3. A species of rats live in a certain type of tree with the branches evenly spaced. Smaller rats could not reach from branch to branch and larger rats would break the branches and fall. Soon, all rats were just the right size for the tree branches. Analyze the given example and evaluate how variation, adaptation and natural selection are major components of evolution.

Dear student,
Please find below the answer:

Variation in the size of rats eventually got selected by nature according to the conditions available around them.
 
Natural selection is the process by which nature selects the individual which can survive in a particular kind of environment with best possible traits. Nature selects those individuals which have variations which makes them more fit than others for the given environment. 

In the above-given example, the rats evolved in a way that they were just the right size for the tree branches. They adapted in the best possible way and passed down these adapted traits to most of their progeny over time and got selected by nature. Hence, we can say that all the three phenomena- variation, adaptation and natural selection are major components of evolution in the given population of rats.

Hope this clears your doubt.
Regards.