In molecular cloning experiments, it can be useful to introduce silent mutations into a gene of interest in order to create or remove recognition sites for restriction enzymes.
Although some minimal evolution would obviously have taken place in the meantime, this was essentially silent mutations and marginal adaptations to cooler habitat.
The genetic differences among divergent populations can involve silent mutations (that have no effect on the phenotype) or give rise to significant morphological and/or physiological changes.
In particular, silent mutations are not point accepted mutations, nor are mutations which are lethal or which are rejected by natural selection in other ways.