Low genetic variation. Genetic variation is the raw material of evolution. Without genetic variation, a population cannot evolve in response to changing environmental variables and, as a result, may face an increased risk of extinction.

Does evolution require genetic variation?

Genetic variation is an important force in evolution as it allows natural selection to increase or decrease frequency of alleles already in the population.

Can evolution occur without genetic alteration?

Whether that fitness is affected by genetic disorders, venomous saliva or enlarged offspring, heritable variation can only arise by mutation. Evolution is simply not possible without random genetic change for its raw material.