Answer:
scientist can learn how the rat has evolved based on where they live. it also helps find what the common ancestor was and all the common traits they have, for example rats in Norway may be used to the cold. and the rats in africa need to adapt to the heat and the constant threat of them being eaten.
In this example of evolutionary development, we can see a selective advantage.
Developing of new characteristics, in this case, the spots on moth's wings is a part of the process of adaptation of organisms to their environment.
The new characteristics are acquired through mutations and natural selection filters the ones that are the most beneficial for the holder.
For example, a mutation which results in moths having shorter wings is disadvantageous, because it makes the individual who possesses it less likely to survive and reproduce.
On the other hand, developing of spots that resemble eyes can be advantageous, since it enables the holder of the trait to be more successful and more likely to leave offspring.