Multiple loci Flashcards
Continuous traits are polygenic. What does this mean?
Multiple loci are involved.
For polygenic traits, the effects of all the alleles are additive. True or false?
True.
For polygenic traits, the alleles can vary in fitness. True or false?
True.
Define an epistatic allele.
One that prevents expression of a different allele at another locus.
Are all polygenic interaction additive?
No, epistasis is not.
Say an organisms possesses an advantageous allele but it is not expressed. Why might this be?
It is masked by an epistatic allele.
Epistasis only reduces fitness by masking other alleles. True or false?
False - epistasis can also increase fitness by masking deleterious alleles.
There are 2 categories of epistasis. What are they?
- Magnitude
2. Sign
What are the 2 types of magnitude epistasis?
- Synergistic
2. Antagonistic
Define synergistic epistasis.
A double-mutant results in a larger mutational effect than expected.
What kind of effect does synergistic epistasis have on beneficial mutations?
There are even greater improvements to function.
What kind of effect does synergistic epistasis have on deleterious mutations?
It protects against the negative effects, creating a less severe drop in fitness.
What kind of effect does antagonistic epistasis have on beneficial mutations?
There is a reduction in expected fitness.
What kind of effect does antagonistic epistasis have on deleterious mutations?
It causes a greater than expected fitness drop.
Define sign epistasis.
The mutation has the opposite effect than expected when in the presence of another mutation.
