The Effects of Stabilizing and Directional Selection on Phenotypic and Genotypic Variation in a Population of RNA Enzymes

• DOI: 10.1007/s00239-013-9604-x
• Publication Date: 2013-12-05T06:43:28Z
• Authors: Eric J. Hayden; Sinisa Bratulic; Iwo Koenig; Evandro Ferrada; Andreas Wagner
• Keywords: 0301 basic medicine; 570; Genotype; Molecular Sequence Data; directional selection; Azoarcus; ribozymes; 576; Evolution, Molecular; 10127 Institute of Evolutionary Biology and Environmental Studies; 03 medical and health sciences; 1311 Genetics; 1312 Molecular Biology; RNA, Catalytic; experimental evolution; Selection, Genetic; Biology; 0303 health sciences; Base Sequence; Genetic Variation; genotype to phenotype; 1105 Ecology, Evolution, Behavior and Systematics; Phenotype; stabilizing selection; sequence space; 13. Climate action; 570 Life sciences; biology; 590 Animals (Zoology); Nucleic Acid Conformation

The distribution of variation in a quantitative trait and its underlying distribution of genotypic diversity can both be shaped by stabilizing and directional selection. Understanding either distribution is important, because it determines a population's response to natural selection. Unfortunately, existing theory makes conflicting predictions about how selection shapes these distributions, and very little pertinent experimental evidence exists. Here we study a simple genetic system, an evolving RNA enzyme (ribozyme) in which a combination of high throughput genotyping and measurement of a biochemical phenotype allow us to address this question. We show that directional selection, compared to stabilizing selection, increases the genotypic diversity of an evolving ribozyme population. In contrast, it leaves the variance in the phenotypic trait unchanged.