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ABSTRACT Humans are changing habitat for wildlife in myriad ways and for populations to persist, they must adapt to this change. In parts of the world that experience snow and ice, road salts are often used to make driving safer in the winter. Runoff from these roads increases the salinity in nearby bodies of water, which has been shown to have detrimental physiological and ecological effects in freshwater ecosystems; however, the evolutionary consequences of salinization remain unclear.Tetrahymenaare microbial eukaryotes that live in freshwater habitats and serve as an important link in the microbial food loop. In this study, we tested howT. thermophilacan evolve in response to increasing concentrations of road salts in their environment. Using experimental evolution, we found thatT. thermophilapopulations adapted to survive and grow in concentrations of up to 18 g/L of NaCl and 17 g/L MgCl2, approximately twice the salinity tolerance of ancestral populations. However, populations adapted to the highest salt concentrations experience fitness trade‐offs of reduced survival and growth rate and longer lag times when grown in salt‐free environments. These results demonstrate the rapidity with which microbial populations can respond to anthropogenic changes to their environment, yet highlight the potential costs associated with this adaptation.
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This content will become publicly available on April 1, 2027
Activity‐Informed Network Analysis Reveals Keystone Microbes Shaping Freshwater Ecosystem Function
ABSTRACT Freshwater lakes are dynamic ecosystems, with varying oxygen dynamics that influence microbiome structure, composition, and transcriptomic activity. In many freshwater studies, ecological function and abundance metrics are used to discover keystone species; however, it is well established that abundance does not equal activity. Despite the existence of long‐term time series spanning multiple years, no previous study has looked at how microbial community and activity (metatranscriptomics) are influenced by shifting oxygen conditions across depths at the microbial network level. In this study, we leverage metagenome‐assembled genomes and transcriptomic activity to identify keystone taxa in the ecosystem. Using theSPIEC‐EASIandCARlassomethods, we mapped key microbial associations and used permutation‐based analyses to assess the robustness of keystone identification. Our results reveal that a taxon's ecological centrality is context‐dependent and that many species identified as keystone by abundance alone do not exhibit corresponding transcriptional activity. Notably, members of Bacteroidota and other lineages emerged as keystone taxa only when both abundance and activity were considered. Our study underscores the importance of combining metagenomic and metatranscriptomic approaches for accurate identification of functionally relevant keystone species in freshwater ecosystems, providing a framework for future microbial ecology studies.
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- PAR ID:
- 10678433
- Publisher / Repository:
- Environmental Microbiology
- Date Published:
- Journal Name:
- Environmental Microbiology Reports
- Volume:
- 18
- Issue:
- 2
- ISSN:
- 1758-2229
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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