Long-Term Experimental Evolution and Adaptive Radiation

2009 ◽  
pp. 111-133 ◽  
Author(s):  
Michael Travisano
Keyword(s):  
Adaptive Radiation ◽  
Experimental Evolution

scholarly journals Long-Term Experimental Evolution in Escherichia coli. VI. Environmental Constraints on Adaptation and Divergence

Genetics ◽  
1997 ◽  
Vol 146 (2) ◽  
pp. 471-479 ◽  
Author(s):  
Michael Travisano
Keyword(s):  
Escherichia Coli ◽  
Genetic Variation ◽  
Experimental Evolution ◽  
Population Genetic ◽  
Environmental Constraints ◽  
Asymmetric Pattern ◽  
Nutrient Environment ◽  
Mean Fitness ◽  
Population Genetic Variation

The effect of environment on adaptation and divergence was examined in two sets of populations of Escherichia coli selected for 1000 generations in either maltose- or glucose-limited media. Twelve replicate populations selected in maltose-limited medium improved in fitness in the selected environment, by an average of 22.5%. Statistically significant among-population genetic variation for fitness was observed during the course of the propagation, but this variation was small relative to the fitness improvement. Mean fitness in a novel nutrient environment, glucose-limited medium, improved to the same extent as in the selected environment, with no statistically significant among-population genetic variation. In contrast, 12 replicate populations previously selected for 1000 generations in glucose-limited medium showed no improvement, as a group, in fitness in maltose-limited medium and substantial genetic variation. This asymmetric pattern of correlated responses suggests that small changes in the environment can have profound effects on adaptation and divergence.

scholarly journals Long-Term Experimental Evolution in Escherichia coli. IV. Targets of Selection and the Specificity of Adaptation

Genetics ◽  
1996 ◽  
Vol 143 (1) ◽  
pp. 15-26 ◽  
Author(s):  
Michael Travisano ◽  
Richard E Lenski
Keyword(s):  
Escherichia Coli ◽  
Experimental Evolution ◽  
Common Ancestor ◽  
The Novel ◽  
Physiological Mechanisms ◽  
Outer Membranes ◽  
Limiting Nutrient ◽  
Novel Environments ◽  
Uptake Mechanisms

Abstract This study investigates the physiological manifestation of adaptive evolutionary change in 12 replicate populations of Escherichia coli that were propagated for 2000 generations in a glucose-limited environment. Representative genotypes from each population were assayed for fitness relative to their common ancestor in the experimental glucose environment and in 11 novel single-nutrient environments. After 2000 generations, the 12 derived genotypes had diverged into at least six distinct phenotypic classes. The nutrients were classified into four groups based upon their uptake physiology. All 12 derived genotypes improved in fitness by similar amounts in the glucose environment, and this pattern of parallel fitness gains was also seen in those novel environments where the limiting nutrient shared uptake mechanisms with glucose. Fitness showed little or no consistent improvement, but much greater genetic variation, in novel environments where the limiting nutrient differed from glucose in its uptake mechanisms. This pattern of fitness variation in the novel nutrient environments suggests that the independently derived genotypes adapted to the glucose environment by similar, but not identical, changes in the physiological mechanisms for moving glucose across both the inner and outer membranes.

scholarly journals Adaptation and competition in deteriorating environments

2021 ◽  
Vol 288 (1946) ◽  
pp. 20202967
Author(s):  
Romana Limberger ◽  
Gregor F. Fussmann
Keyword(s):  
Salt Stress ◽  
Experimental Evolution ◽  
Competitive Ability ◽  
High Salt ◽  
Competitive Interactions ◽  
Complex Interplay ◽  
Population Growth Rates ◽  
Changing Environments ◽  
History Of

