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High level of intergenera gene exchange shapes the evolution of haloarchaea in an isolated Antarctic lake

Citation

DeMaere, MZ and Williams, TJ and Allen, MA and Brown, MV and Gibson, JAE and Rich, J and Lauro, FM and Dyall-Smith, M and Davenport, KW and Woyke, T and Kyrpides, NC and Tringe, SG and Cavicchioli, R, High level of intergenera gene exchange shapes the evolution of haloarchaea in an isolated Antarctic lake, National Academy of Sciences Proceedings, 110, (42) pp. 16939-16944. ISSN 0027-8424 (2013) [Refereed Article]


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Copyright 2013 The Authors

DOI: doi:10.1073/pnas.1307090110

Abstract

Deep Lake in Antarctica is a globally isolated, hypersaline system that remains liquid at temperatures down to −20 °C. By analyzing metagenome data and genomes of four isolates we assessed genome variation and patterns of gene exchange to learn how the lake community evolved. The lake is completely and uniformly dominated by haloarchaea, comprising a hierarchically structured, low-complexity community that differs greatly to temperate and tropical hypersaline environments. The four Deep Lake isolates represent distinct genera (∼85% 16S rRNA gene similarity and ∼73% genome average nucleotide identity) with genomic characteristics indicative of niche adaptation, and collectively account for ∼72% of the cellular community. Network analysis revealed a remarkable level of intergenera gene exchange, including the sharing of long contiguous regions (up to 35 kb) of high identity (∼100%). Although the genomes of closely related Halobacterium, Haloquadratum, and Haloarcula (>90% average nucleotide identity) shared regions of high identity between species or strains, the four Deep Lake isolates were the only distantly related haloarchaea to share long high-identity regions. Moreover, the Deep Lake high-identity regions did not match to any other hypersaline environment metagenome data. The most abundant species, tADL, appears to play a central role in the exchange of insertion sequences, but not the exchange of high-identity regions. The genomic characteristics of the four haloarchaea are consistent with a lake ecosystem that sustains a high level of intergenera gene exchange while selecting for ecotypes that maintain sympatric speciation. The peculiarities of this polar system restrict which species can grow and provide a tempo and mode for accentuating gene exchange.

Item Details

Item Type:Refereed Article
Keywords:bacteria, Deep Lake, Halobacterium
Research Division:Biological Sciences
Research Group:Genetics
Research Field:Molecular Evolution
Objective Division:Environment
Objective Group:Flora, Fauna and Biodiversity
Objective Field:Antarctic and Sub-Antarctic Flora, Fauna and Biodiversity
Author:Gibson, JAE (Dr John Gibson)
ID Code:88990
Year Published:2013
Web of Science® Times Cited:43
Deposited By:IMAS Research and Education Centre
Deposited On:2014-02-22
Last Modified:2015-01-27
Downloads:319 View Download Statistics

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