Experimental evolution of bet hedging
read more
Citations
Functional roles for noise in genetic circuits
Cellular decision making and biological noise: from microbes to mammals.
Early developmental conditioning of later health and disease: physiology or pathophysiology?
Cellular Decision Making and Biological Noise: From Microbes to Mammals
A functional perspective on phenotypic heterogeneity in microorganisms
References
The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme
The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme
Accurate whole human genome sequencing using reversible terminator chemistry
Somatic generation of antibody diversity
Bacterial Persistence as a Phenotypic Switch
Related Papers (5)
Phenotypic Diversity, Population Growth, and Information in Fluctuating Environments
Stochastic switching as a survival strategy in fluctuating environments.
Frequently Asked Questions (14)
Q2. What is the general prediction from theory?
The general prediction from theory is that fluctuating selection generated by unpredictable environments can favour the evolution of bet hedging1–4,12–14.
Q3. How many replicate selection lines were founded with the ancestral genotype?
Twelve replicate selection lines were founded with the ancestral genotype and subjected to 16 rounds of alternating selection in static and shaken microcosms.
Q4. What is the significance of the experiment?
The rapid and repeatable evolution of bet hedging during their experiment suggests it may have been among the earliest evolutionary solutions to life in variable environments, perhaps even preceding the evolution of environmentally responsive mechanisms of gene regulation.
Q5. What is the reason for the evolution of colony switching?
If the carB mutation is the sole cause of the evolution of colony switching from 1A4, it must confer not only colony switching but also the requisite high fitness in static microcosms in this genetic background.
Q6. What was the evolution of bet hedging in experimental bacterial populations?
During each round, populations were propagated by serial dilution until the emergence of cells that formed colonies with a heritable morphology different from that of their immediate ancestor.
Q7. What was the effect of the exclusion rule on the populations?
Their populations experienced repeated bouts of selection in two contrasting environments; they also experienced fluctuating selection wrought by imposition of an exclusion rule and population bottleneck.
Q8. What did the authors find out about the evolution of 1A4?
The authors conclude that the evolutionary history of 1A4 ‘set the stage’ for the evolution of stochastic colony morphology switching by altering the relative fitness effect of the carB mutation.
Q9. What is the probability of observing this pattern under the null hypothesis?
The probability of observing this pattern under the null hypotheses of no reversible switching is exceedingly low (one-tailed Fisher’s exact test, P 5 0.0004; see Supplementary Note 3), indicating that 1B4 switches reversibly between Cap1 and Cap2.
Q10. How was the whole genome of 1B4 analysed?
Using whole-genome re-sequencing21,22, the entire 6.7-megabasepair genome of 1B4 (ref. 23) was analysed to unravel its mutational history.
Q11. What is the alternative to bet hedging?
An alternative solution is stochastic phenotype switching, a strategy based on bet hedging, rather than direct environmental sensing4–10.
Q12. What was the final mutation for bet hedging?
The final mutation was both necessary and sufficient for rapid phenotype switching; nonetheless, the evolution of bet hedging was contingent upon earlier mutations that altered the relative fitness effect of the final mutation.
Q13. How many mutations were separating 1B4 from the original ancestor?
Nine mutations separating 1B4 from the original ancestor were identified, confirmed by Sanger sequencing, and ordered by inspection of the affected loci in the preceding genotypes (Fig. 3b).
Q14. What was the effect of the exclusion rule on the selection of bacterial colonies?
the authors imposed selection for a high growth rate in static and shaken microcosms, and simultaneously fluctuating selection for colony innovation.