Terminology

Genetic diversity is the variety of alleles and genotypes present in the group under study (population, species or group of species).

The genetic composition of a population is usually described in terms of allele frequencies, number of alleles and heterozygosity

Polymorphic -The presence in a species of two or more alleles at a locus, e.g. A1 and A2.
Polymorphic loci are usually defined as having the most frequent allele at a frequency of less
than 0.99, or less than 0.95 (to minimize problems with different sample sizes).

Monomorphic -A locus in a population is monomorphic if it has only one allele present, e.g. A1.
All individuals are homozygous for the same allele. Lacking genetic diversity.