1. Microbial DNA records historical delivery of anthropogenic mercury.
- Author
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Poulain AJ, Aris-Brosou S, Blais JM, Brazeau M, Keller WB, and Paterson AM
- Subjects
- Amino Acid Sequence, Bacteria classification, Bacteria isolation & purification, Bacteria metabolism, Bacterial Proteins genetics, Bacterial Proteins metabolism, Ecosystem, Environmental Pollutants metabolism, Environmental Pollution history, Geologic Sediments chemistry, Geologic Sediments microbiology, History, 19th Century, History, 20th Century, Humans, Mercury metabolism, Molecular Sequence Data, Oxidoreductases genetics, Oxidoreductases metabolism, Phylogeny, Sequence Alignment, Bacteria genetics, DNA, Bacterial genetics, Environmental Pollutants analysis, Mercury analysis
- Abstract
Mercury (Hg) is an anthropogenic pollutant that is toxic to wildlife and humans, but the response of remote ecosystems to globally distributed Hg is elusive. Here, we use DNA extracted from a dated sediment core to infer the response of microbes to historical Hg delivery. We observe a significant association between the mercuric reductase gene (merA) phylogeny and the timing of Hg deposition. Using relaxed molecular clock models, we show a significant increase in the scaled effective population size of the merA gene beginning ~200 years ago, coinciding with the Industrial Revolution and a coincident strong signal for positive selection acting on residues in the terminal region of the mercuric reductase. This rapid evolutionary response of microbes to changes in the delivery of anthropogenic Hg indicates that microbial genomes record ecosystem response to pollutant deposition in remote regions.
- Published
- 2015
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