The situation in which one set of species makes an area suitable for species with different niche requirements and often less suitable for itself is called

Facilitation.

Explanation:

The ecological succession is the various changes of the species and its ecosystem over the passage of time. The primary and secondary succession are two main types of ecological succession.

The facilitation model of succession explains that the former species makes environment more suitable for the up coming species. The later species require different niche and the former species makes the environment less suitable for itself but facilitate the growth of the later species.

Thus, the answer is facilitation.

a. suckling by young

b. hypothalamus

c. dopamine

d. trh

e. anterior pituitary

f. mammary glands

g. milk production