Genetic, behavioural and morphological divergence, or genetic drift.

Divergence is the growing apart of two lineages - lines of descent. Divergence may occur at the morphological, behavioural and developmental level, and will always occur at the genetic level, at least when two lineages are reproductively isolated from one another.

genetic divergence

It is called speciation.

All evolution that results in increasing genetic divergence between subpopulations may result in speciation. That includes convergent evolution: convergence occurs at the phenotypical level, not at the genetic level.