sentence: Cheetahs have very little variation.
sentences_before: Infections and extreme climate events are frequent causes. Occasionally, invasions by more competitive species can be devastating. The extinction of many Australian marsupials by foreign species is a famous example. Although the population has rebounded, its genetic variability is much less than that of the Southern elephant seal.
sentences_after: We think the species was reduced to a small number at some recent time. Because it lacks genetic variation, it is in danger from infectious diseases.
concept_name: cheetah
headings: Genetic drift
categories: Evolutionary biology Classical genetics