When a single creature, or a whole species, changes in order to better fit their environment it is called

evolution

explanation:

when there's changes in the environment, the creatures have to adapt in order to be able to survive. this causes genetic mutations that will provide the creature with advantageous traits to make it more competitive. over time, these changes might so drastic, that the creature doesn't look anything like its ancestors. this changes in order to better fir the environment are called evolution.

the father in the first generation probably had the recessive colorblind trait in his x chromosome. if he and his wife both had the colorblind trait, even if she had 1 recessive and 1 dominant, then that trait would be passed on to their kids.

(since you didn't attach the family tree this is just an assumption)