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Pervasive, yet idiosyncratic, epistatic pleiotropy during adaptation in a behaviourally complex microbe.
P C Zee1, J Liu1, G J Velicer1
1Department of Biology, Indiana University, Bloomington, IN, USA.
Journal of Evolutionary Biology
|November 19, 2016
Summary
Evolutionary adaptation involves complex interactions between mutations, pleiotropy, and epistasis. These relationships change over time, impacting bacterial social traits and organismal fitness.
Area of Science:
- Evolutionary Biology
- Microbial Genetics
- Quantitative Genetics
Background:
- Understanding how multiple mutations jointly affect organismal fitness and adaptation is crucial.
- Pleiotropy (one gene affecting multiple traits) and epistasis (gene interactions) complicate genotype-to-phenotype relationships.
- How these interactions evolve over time remains largely unknown.
Purpose of the Study:
- To investigate the evolution of epistasis and pleiotropy interactions.
- To examine how mutations affecting social motility in Myxococcus xanthus pleiotropically impact other social traits.
- To determine how these pleiotropic effects change over evolutionary time.
Main Methods:
- Experimental evolution of Myxococcus xanthus on soft agar.
- Assessing pleiotropic effects of evolved mutations on hard agar motility, predation, and spore production.
- Analyzing the temporal dynamics of epistatic interactions across multiple traits.
Main Results:
- Pleiotropic effects of mutations varied significantly in direction and magnitude over evolutionary time.
- The expression of a known epistatic interaction differed across traits (motility, predation, sporulation).
- Phenotypic correlations between traits changed dynamically throughout the experiment.
Conclusions:
- 'Epistatic pleiotropy' is highly dynamic, varying in magnitude and sign across traits and time.
- Studying adaptation requires simultaneous consideration of evolving pleiotropy and epistasis.
- This highlights the complexity of genotype-phenotype mapping during evolution.
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