Sex-influenced characteristics

These are genetically controlled characters that may appear in organisms of both sexes but are expressed to a different degree in each sex. They are also called sex- controlled characters. Although they may even have identical genotypes in both males and female, they become more noticeable in one sex and almost lost in the other sex. For example, in human beings mammary glands enlarge and become functional only in female. Likewise, other organisms have some characters that mostly develop in one sex and do not develop in another. For instance, the comb and colourful plumage of a cock, the tail feathers in peacock, the horns in male sheep (ram) and the mane in lions as shown in Figure 2.36.

Figure 2.36: A picture showing female and male lion