How did the reign of Caesar serve as a transition between the Roman Republic and the Roman Empire?

Caesar exposed the weakness of the Roman Republic through his extremely developed military and organisational skills. He proved that the Roman republican senate was not capable of handling the empire's affairs through his demonstration of what Rome required to be a successful republican empire. According to Örjan Wikander[1], Caesar's short reign ended the republic.
---- [1] Örjan Wikander is a modern historian who published a brief landmark study in 1984, covering areas of Caesars reign.