I think you want genetic drift. That is a random event, which is subtly different than a chance event, though a chance event, such as an unforeseen accident can be part of it.
Accidents always happen by chance, but to be random they happen in no set numerical order.
genetic drift
Adaptation.
genetic drift
The chance that a given event will occur, usually expressed between the number 0 (will not occur) and 1 (will occur) is called probability.
Probability is the mathematical chance that an event will occur.
It is called probability that an event might happen on a scale from 0 to 1
It is the last, longest and deciding moto of the event. It is called the main event for good reason, all of the preceding races are only for a chance to race in the "main".
Probability of success is a mathematical chance that an event will occur.
A radiation event. Called adaptive radiation.
It is an event that is certain.It is an event that is certain.It is an event that is certain.It is an event that is certain.
Because that comet, which sent many dinosaurs into extinction, caused the mammals to go through a large adaptive radiation event that allowed the vast variation in mammals we see today, especially the variations called apes.
Depends on the event.