The idea that many different species may have come form a single ancestor is called

I believe it may be evolution

I believe you are talking about evolution

Explanation:

When many species evolve from a single one it is usually referred to as evolution.

With the construction of a shopping center near the habitat of rabbits, there will be a significant decrease in the population because food resources and in general the ecological niche will be negatively influenced.

The carrying capacity in general is reduced because the maximum population size that the environment can support indefinitely in a given period is reduced as there is not enough availability of resources in the environment