In a population of short, ground-dwelling animals, some offspring were produced that were approximately 1 cm taller than others in the population. this group was able to reach slightly higher vegetation than the rest of the population. when these animals grew up, they were able to produce more offspring than other animals in the population. this pattern, where the tallest animals were more likely to survive and reproduce, continued over several generations. eventually, after many generations, all members of the population were at least 20 cm taller than animals of the original population had been. what does this illustrate?