how can the lack in genetic variation affect the survival of a ...

[Sandstorm]

i just need a little help with my bio homework.

[TI]

Less genetic material available from which to develop mutations that would allow adaptation to changing conditions.
Also, too much risk for detrimental recessive traits to be prevalent in specific genes.

[federox]

Genetic variation throughout the course of evolution provides changes and adaptations to the surviving organisms so as to deal with changing climatic, environmental, or any other conditions.
Lack of this variation can adversely affect survival of species, they might die out completely by not having what it takes to survive.
Genetic variation serves as the raw material when it comes to studying evolution. With no variations at all, the concept of evolution doesn't remain the same.