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Frequency-dependent Selection

Frequency-dependent Selection

When the fitness of a trait is influenced by how common it is (i.e., its frequency) relative to different traits within a population, this is referred to as frequency-dependent selection. Frequency-dependent selection may occur between species or within a single species. This type of selection can either be positive—with more common phenotypes having higher fitness—or negative, with rarer phenotypes conferring increased fitness.

Limits to Natural Selection

Limits to Natural Selection

Organisms that are well-adapted to their environment are more likely to survive and reproduce. However, natural selection does not lead to perfectly adapted organisms. Several factors constrain natural selection.

Types of Selection

Types 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...

Conservation of Small Populations

Conservation of Small Populations

Small population sizes put a species at extreme risk of extinction due to a lack of variation, and a consequent decrease in adaptability. This weakens the chances of survival under pressures such as climate change, competition from other species, or new diseases. Large populations are more likely to survive pressures such as these, as such populations are more likely to harbor individuals that have genetic variants that are adaptive under new stresses. Small populations are much less...

Pedigree Analysis

Pedigree Analysis

Genetic Drift

Genetic Drift

Natural selection—probably the most well-known evolutionary mechanism—increases the prevalence of traits that enhance survival and reproduction. However, evolution does not merely propagate favorable traits, nor does it always benefit populations.

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Navigating MARRVEL, a Web-Based Tool that Integrates Human Genomics and Model Organism Genetics Information

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Negative selection on complex traits limits phenotype prediction accuracy between populations.

Arun Durvasula¹, Kirk E Lohmueller²

¹Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.

American Journal of Human Genetics

|March 10, 2021

Summary

This summary is machine-generated.

Most genetic studies focus on European populations, limiting phenotype prediction accuracy in others. This study reveals population-specific genetic architectures due to demographic history and selection, impacting polygenic score utility.

Keywords:

complex traits negative selection polygenic scores population genetics population history risk prediction simulations

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Area of Science:

Genetics
Population Genetics
Medical Genetics

Background:

Genome-wide association studies (GWAS) are predominantly conducted in European populations.
This population bias leads to reduced accuracy of polygenic scores in non-European populations.
Human demographic history and negative selection can create population-specific genetic architectures.

Purpose of the Study:

To investigate how demographic history and negative selection influence population-specific genetic architectures.
To determine the impact of these architectures on phenotype prediction accuracy across diverse populations.
To empirically test predictions using real-world genetic data.

Main Methods:

Utilized population genetic models to simulate genetic architectures.
Developed a model to stratify heritability between European-specific and shared variants.
Applied the model to 37 traits and diseases using UK Biobank data.

Main Results:

Population-specific genetic architectures arise from demographic history and negative selection.
For traits under strong negative selection, European-specific variants account for significant heritability (up to 50%).
Empirically, approximately 30% of heritability for 37 phenotypes in UK Biobank derived from European-specific variants.

Conclusions:

Genetic association studies require greater population diversity to improve phenotype prediction utility globally.
Current polygenic scores may fail to identify at-risk individuals in non-European populations.
Addressing genetic architecture disparities is crucial for equitable medical genetics applications.