Lethality and Interaction of Genes

Content
Lethality and Interaction of Genes
Lethality
Interaction of genes
Abbreviated genotypic ratio
Two gene pairs affecting same character
Epistasis
Complementary genes
Duplicate genes
Additional interactions involving two gene pairs
Interactions between more than two gene pairs
Modifiers, suppressors and pleiotropic genes
Meiotic drive, segregation distortion and selfish genes
Penetrance and expressivity

Mendel's experiments discussed in the previous topic suggested that perhaps each character is controlled by a single factor or a single gene. One may get an idea from such results that a particular character is associated with a particular gene. However, a gene does not carry a character, but controls a developmental process. It is through an influence on the development that the gene brings about the desired effect on phenotype. It has also been shown that a gene may sometimes interfere with the development and may cause the death of the individual. Similarly, it was also discovered that the genes are not necessarily separate elements producing individually distinct effects. They may interact and produce a phenotype which may be the result of interaction of these genes.