A variety of circumstances will affect the growth and decline of a population of, say, insects in a particular environment: reproductive rates, available food supply, populations of predators, etc.
(A variety of circumstances; will affect; the growth and decline of a population of, say, insects in a particular environment: reproductive rates, available food supply, populations of predators, etc.)
A variety of circumstances
will affect
the growth and decline of a population of, say, insects in a particular environment: reproductive rates, available food supply, populations of predators, etc.