The thirteen “D-genome” cotton species are a monophyletic assemblage of morphologically diverse diploids that inhabit arid to semi-arid regions in Mexico, with one disjunct species each in Peru and the Galapagos Islands, and one species whose range extends northward into Arizona. While these species lack significant fiber (i.e., cotton), they are important in that they represent one of the parental genomes of the cultivated tetraploid cottons. To assess phylogenetic relationships among these species we sequenced and analyzed a region of a nuclear-encoded alcohol dehydrogenase gene (AdhA). The results indicated that there have been lineage-specific gene duplications and variation in the rates of sequence evolution. Evidence for lineage sorting was obtained, as some sequence polymorphisms transcend species boundaries. The resulting topology was generally consistent with current taxonomic alignment of the species, although the phylogeny based on AdhA sequences conflicts with those inferred from cpDNA and ITS data sets, most notably in the position of the anomalous species G. gossypioides.

Key words: Adh, Gossypium, Malvaceae, phylogeny