The interaction observed in this diagram is

Two closely related species competing for the same resources cannot coexist indefinitely and the competitively inferior will be eliminated eventually. This principle is known as:

. . . . . . $A$ . . . . . . is a potent force in organic evolution. Identify the $A$.

Which of the following is an example of predation?

Death of the host shall be disastrous to:

$A$ cuckoo laying eggs in the nest of other species of birds is an example of