Answer:
Nature selects for the best fit individual for a given environment. Individuals that do not fit will slowly die off and become extinct.
Step-by-step explanation:
If a given environment has better fitness for white rabbits than black rabbits, then the population of black rabbits will slowly dwindle to almost nothing. Why? B/c in this given scenario white rabbits are better bit so they survive more and their offspring survive more. Black rabbits are not fit so they will die and if they have a chance to give birth to offspring, the offspring are not fit for their environment so they will die. Eventually, there might not be any black rabbits to further the population. Here the natural selected for the white trait.
This is how natural selection can cause extinction. Those that are able to adapt or are better fit in an environment will survive and give birth to the next generation. Those that can't adapt or are not fit, will die off.