Biology subjects

Zahn, G. L.

Publications and source records attributed to Zahn, G. L..

5 recordsLinked to original sources

bioRxiv2024

Aquatic plant mycobiomes change with watershed urbanization

Urban expansion, projected to triple globally from 2000 to 2030, significantly impacts biodiversity and ecosystem processes, including those of microbial communities. While extensive research has examined urbanization effects on macro-organisms, the impacts on microbial communities, particularly those associated with aquatic plants, remain underexplored. This study investigates the fungal endophyte communities in the pollution-tolerant aquatic plant Ranunculus aquatilis along an urbanization gradient in the Provo River, Utah, USA, a rapidly urbanizing region. We collected plant and adjacent water samples from ten locations along the river, spanning from rural to urbanized areas, and conducted DNA amplicon sequencing to characterize fungal community composition. Our results show a significant decline in fungal alpha diversity downstream, correlated with increased urbanization metrics such as impervious surface area and developed land cover. Specifically, fungal ASV richness and Shannon diversity decreased as urbanization intensified, driven primarily by a reduction in rare taxa. Despite a stable core microbiome dominated by a few taxa, the overall community structure varied significantly along the urban gradient, with notable shifts in dominant fungal taxa. Contrary to expectations, no detectable levels of heavy metals were found in water samples, suggesting that other urbanization-related factors, potentially including organic pollutants or plant stress responses, influence fungal endophyte communities. Our findings underscore the need for further investigation into the mechanisms driving these patterns, particularly the roles of organic pollution, nutrient loads, and plant stress. Understanding these interactions is crucial for predicting the impacts of continued urbanization on freshwater ecosystems and their associated microbial communities.

ecology↗

bioRxiv2022

Inclusion of database outgroups improves accuracy of fungal meta-amplicon taxonomic assignments

Meta-amplicon studies of fungal communities rely on curated databases for assigning taxonomy. Any host or other non-fungal environmental sequences that are amplified during PCR are inherently assigned taxonomy by these same databases, possibly leading to ambiguous non-fungal amplicons being assigned to fungal taxa. Here, we investigated the effects of including non-fungal outgroups in a fungal taxonomic database to aid in detecting and removing these non-target amplicons. We processed 15 publicly available fungal meta-amplicon data sets and discovered that roughly 40% of the reads from these studies were not fungal, though they were assigned as Fungus sp. when using a database without non-fungal outgroups. We discuss implications for meta-amplicon studies and recommend assigning taxonomy using a database with outgroups to better detect these non-fungal amplicons.

ecology↗

bioRxiv2022

The Mangrove Microbiome of the Malay Peninsula

Microbes have fundamental roles underpinning the functioning of our planet, they are involved in global carbon and nutrient cycling, and support the existence of multicellular life. The mangrove ecosystem is nutrient limited and without microbial cycling, life in this harsh environment would likely not exist. The mangroves of Southeast Asia are the oldest and most biodiverse of all the planets. They have vital roles helping to prevent shoreline erosion, act as nursery grounds for many marine species and contain significant stocks of sequestered carbon. Despite these recognised benefits and the importance of microbes in these ecosystems, studies examining the mangrove microbiome are scarce, especially in the Southeast Asian biodiversity hotspot. Here we examine the microbiome of Avicenia alba and Sonneratia alba and identify a core microbiome of 81 taxa, a further eight taxa (Pleurocapsa, Tunicatimonas, Halomonas, Marinomonas, Rubrivirga, Altererythrobacte, Lewinella, and Erythrobacter) were found to be differentially abundant suggesting key roles in this microbiome, with the identified dimethylsulfoniopropionate (DMSP) metabolisers having important functions in these habitats. The majority of those identified are involved in nutrient cycling or involved in the production of compounds that promote host survival. Increasingly, blue carbon and nature-based solutions to climate change are heralded as viable mitigation steps to limit climate change, however, this is done with little to no consideration of the microbial communities that cycle sequestered carbon in these environments. Here, we examine the microbial communities present in sediment samples taken in close proximity to each tree, sediment samples represent a major sink of atmospheric carbon and understanding how the associated communities will change as climate change advances will become an increasingly important part of carbon stock assessments. Knowing what microbes are presently there is an important first step in this process.

ecology↗

bioRxiv2020

Long-term soil fungal community recovery after fire is impacted by climate change

Though much is known about fungal importance to forest health, there is very little information about factors that impact soil fungal community recovery time after a fire. Soil samples were taken from burn sites within one ecotype of temperate coniferous forest in Utah over a 20-year chronosequence. Sites were selected from available historic burns and were similar in plant community structure, elevation, slope, and aspect. Fungal DNA from these samples was compared to soil from paired unburned sites nearby to measure community similarity and estimate soil fungal recovery rates. Differences between paired burned and unburned sites remained fairly stable over a decadal time scale overall, but fungal community structure was found to recover more quickly in areas with a higher average annual temperatures. A significant positive correlation in community recovery was seen in areas with a difference of as little as two degrees celsius per year. The only other environmental variable that significantly interacted with time since burn was annual mean precipitation. As global temperatures increase, alpine fires are increasing as well, but these results suggest that fungal community recovery time will be shortened under new climate scenarios.

ecology↗

bioRxiv2019

Fungal communities living within leaves of native Hawaiian dicots are structured by landscape-scale variables as well as by host plants

ABSTRACTA phylogenetically diverse array of fungi live within healthy leaf tissue of dicotyledonous plants. Many studies have examined these endophytes within a single plant species and/or at small spatial scales, but landscape-scale variables that determine their community composition are not well understood, either across geographic space, across climatic conditions, or in the context of host plant phylogeny. Here, we evaluate the contributions of these variables to endophyte beta diversity using a survey of foliar endophytic fungi in native Hawaiian dicots sampled across the Hawaiian archipelago. We used Illumina technology to sequence fungal ITS1 amplicons to characterize foliar endophyte communities across five islands and 80 host plant genera. We found that communities of foliar endophytic fungi showed strong geographic structuring between distances of seven and 36 km. Endophyte community structure was most strongly associated with host plant phylogeny and evapotranspiration, and was also significantly associated with NDVI, elevation, and solar radiation. Additionally, our bipartite network analysis revealed that the five islands we sampled each harbored significantly specialized endophyte communities. These results demonstrate how the interaction of factors at large and small spatial and phylogenetic scales shape fungal symbiont communities.Competing Interest StatementThe authors have declared no competing interest.View Full Text

ecology↗