Skin colour, resulting from several genes, is said to be polygenic.
Structural variation is obvious in domestic animals that have been bred
for particular traits
A population is said to be polymorphic for a trait if there are several
variants for that particular trait for example the coat colour of tabby
cats, human blood groups. If the population is identical for a particular
trait, that is no variations for that trait, it is said to be monomorphic
[1] for that trait. If the characteristic is controlled by one gene it is
said to be monogenic, [2] if the result of several genes, for example,
human skin colour, then it is polygenic. [3] Variation in chromosome number
within a species also contributes to variations, for example, polyploidy in
thorn apples gives rise to differences in fruit shape and texture between
members of the same species.
