Bertrand Serlet (pictured), Apple’s senior vice president of Mac Software Engineering, will leave the firm to focus more on science and less on products.

Serlet joined Apple in 1997 and has been involved in all areas of Mac OS X development. He is commonly referred to as the ‘Father of Mac OS X’.

Before joining Apple, Serlet spent four years at Xerox PARC, then joined Jobs' NeXT in 1989.

"I’ve worked with Steve for 22 years and have had an incredible time developing products at both NeXT and Apple, but at this point, I want to focus less on products and more on science,” said Serlet.

Craig Federighi, Apple’s vice president of Mac Software Engineering, will assume Serlet’s responsibilities and report directly to Steve Jobs.

Federighi is responsible for the development of Mac OS X and has been managing the Mac OS software engineering group for the past two years.

Serlet added, "Craig has done a great job managing the Mac OS team for the past two years, Lion is a great release and the transition should be seamless.”