structure indirectly mediate vole dynamics. Our findings demonstrate that large herbivores can substantially modify vole population dynamics through both direct and indirect pathways, altering cycle amplitude, habitat suitability and resilience to climatic perturbations. These results highlight the need to consider interactions between grazing, vegetation structure and climate variability when predicting small-mammal population dynamics and their cascading ecological effects.

ecology↗

bioRxiv2024

Cross-feeding options define eco-evolutionary dynamics of deep oligotrophic groundwater microbiome

Deep groundwaters populated by diverse and active microbes are among the most energy and nutrient-limited ecosystems. Characteristics of this ecosystem including nutrient and dispersal limitations, low cell densities, and episodic growth strategy interactively underpin the so far elusive eco-evolutionary dynamics of its microbiome. Here we applied a modular metabolic analyses on genome-resolved reconstructed community of disconnected deep groundwaters in the Fennoscandian Shield. In the community of deeper groundwaters despite their highly oligotrophic nature, lineages with larger genomes maintained larger populations which we hypothesize to be connected with their limited cross-feeding options. Thus providing an extension on the streamlining theory emphasizing the importance of ecological interactions in genome evolution which is further supported by the observed decrease in abundance of lineages with known metabolic dependencies, such as Patescibacteria and DPANN, with depth. The modular metabolic analyses showed that remarkably common niches based on same cross-feeding interactions are also available in different groundwaters, in addition to common niches for primary production. While these shared niches are critical for community assembly in this ecosystem, in different boreholes different lineages populated them. Our results provided new insights into the role of metabolic cross-feeding in genome evolution and community assembly of deep groundwater microbiome.

microbiology↗

bioRxiv2020

Energy efficiency and biological interactions define the core microbiome of deep oligotrophic groundwater

Extremely oligotrophic deep groundwaters host organisms attuned to the low-end of the bioenergetics spectrum. While all domains of life along with viruses are active in this habitat, the evolutionary and ecological constraints on colonization and niche shifts and their consequences for the microbiome convergence are unknown. Here we provide a comparative genome-resolved analysis of the prokaryotic community in disconnected fracture fluids of the Fennoscandian Shield. The data show that the oligotrophic deep groundwaters flowing in similar lithologies offer fixed niches that are occupied by a common deep groundwater core microbiome. Based on this high resolution "multi-omics" enabled understanding of the underlying mechanisms via functional expression analysis, we conclude that deep groundwater ecosystems foster highly diverse, yet cooperative microbial communities adapted to this setting. The fitness of primary energy producers is increased by ecological traits such as aggregate or biofilm formation. This also facilitates reciprocal promiscuous partnerships with diverse and prevalent epi-bionts, alleviating the "tragedy of common goods". Hence, instead of a lifestyle where microbes predominantly invest in functions related to maintenance and survival, an episodic and cooperative lifestyle ensures the subsistence of the deep groundwater microbiome. We suggest the name "halt and catch fire" for this way of life.

microbiology↗