Related Experiment Video
Updated: Aug 11, 2026
06:18
Frequency and Distribution of Crossovers in Caenorhabditis elegans Meiosis by SNP Genotyping using Real-time PCR
Published on: July 11, 2025
Testing for segregation distortion in genetic scoring data from backcross or doubled haploid populations
1Molecular Genetics, Agriculture and Agri-Food Canada, Saskatoon Research Centre, 107 Science Place, Saskatoon, SK, Canada S7N 0X2. nixonj@agr.gc.ca
Heredity
|March 2, 2006
Summary
Assessing genetic data for segregation distortion is key for breeding strategies. A new single locus test is more powerful than the overall test for detecting selection effects in genetic linkage groups.
Area of Science:
- Quantitative genetics
- Statistical genetics
Background:
- Segregation distortion in genetic data can impact breeding strategies.
- Current methods using chi-squared tests at individual loci do not provide a holistic assessment of selection across a linkage group.
Purpose of the Study:
- To develop and compare statistical tests for assessing segregation distortion.
- To evaluate the power of these tests in detecting selection effects.
Main Methods:
- Developed a 'single locus test' based on the most significant P-value from locus-specific tests.
- Derived a new 'overall test' that incorporates genetic linkage within a single linkage group.
- Conducted simulations varying marker density and population size to compare test power.
Main Results:
- The single locus test demonstrated higher power in detecting selection at one or two loci compared to the overall test.
- The overall test accounts for genetic linkage but was less powerful.
- The single locus test requires more complex P-value corrections, for which approximate factors are provided.
Conclusions:
- The single locus test is a more powerful tool for detecting segregation distortion due to selection.
- Appropriate P-value corrections are necessary for the single locus test, with provided factors for different genetic marker densities and lengths.
Related Concept Videos
02:46Genetic Screens
Genetic screens are tools used to identify genes and mutations responsible for phenotypes of interest. Genetic screens help identify individuals or a group of people at risk of developing genetic diseases and help them with early intervention, targeted therapy, and reproductive options.
Forward genetic screens
Forward or “classical” genetic screens involve creating random mutations in an organism’s DNA using radiation, mutagens, or insertion of additional bases, which result in visible changes...
Forward genetic screens
Forward or “classical” genetic screens involve creating random mutations in an organism’s DNA using radiation, mutagens, or insertion of additional bases, which result in visible changes...
02:46Chi-square Analysis
The chi-square test is a statistical hypothesis test. It is used to check whether there is a significant difference between an expected value and an observed value. In the context of genetics, it enables us to either accept or reject a hypothesis, based on how much the observed values deviate from the expected values.
The chi-square test was developed by Pearson in 1990.
The first step of performing a Chi-square analysis is to establish a null hypothesis, which assumes that there is no real...
The chi-square test was developed by Pearson in 1990.
The first step of performing a Chi-square analysis is to establish a null hypothesis, which assumes that there is no real...
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.
01:18Dihybrid Crosses
Overview
02:45The Ratio of X Chromosome to Autosomes
In most organisms, sex is determined by the ratio of X and Y chromosomes. However, in some organisms, such as Drosophila and C.elegans, sex is determined by the ratio of the number of X chromosomes to the number of sets of autosomes. The Y chromosome in Drosophila is active but does not determine sex. It contains genes responsible for the production of sperms in adult flies.
Normal male Drosophila has a ratio of one X chromosome to two sets of autosomes. In contrast, normal female Drosophila...
Normal male Drosophila has a ratio of one X chromosome to two sets of autosomes. In contrast, normal female Drosophila...
02:27Trihybrid Crosses
Trihybrid Crosses
Some of Mendel’s crosses examined three pairs of contrasting characteristics. Such a cross is called a trihybrid cross. A trihybrid cross is a combination of three individual monohybrid crosses. For example, plant height (tall vs. short), seed shape (round vs. wrinkled), and seed color (yellow vs. green).
The F1 generation plants of a trihybrid cross are heterozygous for all three traits and produce eight gametes. Upon self-fertilization, these gametes have an equal chance to...
Some of Mendel’s crosses examined three pairs of contrasting characteristics. Such a cross is called a trihybrid cross. A trihybrid cross is a combination of three individual monohybrid crosses. For example, plant height (tall vs. short), seed shape (round vs. wrinkled), and seed color (yellow vs. green).
The F1 generation plants of a trihybrid cross are heterozygous for all three traits and produce eight gametes. Upon self-fertilization, these gametes have an equal chance to...