(2) The different genetic combinations in a gene pool.
The importance of genetic diversity is evident in terms of survival and adaptability of a species. For instance, a species with high genetic diversity will tend to produce a wider variety of offspring, where some of them may become the most fit variants.
In contrast, a species that has little or no genetic diversity will produce offspring that are genetically alike and therefore will likely be susceptible to diseases or problems similar to those of their parent.
Hence, little or lack of genetic diversity reduces biological fitness and increases the chances of species extinction.
Compare: genetic variability.