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Evolution of thermotolerance in hot spring cyanobacteria of the genus SynechococcusThe extension of ecological tolerance limits may be an important mechanism by which microorganisms adapt to novel environments, but it may come at the evolutionary cost of reduced performance under ancestral conditions. We combined a comparative physiological approach with phylogenetic analyses to study the evolution of thermotolerance in hot spring cyanobacteria of the genus Synechococcus. Among the 20 laboratory clones of Synechococcus isolated from collections made along an Oregon hot spring thermal gradient, four different 16S rRNA gene sequences were identified. Phylogenies constructed by using the sequence data indicated that the clones were polyphyletic but that three of the four sequence groups formed a clade. Differences in thermotolerance were observed for clones with different 16S rRNA gene sequences, and comparison of these physiological differences within a phylogenetic framework provided evidence that more thermotolerant lineages of Synechococcus evolved from less thermotolerant ancestors. The extension of the thermal limit in these bacteria was correlated with a reduction in the breadth of the temperature range for growth, which provides evidence that enhanced thermotolerance has come at the evolutionary cost of increased thermal specialization. This study illustrates the utility of using phylogenetic comparative methods to investigate how evolutionary processes have shaped historical patterns of ecological diversification in microorganisms.
Document ID
20040112734
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Miller, S. R.
(University of Oregon Eugene, Oregon 97403,)
Castenholz, R. W.
Date Acquired
August 21, 2013
Publication Date
October 1, 2000
Publication Information
Publication: Applied and environmental microbiology
Volume: 66
Issue: 10
ISSN: 0099-2240
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other

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