Biology subjects

Shurin, J. B.

Publications and source records attributed to Shurin, J. B..

4 recordsLinked to original sources

bioRxiv2026

Consistent, scale-dependent differences in the biogeography of host-associated and free-living microbiomes across systems

Microbial communities are critical to the functioning of ecosystems and shape the ecology and evolution of host organisms. However, we have a limited understanding of how host-associated and free-living microbes differ in their structure and biogeography. Here, we test whether host-associated (fish gut) and free-living (lake bacterioplankton) microbes exhibit different metacommunity structure, spatial turnover, and consistency with neutral expectations using two independent lake systems. We characterized microbial communities in lake water (Vancouver Island and Sierra Nevada) and guts in two fish species (stickleback and brook trout) using 16S amplicon sequencing. We compared alpha and beta diversity within lakes, quantified spatial turnover (distance-decay), and tested for departure from neutral abundance-occurrence expectations between bacterioplankton and fish gut microbiomes. Fish microbiomes had lower alpha diversity compared to bacterioplankton, but higher beta diversity within lakes. Bacterioplankton were more similar across lakes yet showed stronger patterns of spatial turnover with distance than fish gut microbiomes. A neutral model explained a substantial proportion of abundance-occurrence relationships in bacterioplankton communities but performed poorly for fish-associated microbes. Our study indicates that host-associated and free-living microbes have disparate patterns of metacommunity structure and spatial turnover consistent with differences in the strength of neutral ecological processes. Fish microbiomes were less diverse at the local scale but more variable across space and time than bacterioplankton communities, suggestive of potentially strong local selection and/or reduced microbial exchange among hosts compared to environmental communities. Importantly, we observed highly consistent patterns across both lake systems despite differences in host species, sampling design, and region, demonstrating that differences in the distribution of host and environmental microbes are potentially widespread. This study demonstrates how host association fundamentally alters the diversity and spatial distribution of microbes, emphasizing the need to incorporate hosts into broader frameworks of microbial biogeography.

ecology↗

bioRxiv2025

Microplastic pollution induces algae blooms in experimental ponds but bioplastics are less harmful

An ever-growing sea of plastic waste permeates even the most remote ecosystems; however, its ecological impact is unclear. Less persistent bioplastic alternatives are available but also have unknown environmental effects. We conducted a three-month experiment exposing plankton in experimental ponds to 10 concentrations of three different thermoplastic polyurethane microplastics, including two biodegradable bioplastics. Algal blooms with dense chlorophyll occurred consistently at high concentrations of the petroleum-derived thermoplastic polyurethane, but only occasionally with the two bioplastics. Herbivorous zooplankton density was strongly reduced by typical thermoplastic polyurethane and only weakly by bioplastics, therefore the effect on algae is at least partly due to reductions in top-down grazing pressure. Microbial communities exhibited compositional shifts in response to all three plastic types, with petroleum-derived plastic associated with the most pronounced differences across both prokaryotic and eukaryotic domains. Our results show that plastic pollution may contribute to the growing global problems of eutrophication, coastal hypoxia and harmful algae blooms, and that biodegradable plastics may have smaller environmental footprints.

ecology↗

bioRxiv2025

The impact of microplastic contamination in cow manure on reproductive behavior and larval survival in the dung beetle Onthophagus taurus

Microplastics are an emerging environmental hazard on a global scale. Their detection in agricultural environments is of particular concern not only for food contamination, but also because microplastics negatively impact detritivores and their ecosystem functioning. Dung beetles in particular provide vital ecosystem services in agricultural environments and are often vulnerable to anthropogenic hazards, but whether they are affected by microplastics remains unclear. Here, we test whether artificial contamination of cow dung with thermoplastic polyurethane (TPU) has the potential to affect the juvenile development and maternal behavior of the bull-headed dung beetle Onthophagus taurus. Dung beetles exhibited high mortality when exposed to elevated concentrations of TPU. In addition, females were equally likely to provision offspring with TPU-spiked (and lethal) cow dung as with control dung, suggesting that females cannot differentiate between highly toxic microplastic-contaminated and uncontaminated cow dung. Our findings highlight potentially severe consequences for dung beetles if microplastics persist and accumulate, although the levels of exposure in the field are unknown. Although the direct environmental hazards and the mechanisms mediating the negative impacts of TPU microplastics remain to be assessed, this study suggests that microplastics may negatively impact dung beetles and their ecosystem services. Future work assessing exposure levels in the field as well as dung beetles potential to evolve resistance against microplastic pollution will be necessary to assess the long-term impact of microplastic presence on dung beetle ecosystem functioning.

ecology↗

bioRxiv2022

Phenotypic and transcriptional response of Daphnia pulicaria to the combined effects of temperature and predation

Daphnia, an ecologically important zooplankton species in lakes, shows both genetic adaptation and phenotypic plasticity in response to temperature and fish predation, but little is known about the molecular basis of these responses and their potential interactions. We performed a factorial experiment exposing laboratory-propagated Daphnia pulicaria clones from two lakes in the Sierra Nevada mountains of California to normal or high temperature (15{degrees}C or 25{degrees}C) in the presence or absence of fish kairomones, then measured changes in life history and gene expression. Exposure to kairomones increased upper thermal tolerance limits for physiological activity in both clones. Cloned individuals matured at a younger age in response to higher temperature and kairomones, while size at maturity, fecundity and population intrinsic growth were only affected by temperature. At the molecular level, both clones expressed more genes differently in response to temperature than predation, but specific genes involved in metabolic, cellular, and genetic processes responded differently between the two clones. Although gene expression differed more between clones from different lakes than experimental treatments, similar phenotypic responses to predation risk and warming arose from these clone-specific patterns. Our results suggest that phenotypic plasticity responses to temperature and kairomones interact synergistically, with exposure to fish predators increasing the tolerance of Daphnia pulicaria to stressful temperatures, and that similar phenotypic responses to temperature and predator cues can be produced by divergent patterns of gene regulation.

ecology↗