Evolution might rescue populations from extinction in changing environments. Using experimental evolution with microalgae, we investigated if competition influences adaptation to an abiotic stressor, and vice versa, if adaptation to abiotic change influences competition. In a first set of experiments, we propagated monocultures of five species with and without increasing salt stress for approximately 180 generations. When assayed in monoculture, two of the five species showed signatures of adaptation, that is, lines with a history of salt stress had higher population growth rates at high salt than lines without prior exposure to salt. When assayed in mixtures of species, however, only one of these two species had increased population size at high salt, indicating that competition can alter how adaptation to abiotic change influences population dynamics. In a second experiment, we cultivated two species in monocultures and in pairs, with and without increasing salt. While we found no effect of competition on adaptation to salt, our experiment revealed that evolutionary responses to salt can influence competition. Specifically, one of the two species had reduced competitive ability in the no-salt environment after long-term exposure to salt stress. Collectively, our results highlight the complex interplay of adaptation to abiotic change and competitive interactions.

scholarly journals The Odyssey of the Ancestral Escherich Strain through Culture Collections: an Example of Allopatric Diversification

mSphere ◽  
2018 ◽  
Vol 3 (1) ◽  
Author(s):  
M. Desroches ◽  
G. Royer ◽  
D. Roche ◽  
M. Mercier-Darty ◽  
D. Vallenet ◽  
...  
Keyword(s):  
Experimental Evolution ◽  
Efflux Pump ◽  
Strain History ◽  
Culture Collections ◽  
E Coli ◽  
Molecular Features ◽  
Natural Isolates ◽  
History Of ◽  
Encoding Genes

Mutator phenotypes have been described in laboratory-evolved bacteria, as well as in natural isolates. Several genes can be impacted, each of them being associated with a typical mutational spectrum. By studying one of the oldest strains available, the ancestral Escherich strain, we were able to identify its mutator status leading to tremendous genetic diversity among the isolates from various collections and allowing us to reconstruct the phylogeographic history of the strain. This mutator phenotype was probably acquired during the storage of the strain, promoting adaptation to a specific environment. Other mutations inrpoSand efflux pump- and porin-encoding genes highlight the acclimatization of the strain through self-preservation and nutritional competence regulation. This strain history can be viewed as unintentional experimental evolution in culture collections all over the word since 1885, mimicking the long-term experimental evolution ofE. coliof Lenski et al. (O. Tenaillon, J. E. Barrick, N. Ribeck, D. E. Deatherage, J. L. Blanchard, A. Dasgupta, G. C. Wu, S. Wielgoss, S. Cruveiller, C. Médigue, D. Schneider, and R. E. Lenski, Nature 536:165–170, 2016, https://doi.org/10.1038/nature18959) that shares numerous molecular features.

scholarly journals Using long-term experimental evolution to uncover the patterns and determinants of molecular evolution of anEscherichia colinatural isolate in the streptomycin-treated mouse gut

2016 ◽  
Vol 26 (7) ◽  
pp. 1802-1817 ◽  
Author(s):  
Mathilde Lescat ◽  
Adrien Launay ◽  
Mohamed Ghalayini ◽  
Mélanie Magnan ◽  
Jérémy Glodt ◽  
...  
Keyword(s):  
Molecular Evolution ◽  
Experimental Evolution ◽  
Treated Mouse

scholarly journals Gene-level quantitative trait mapping in an expandedC. elegansmultiparent experimental evolution panel

2019 ◽  
Author(s):  
Luke M. Noble ◽  
Matthew V. Rockman ◽  
Henrique Teotónio
Keyword(s):  
Experimental Evolution ◽  
Recombinant Inbred Lines ◽  
Single Gene ◽  
Ancestral Population ◽  
C Elegans ◽  
Quantitative Trait Mapping ◽  
Trait Variance ◽  
Gene Level ◽  
Evolution Experiment

ABSTRACTTheCaenorhabditis elegansmultiparental experimental evolution (CeMEE) panel is a collection of genome-sequenced, cryopreserved recombinant inbred lines useful for mapping the genetic basis and evolution of quantitative traits. We have expanded the resource with new lines and new populations, and here report updated additive and epistatic mapping simulations and the genetic and haplotypic composition of CeMEE version 2. Additive QTL explaining 3% of trait variance are detected with >80% power, and the median detection interval is around the length of a single gene on the highly recombinant chromosome arms. Although CeMEE populations are derived from a long-term evolution experiment, genetic structure is dominated by variation present in the ancestral population and is not obviously associated with phenotypic differentiation.C. elegansprovides exceptional experimental advantages for the study of phenotypic evolution.

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