Yes they are linked. The application ratio is variable and depends on the speed/how much brake lever pressure is applied.
If you apply the front brake at low speed it will only apply the rear brake. If you have the NAV 5 look at the Trip/Bike Info/Last Ride readout and it will probably tell you that the rear brake was applied more times than the front which is why the rear pads tend to wear out before the front pads.