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Adaptation at the Extremes of Life: Experimental Evolution with the Extremophile Archaeon Sulfolobus acidocaldarius
Published on: June 14, 2024
Parallel adaptations to high temperatures in the Archaean eon.
Bastien Boussau1, Samuel Blanquart, Anamaria Necsulea
1Laboratoire de Biométrie et Biologie Evolutive, CNRS, Université de Lyon, Université Lyon I, 43 Boulevard du 11 Novembre, 69622 Villeurbanne, France.
Nature
|November 28, 2008
Summary
The last universal common ancestor (LUCA) was likely mesophilic, with Bacteria and Archaea-Eukaryota ancestors later convergently adapting to high temperatures. Thermotolerance then decreased in these lineages over evolutionary time.
Area of Science:
- Evolutionary Biology
- Genomics
- Biochemistry
Background:
- Interpreting early life fossils is challenging, necessitating alternative methods to study ancestral ecologies.
- Genetic footprints in extant genomes offer insights into ancestral organism temperatures.
- Previous studies yielded conflicting hypotheses regarding the last universal common ancestor's (LUCA) thermal environment.
Purpose of the Study:
- To investigate the thermal evolution of early life using molecular data.
- To reconcile contradictory findings on LUCA's temperature and ancestral thermotolerance.
- To reconstruct the temperature adaptation phases in the early tree of life.
Main Methods:
- Analysis of both ribosomal RNA (rRNA) and protein sequences.
- Application of advanced, realistic models of molecular evolution.
- Reconstruction of ancestral thermal adaptation based on genomic data.
Main Results:
- Evidence supports two distinct temperature-related evolutionary phases.
- Thermotolerance increased from a mesophilic LUCA to thermophilic bacterial and archaeal-eukaryotic ancestors.
- Thermotolerance subsequently decreased, indicating convergent adaptations to high temperatures.
Conclusions:
- The LUCA was likely mesophilic, not thermophilic.
- Ancestors of Bacteria and Archaea-Eukaryota convergently adapted to high temperatures, possibly due to climate change or genome transitions.
- This study provides a unified view of early life's thermal evolution.
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