Related Experiment Video
Updated: Aug 10, 2026
10:17
An Allele-specific Gene Expression Assay to Test the Functional Basis of Genetic Associations
Published on: November 3, 2010
Summary
Genetic drift drives evolution at the molecular level, even with strong stabilizing selection. Alleles with small effects are neutral, explaining neutral molecular evolution.
Area of Science:
- Evolutionary biology
- Population genetics
- Molecular evolution
Background:
- Genetic drift is a key evolutionary mechanism.
- Stabilizing selection acts to maintain optimal phenotypes.
- The neutral theory of molecular evolution posits that most molecular changes are neutral.
Purpose of the Study:
- To identify conditions favoring evolution by genetic drift.
- To analyze the role of allele effects under stabilizing selection.
- To provide a mechanistic basis for neutral molecular evolution.
Main Methods:
- Derivation of the selection coefficient for alleles of arbitrary effect.
- Analysis of polygenic characters under stabilizing selection.
- Investigation of selection-drift-mutation equilibrium.
Main Results:
- Alleles with an average effect < 10(-2) phenotypic standard deviations are effectively neutral.
- Significant neutral evolution is expected for intermediate-effect alleles at equilibrium.
- Genetic drift can operate even under strong directional or stabilizing selection.
Conclusions:
- Clarifies the occurrence of molecular evolution via genetic drift.
- Offers a mechanistic explanation supporting the neutral theory of molecular evolution.
- Highlights the importance of allele effect size in evolutionary dynamics.
Related Concept Videos
01:49Multiple Allele Traits
The Concept of Multiple Allelism
01:18Polygenic Traits
When more than one gene is responsible for a given phenotype, the trait is considered polygenic. Human height is a polygenic trait. Studies have uncovered hundreds of loci that influence height, and there are believed to be many more. Due to the high number of genes involved, as well as environmental and nutritional factors, height varies significantly within a given population. The distribution of height forms a bell-shaped curve, with relatively few individuals in the population at the...
01:46Types of Selection
Natural selection influences the frequencies of particular alleles and phenotypes within populations in several different ways. Primarily, natural selection can be directional, stabilizing, or disruptive. Directional selection favors one extreme trait and shifts the population towards that phenotype while selecting against individuals displaying alternate traits. Stabilizing selection favors an intermediate trait with a narrow range of variation. Deviation from the optimal phenotype towards an...
01:49Multiple Allele Traits
The Concept of Multiple Allelism
01:18Polygenic Traits
When more than one gene is responsible for a given phenotype, the trait is considered polygenic. Human height is a polygenic trait. Studies have uncovered hundreds of loci that influence height, and there are believed to be many more. Due to the high number of genes involved, as well as environmental and nutritional factors, height varies significantly within a given population. The distribution of height forms a bell-shaped curve, with relatively few individuals in the population at the...
01:09Epistasis Analysis
Although Mendel chose seven unrelated traits in peas to study gene segregation, most traits involve multiple gene interactions that create a spectrum of phenotypes. When the interaction of various genes or alleles at different locations influences a phenotype, this is called epistasis. Epistasis often involves one gene masking or interfering with the expression of another (antagonistic epistasis). Epistasis often occurs when different genes are part of the same biochemical pathway. The...