Severe flooding in an area caused a population of minnows to become split into two separate ponds. Prior to the separation, the
male minnows all had a moderate number of spots.
Following the separation, the first pond was filled with larger fish that fed on minnows, so male minnows with fewer spots were
better able to avoid detection by predators. The minnows in the second pond, however, had very few predators, and female
minnows in this pond preferred to mate with males that had the most spots.
After many generations, the two minnow populations evolved into different species and could no longer interbreed.
Fish Species
Original Species
ainal Species
New Species 1
New Species 2
Average # of Spots
four to six
zero to two
eight to ten
Which of the following best describes why the two minnow populations evolved into separate species?