DJs Colin Murray and Edith Bowman are to end their three-year Radio 1 partnership as part of an overhaul of the station's schedules.
The pair once worked together on Channel 4's Rise breakfast show
Bowman will now host their 1300 to 1600 weekday slot alone, while Murray is to present a show offering new music from Mondays to Thursdays at 2200.
New shows focusing on particular music genres and presented by experts are to run at 2100 on those four nights.
Most of the schedule changes are due to come into effect on 25 September.
Murray said: "I'm grateful to be given the chance to front a show that really hits those turned-on, engaged evening Radio 1 listeners."
The programme would be "exciting and personal and it's going to show a blatant disregard for musical pigeon-holing", he said.
Bowman, whose Radio 1 partnership with Murray began with the Saturday breakfast show in 2003, said: "I'll miss our daily banter but I'm on cloud nine at what lies ahead and the incredible opportunity I've been given."
Her afternoon show would be an "evolution of the present one", she added.
Other changes include:
- New signings Eddie Halliwell and Trophy Twins to present club music shows
- Chris Coco and Fergie to leave the station, though Fergie to continue to put together Essential Mixes
- A 1Xtra showcase to highlight the best new black music
- Specialist music output to increase by four hours a week overall
Station controller Andy Parfitt said the changes to specialist programming would offer a "broader range of content".
"We believe that this and the amazing talent line-up will help even more listeners to come and sample the wealth of distinctive specialist shows Radio 1 has to offer."