Heterozygosity | Animal Husbandry & Veterinary Science Optional for UPSC PDF Download

Definition of Heterozygosity

Heterozygosity arises from outcrossing and crossbreeding, contrasting with inbreeding. Inbreeding tends to increase the number of homozygous gene pairs, while outcrossing and crossbreeding increase heterozygosity when parents have different alleles.

For instance, if Breed I is homozygous dominant and Breed II is homozygous recessive for a specific gene pair, their offspring will be heterozygous.

Maximum Heterozygosity:

• In the F1 generation of breeds and lines with homozygosity for different alleles, maximum heterozygosity is achieved. However, heterozygosity decreases in subsequent generations due to gene segregation.

Heterozygosity Variability:

• When multiple gene pairs influence a trait, varying levels of heterozygosity are observed. This leads to differences in heterozygosity among animals for specific traits.

Transmission of Genes

Outbred or crossbred animals are less likely to breed true compared to inbred animals due to heterozygosity. For example, a genotype AABBCCDD will transmit all genes uniformly, while AaBbCcDd can produce diverse gene combinations.

Uniformity in Traits

Groups of outcross or crossbred animals in the F1 generation are likely to exhibit uniform traits related to physical fitness, especially when parents are homozygous in opposite ways for specific alleles.