Examples of Polygenic Inheritance
Polygenic inheritance in humans
In humans, there are so many examples of polygenic inheritance. Like skin or hair color, height, and eye pigmentation.
Skin Pigmentation in Human
Skin color is controlled by three pairs of genes, Aa, Bb, and Cc, located in different chromosomes. A very dark person will have all six dominant genes (AA, BB, and CC). A person with very light skin color has all the six recessive genes (aa, bb, cc). Suppose a man with a homozygous condition for dark skin (AABBCC) marries a woman who is homozygous for light skin color (Aabbcc), their progeny in the F1 generation will have an intermediate color (AaBbCc) in the skin that differs from that of both parents. This is called mulatto color.
The crossing between two F1 individuals results in a highly variable F2 progeny in which a few individuals resemble one grandparent, a few resemble the other grandparent, and the remaining range between the two. The skin color ranges from pure black (AABBCC) in 1/64 individuals very dark brown in 6/64 individuals, dark brown in 15/64 individuals, mulatto (or intermediate) (AaBbCc) in 20/64 individuals, light brown in 15/64 individuals, very light brown in 6/64 individuals and pure white (aabbcc) in 1/64 individuals.
What is Polygenic Inheritance?
Polygenic inheritance is a type of inheritance in which multiple genes control the phenotype of an organism. The phenotypes or traits can be height, skin color, the color of the eyes, etc. This type of inheritance is also known as quantitative inheritance or multifactorial inheritance. Such traits are known as polygenic traits. It is different from mendelian genetic inheritance in a number of genes controlling the traits. Polygenic inheritance can be seen in animals as well as plants. Every gene that controls traits is not necessarily equal. However, environmental factors also play an important role in polygenic inheritance. Polygenic inheritance has important implications for our understanding of complex diseases and traits, as well as for conservation and agricultural breeding.