Protein sequence evidence for monophyly of the carnivore families Procyonidae and Mustelidae.

The amino acid sequence of the eye lens protein alpha-crystallin A of the ring-tailed cat, Bassariscus astutus, has been determined. The sequence of the Bassariscus alpha A chain, which is 173 residues long, was compared with the previously determined set of 41 mammalian alpha A sequences. Among the investigated carnivores (dog, cat, sloth bear, American mink, gray seal, and California sea lion) the Bassariscus alpha A sequence exclusively shares two amino acid replacements with the alpha A chain of the mink, Mustela vison: 7 His----Gln and 61 Ile----Val. The Mustela and Bassariscus alpha A sequences differ at only three positions and have no replacements in common with any of the other investigated carnivore alpha A chains. Furthermore, the replacement 7 His----Gln has only been found in three-toed sloth, whereas 61 Ile----Val occurs scattered in three other taxa: pig, rhinoceros, and prosimians. It thus is most parsimonious to join Bassariscus and Mustela--and consequently their respective families, Procyonidae and Mustelidae--as sister groups in the phylogenetic tree of mammalian alpha A sequences.