Impacto da epistase e pleiotropia na adaptação evolucionária

quinta-feira, junho 23, 2011

Impact of epistasis and pleiotropy on evolutionary adaptation

Bjørn Østman1,2,3,*, Arend Hintze1,3,4 and Christoph Adami1,2,3

Author Affiliations

1Keck Graduate Institute of Applied Life Sciences, Claremont, CA 91711, USA

2Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48823, USA

3BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI 48823, USA

4Department of Computer Science and Engineering, Michigan State University, East Lansing, MI 48823, USA

*Author for correspondence (


Evolutionary adaptation is often likened to climbing a hill or peak. While this process is simple for fitness landscapes where mutations are independent, the interaction between mutations (epistasis) as well as mutations at loci that affect more than one trait (pleiotropy) are crucial in complex and realistic fitness landscapes. We investigate the impact of epistasis and pleiotropy on adaptive evolution by studying the evolution of a population of asexual haploid organisms (haplotypes) in a model ofN interacting loci, where each locus interacts with K other loci. We use a quantitative measure of the magnitude of epistatic interactions between substitutions, and find that it is an increasing function of K. When haplotypes adapt at high mutation rates, more epistatic pairs of substitutions are observed on the line of descent than expected. The highest fitness is attained in landscapes with an intermediate amount of ruggedness that balance the higher fitness potential of interacting genes with their concomitant decreased evolvability. Our findings imply that the synergism between loci that interact epistatically is crucial for evolving genetic modules with high fitness, while too much ruggedness stalls the adaptive process.

evolution, epistasis, gene networks, strong mutation

Received April 28, 2011.
Accepted June 2, 2011.
This Journal is © 2011 The Royal Society


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