Specialists occupy narrow ecological niches, using a restricted range of resources, environmental conditions, hosts, or habitats. Their morphology, physiology, or behavior may be highly efficient within that limited domain—for example, an insect dependent on one host plant or a predator adapted to a particular prey type. This specialization can reduce competition and improve performance when the focal resource is reliable. It also creates vulnerability: habitat alteration, climate shifts, disease of the host, or loss of a key resource leaves few alternatives. Generalists, by contrast, tolerate
Ref:
Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 13