Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics?

The small numbers of surviving tigers is a cause of worry from the point of view of genetics because there are negligible genetic variations if there is a small number of population. Due to this they are not well adapted in the rapid environmental changes which are not favourable for them. If these changes are not controlled, a time may come when lack of useful variations may result in extinction of tigers.