What is Inbreeding Depression ?

    Inbreeding depression refers to decrease in fitness and vigour due to inbreeding. The degree of inbreeding is measured by the inbreeding coefficient. The main differences between inbreeding and heterosis are as follows

1. Inbreeding results from matings between closely related individuals, whereas heterosis results from crossing between unrelated strains.

2. Inbreeding depression is the decline in fitness and vigour with decreased heterozygosity, whereas heterosis is the increase in fitness and vigour with increased heterozygosity.

3. Inbreeding depression results due to fixation of unfavourable recessive genes in F2, while in case of heterosis the unfavourable recessive genes of one line (parent) are covered by favourable dominant genes of other parent. The fixation of all favourable dominant genes in one homozygous line is impossible due to linkage between some unfavourable recessive and favourable dominant genes.