If only one species is considered the 'fittest', why do we still have so many variation among species?

your answer is "the 1950's"

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.

genetic variation will increase because of a new habitat and food source.

explanation:

you should wear a lead protective shield when having teeth x-rays

hope i

-lavira : )