Using amplified fragment length polymorphism (AFLP) to unravel species relationships and delimitations in Minthostachys (Labiatae)

Abstract

Minthostachys (Benth.) Spach (Labiatae) is a South American genus of aromatic shrubs frequently collected as a condiment, for the preparation of tea, or for medicinal purposes. Notoriously difficult species delimitation, conflicting taxonomic treatments of the past, and the lack of a revision with modern methods have hampered the understanding of this ecologically and economically interesting group. The amplified fragment length polymorphism (AFLP) study presented in this paper supplements field and morphological studies within the framework of a taxonomic and systematic revision. AFLP is found to be unsuitable for the reconstruction of the phylogeny of Minthostachys. Although, in some cases, morphologically well-defined species are also genetically distinct, extensive gene flow seems to occur between strikingly different species growing in the immediate vicinity and even between Minthostachys and Clinopodium (Xenopoma) vanum. Samples from the most complicated species, M. mollis, are genetically very heterogeneous and mostly fall into two clusters according to their geographical origin, exhibiting a high discrepancy with the pattern of morphological variation. © 2007 The Linnean Society of London.