Single-gene and Polygenic Traits By: Kyra GREEN
Single-gene Traits
A single-gene trait is a trait that is controlled by only one gene. For instance, if long hair on guinea pigs was dominant, then short hair would be recessive; and the guinea pig would either just have long or short hair.
The long hair on the black and white guinea pig would be dominant over the short hair.
Freckles and no Freckles are single-gene traits
Someone can either have a widows peak or not; making it a single-gene trait.
This is the kind of chart you would see for a Single-gene trait.
Polygenic Traits
Polygenic traits are traits that are controlled by two or more genes.
Because of the many different genes, there are many different alleles. This then creates many different types of genotypes and phenotypes.
Different eye colors are polygenic because they can vary depending on their parents.
Height is also polygenic because not everyone is either tall or short; there can many different medium heights.
This is what a normal polygenic chart would look like if you had many different types of alleles.
This Curved chart is also another example of polygenic traits; also using skin color. The highest points show the average skin color, and the lower points are less common skin colors.