Epenthesis, mutation, and structure preservation in the Shona causative

In Shona (Bantu: Zimbabwe), the causative fonn of a verb is fonned in one of two ways: either with the suffix -is-/-es- or by changing the root final consonant to a corresponding coronal continuant. The author argues for an analysis in which both fonns are derived from a common underlying suffix /sl. The suffixal fonn is the result of an independently motivated process of epenthesis. The mutation, on the other hand, comes about by fusion of the /s/ with the preceding consonant. This fusion leads in some cases to feature combinations disallowed in Shona. The effects of mutation in these cases can be captured exploiting an active version of Kiparsky's Structure Preservation in tenns of "persistent rules".