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

When a population is small, the scope and number of variations is limited, and hence diversity and traits are reduced. The small numbers of surviving tigers a cause of worry because it would cause loss of genetic variability. A disease may wipe out the leftover poulation, if the entire poulation is susceptible to the disease. It can cause sudden extinction of the tigers and loss of their genes forever, adversely affecting the diversity of nature.