Changes (6)
There are a few possibilities for this:
fluctuations
'changes' is the definition.
(adapting is a kind of changing)
This is the entire clue.
(Other definitions for adapts that I've seen before include "Becomes adjusted to new conditions" , "Changes to suit new circumstances" , "Adjusts for a new use" , "Change to fit new circumstances" , "Modifies for a new use" .)
'changes' is the definition.
('alter' can be a synonym of 'change')
This is all the clue.
(Other definitions for alters that I've seen before include "Changes to staler state" , "Changes, modifies" , "Changes, makes different" .)
'changes' is the definition.
(fluctuation is a kind of change)
This is all the clue.