The phonology and morphosyntax of Breton mutation

I analyse of initial consonant mutation in a Breton dialect, with a focus on establishing the division of labour between phonology and morphology in the triggering of mutation and its phonological expression. I argue that different types of mutation have different status in the grammar: some are purely phonological, others involve subsegmental morphemes with a clear morphosyntactic rationale, and for some the phonological aspects are clear but the morphosyntactic motivation remains obscure. In addition, the differences among the types of mutation support a stratal model of morphology-phonology interactions.