2.
In this experiment we limited the food supply available to the rabbit population. . The rabbits had varied teeth length; initially all rabbits had short-teeth, but a mutation in later generations introduced into the population rabbits with longer teeth. During the 4th generation there were roughly 4 times as many short-teeth rabbits than there were rabbits with long-teeth.

As food became a limiting factor, the rabbit population allegedly experienced natural selection. Though the population was originally predominantly short-teeth, long-teeth rabbits overtook the population. That is, by the 7th generation the predominance reversed, and there more than 4 times as many long-teeth rabbits than there short-teeth rabbits.

Much like in the former experiment, the empirical evidence corroborates the hypothesis; the proportion of teeth length changed in response to a selective force. Long-teeth rabbits were better adapted to the environment, and underwent positive selection.

3.
It seems likely that fur color and teeth size alike, were modeled after genes with two alleles. That said, the results of the experiments are in line with such a model – and showed change in trait/allelic frequencies due to selective forces – as one rabbit trait became more common on the expense of another, over time. Therefore it could be said that each rabbit population experienced natural selection, under the current definition.

No one individual rabbit changed color or grew longer teeth over time, but rather since one heritable trait had higher fitness, and provided better survivability and more progeny than the other - the higher fitness trait grew more common as more of its progeny survived and spread.

As far as the fur color, since apparently white color fur rabbits were more susceptible (to being devoured by wolves), they experienced a negative selection pressure, gave less progeny, and thus were less prominent in the final population.

In organisms that have sex, the inheritance of nuclear DNA biparent...