Answer:
Competitive exclusion
Step-by-step explanation:
Competitive exclusion is a concept that explains the process that occurs when two closely related species population coexist or occupy the same ecological niche. The two species share and compete the for same resources under the same condition.
Along the line, one species with the greatest fitness outcompetes the other, thereby leading to the outnumbering if the other species.
The population of the fittest increase, while the others population begin to decline.
This concept of competitive exclusion is what the graph above exemplifies.