What is it called when a trait is controlled by more than two alleles?

Answer 1

Since only two alleles can be present in an individual at each gene locus the trait can be further controlled/modified at another gene locus. Polygenic traits can be controlled from as few as two to multiple sites.

A simple example is whether a horse is chestnut (red) or bay/black/brown (not red).

The red or not red color of a horse is controlled at the extension locus where E is not red and e is red.

Any horse that is ee at the extension site is red.

A horse that is Ee or EE at the extension site is not red and can be a number of basic colors depending on it's genetic make up at the Agouti site.

aa would produce a "true black" horse

Aa or AA a bay horse

Ata AtAt AtA will produce a dark bay or brown horse.

The genetics of the horse at the extension site completely masks the color expression at the Agouti site. This makes the extention site epistatic over the

agouti site. The Agouti site is hypostatic to the extension site.

Answer 2

Yes. Not all traits are Mendelian traits. For example, polygenic inheritance involves many pairs of alleles governing a trait.

Answer 3

multiple alleles

Answer 4

Incomplete dominance.

Answer 5

True