Heterozygosity is a measure of genetic variation within a population and refers to individuals that carry two different alleles at a given locus (Leroy et al. 2018). Loss of heterozygosity is a driver of genetic erosion and is linked to genetic drift and inbreeding (Leroy et al. 2018, Gaggiotti et al. 2018). There is a direct relationship between heterozygosity and Effective population size (Wang et al. 2016). Reduced heterozygosity (i.e. genetic variation) can lead to reduced fitness and loss of adaptive potential (Leroy et al. 2018).
As with calculation of Effective population size and Allelic diversity, estimation requires the collection and analysis of genetic data that requires a high level of technical expertise.
Calculation of heterozygosity requires a high marker density (markers across multiple loci, to give an overall assessment of heterozygosity within an individual’s genome) but can be assessed with a low sample size (<100 individuals within a population sampled e.g. DNA extracted from blood or animal/plant tissue) (Leroy et al. 2018).
Metrics include:
The desired heterozygosity will be species/project specific. Generally, a higher level of heterozygosity is better.