{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,27]],"date-time":"2026-07-27T06:01:50Z","timestamp":1785132110619,"version":"3.55.0"},"reference-count":42,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,7,27]],"date-time":"2026-07-27T00:00:00Z","timestamp":1785110400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Microbiol."],"abstract":"<jats:p>\n                    Climate warming accelerates glacial meltwater delivery to Arctic lakes, mobilizing metals from thawing catchments and reshaping the selective landscape experienced by resident microbes. Whether these gradients leave detectable signatures of diversification in environmental resistance genes remains unclear. We investigated four metal resistance genes (\n                    <jats:italic>merA<\/jats:italic>\n                    ,\n                    <jats:italic>arsC<\/jats:italic>\n                    ,\n                    <jats:italic>cadA<\/jats:italic>\n                    , and\n                    <jats:italic>chrR<\/jats:italic>\n                    ) in metagenomic datasets from Lake Hazen (Nunavut, Canada), the largest High Arctic freshwater lake, sampled across a natural hydrological gradient of Control, Low-runoff, and High-runoff regimes. Using a space-for-time substitution design, we combined population-genetic and codon-based approaches to quantify diversity and candidate selection signals, including nucleotide diversity, Tajima\u2019s\n                    <jats:italic>D<\/jats:italic>\n                    , non-synonymous-to-synonymous diversity ratios, McDonald-Kreitman tests with outgroup-sensitivity analysis, site-level episodic selection (MEME with false-discovery-rate correction), and gene-wide tests (BUSTED and BUSTED-E) and complemented these with ortholog clustering, within-clade re-analysis, taxonomic profiling, rarefaction, and phylogenetic beta-diversity. Marked heterogeneity emerged among genes:\n                    <jats:italic>merA<\/jats:italic>\n                    showed increasing diversity and patterns consistent with diversification along the runoff gradient, and these signals were preserved within the largest orthologous cluster (90% of haplotypes), supporting an interpretation of within-orthogroup diversification;\n                    <jats:italic>cadA<\/jats:italic>\n                    displayed the strongest McDonald-Kreitman signal under low and high runoff, but its gene-wide BUSTED-E signal collapsed within a single ortholog cluster, suggesting that part of the apparent diversifying signal at the gene-family level reflects inter-subfamily heterogeneity;\n                    <jats:italic>chrR<\/jats:italic>\n                    exhibited the strongest regime structure but its largest orthologous cluster was dominated by Control sequences and 93% of High-regime haplotypes were affiliated with a single bacterial order (Hyphomicrobiales), indicating that the regime contrast for this gene reflects compositional turnover rather than within-lineage evolution;\n                    <jats:italic>arsC<\/jats:italic>\n                    remained largely consistent with neutral or purifying evolution across regimes. Because these inferences derive from metagenomic gene pools sampled across only three hydrological regimes and aggregate variants across taxa, we interpret them as exploratory, hypothesis-generating patterns rather than as demonstrations of population-level adaptation. Our findings highlight environmental resistance genes as candidate indicators of changing biogeochemical conditions in rapidly warming polar ecosystems, while underscoring the importance of orthology and community-composition controls when inferring selection from metagenomic data.\n                  <\/jats:p>","DOI":"10.3389\/fmicb.2026.1903619","type":"journal-article","created":{"date-parts":[[2026,7,27]],"date-time":"2026-07-27T05:41:04Z","timestamp":1785130864000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Glacial meltwater is associated with gene-specific diversification of metal resistance genes in high Arctic soil microbiomes"],"prefix":"10.3389","volume":"17","author":[{"given":"Franck J.","family":"Ouedraogo","sequence":"first","affiliation":[{"name":"Department of Biology, University of Ottawa","place":["Ottawa, ON, Canada"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alexandre J.","family":"Poulain","sequence":"additional","affiliation":[{"name":"Department of Biology, University of Ottawa","place":["Ottawa, ON, Canada"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"St\u00e9phane","family":"Aris-Brosou","sequence":"additional","affiliation":[{"name":"Department of Biology, University of Ottawa","place":["Ottawa, ON, Canada"]},{"name":"Department of Mathematics and Statistics, University of Ottawa","place":["Ottawa, ON, Canada"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,7,27]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"873","DOI":"10.1128\/AEM.70.2.873-882.2004","article-title":"Chromate-reducing properties of soluble flavoproteins from pseudomonas putida and Escherichia coli","volume":"70","author":"Ackerley","year":"2004","journal-title":"Appl. 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