Yes, there is. The mother of this litter has produced more offspring than can survive. That is called, overproduction.
What are they doing?
Because there are so many of them, there is not enough resources, such as food, water, and a place to live, for all the rabbits to survive. So as they are all trying to survive, they are competing for these resources to survive.
They all look so different! Like you and me are different!
You're right! We are all different. These differences are called variations. Variations can be described as differences in size, coloration, etc.
Most of the rabbits look like their mother. Why is it that some of them don't?
Most offspring of a species will have the same traits as the mother, but some will inherit a different genetic trait that will help them survive in their environment.
So, if only most of the rabbits have the necessary qualities to survive, what will happen to the rest?
Well, harsh to say, but the rabbits who don't have what they need to survive will die off and the rest will thrive and reproduce and this cycle called natural selection will start over again.
Wow! We sure learned a lot about natural selection!