specialist

Someone who is an expert in, or devoted to, some specific branch of study or research.

A physician whose practice is limited to a particular branch of medicine or surgery.

Any of several non-commissioned ranks corresponding to that of corporal.

An organism that is specialized for a particular environment.

“The tree Lepidothamnus laxifolius is a high alpine specialist found in high-altitude bog communities and in scrub.”

Specialised.