Related Experiment Video
Updated: May 18, 2026
06:18
Frequency and Distribution of Crossovers in Caenorhabditis elegans Meiosis by SNP Genotyping using Real-time PCR
Published on: July 11, 2025
What is the evidence for heterozygote advantage selection?
1Arizona State University, Tempe, AZ 85287, USA. philip.hedrick@asu.edu
Trends in Ecology & Evolution
|September 15, 2012
Summary
Many genes show signs of selection, but few exhibit heterozygote advantage. This suggests heterozygote advantage, while potentially adaptive, plays a minor role in overall species evolution.
Area of Science:
- Evolutionary genetics
- Population genetics
- Genomics
Background:
- Genomic data reveal widespread signals of selection across genes.
- Understanding the prevalence of specific selection types, like heterozygote advantage, is crucial for evolutionary insights.
Purpose of the Study:
- To assess the proportion of genes experiencing heterozygote advantage selection.
- To determine the significance of heterozygote advantage in evolutionary adaptation.
Main Methods:
- Analysis of recent genomic data to identify genes under selection.
- Comparison of genomic survey results with other evolutionary approaches.
Main Results:
- Initial genomic surveys indicate a small fraction of loci are maintained by heterozygote advantage.
- This finding is consistent with limited evidence from other methods within species.
Conclusions:
- Heterozygote advantage loci appear to be a small minority of all loci in a species.
- While important for specific adaptations, heterozygote advantage may not be a major driver of overall evolutionary change.
Related Concept Videos
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...
01:49Hardy-Weinberg Principle
Diploid organisms have two alleles of each gene, one from each parent, in their somatic cells. Therefore, each individual contributes two alleles to the gene pool of the population. The gene pool of a population is the sum of every allele of all genes within that population and has some degree of variation. Genetic variation is typically expressed as a relative frequency, which is the percentage of the total population that has a given allele, genotype or phenotype.
01:21Frequency-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.
02:16Genetics of Speciation
Speciation is the evolutionary process resulting in the formation of new, distinct species—groups of reproductively isolated populations.
01:49Multiple Allele Traits
The Concept of Multiple Allelism
01:49Law of Segregation
When crossing pea plants, Mendel noticed that one of the parental traits would sometimes disappear in the first generation of offspring, called the F1 generation, and could reappear in the next generation (F2). He concluded that one of the traits must be dominant over the other, thereby causing masking of one trait in the F1 generation. When he crossed the F1 plants, he found that 75% of the offspring in the F2 generation had the dominant phenotype, while 25% had the recessive phenotype.