* Richard Dobbs left for personal reasons - spokeswoman

* Latest high-level exit under president Rodger Lawson

* Ned Johnson: a period of "constructive adjustment"

By Ross Kerber

BOSTON, Nov 10 (Reuters) - Fidelity Investments has lost another senior executive, the latest example of churn in the top ranks of the Boston mutual fund giant.

Richard Dobbs, who ran purchasing and certain India-based operations, left Fidelity in September, company spokeswoman Anne Crowley confirmed, citing "personal reasons."

The company said it will name a replacement for Dobbs, who joined Fidelity in 2008.

Leadership changes at Fidelity are closely watched because of uncertainty about the future of the company when its patriarch, 79-year-old chairman and chief executive Edward C. "Ned" Johnson III, eventually steps down.

Dobbs is another executive to last only a short while under Rodger Lawson, the outsider who replaced much of the senior leadership of the family-controlled business after he was named president in mid-2007.