Final answer:
Autozygosity is the quantity defined as the probability that two alleles at a locus in an individual are identical by descent.
Step-by-step explanation:
The quantity defined as the probability that two alleles at a locus in an individual are identical by descent is called autozygosity.
In population genetics, autozygosity refers to the likelihood that an individual has inherited two identical alleles for a specific gene from a recent common ancestor. It measures the extent of homozygosity in a population.
For example, if an individual has inherited one allele for a gene from their father and the same allele from their mother, they would be homozygous for that gene, indicating autozygosity.