Twо clоsely relаted pоpulаtions of squirrels become sepаrated after a large river permanently changes course. Thousands of generations later, the two populations can no longer produce fertile offspring. This is an example of speciation. In a different population of flowering plants, a chromosome mutation immediately prevents some individuals from successfully reproducing with the rest of the population, even though they continue living in the same location. This is an example of speciation. Both blanks are ONE word.