Canon offers a feature called "Exposure Safety Shift" in many of its models. It appears to allow the camera to automatically adjust the aperture or shutter speed to allow an improved exposure. Does Nikon offer a similar feature? The closest I can find is the auto-ISO feature that automatically shifts ISO as you adjust the aperture or shutter speed.
I'm unaware of any Nikon with a safety shift function.
Canon's safety shift only comes into play if a required exposure setting is unavailable... i.e. the Ap/ISO settings require a 1/8000 exposure but the camera is only capable of 1/4000. I personally don't really see the benefit...
Nikons have behavior that is somewhat similar. If using auto ISO, with min shutter speed and max ISO limits set, the camera will override the min SS setting once the max ISO setting is reached rather than letting the underexposure occur.