1. Codominance : When both the genes of an allelomorphic pair express themselves equally in `F_(1)` hybrid, the dominance is called codominance.
2. Explanation of codominance with a suitable example:
(1) The inheritance of coat colour in cattle is the classic example of codominance.
(2) There are two types of coat colour in cattle, viz, red (skin with red hair ) and white (skin with white hair )
(3) When a red cattle (RR) is crossed with a white cattle (WW) , the `F_(1)` hybrids posses roam colour (RW) .
(4) Roans possess a mixture or red and white colour side by side. This shows that both red and white traite are expressed equally.
(5) Further when roans are interbred, red, roans , and white are
Produced in 1:2:1 ratio, which is evident from a cross given below :
Phenotypes = 1 Red, 2 Roans , 1 White
Phenotypic ratio `= 1 :2 : 1 `
Genotypic ratio `= 1 :2 :1 `
