Stability of cladistic relationships between Cetacea and higher-level Artiodactyl taxa

Over the Fast 10 years, the phylogenetic relationships among higher-level a rtiodactyl taxa hale been examined with multiple data sets. Many of these d ata sets suggest that Artiodactyla (even-toed ungulates) is paraphyletic an d that Cetacea (whales) represents a highly derived "artiodactyl" subgroup. Ln this report, phylogenetic relationships between Cetacea and artiodactyl s are tested with a combination of 15 published data sets plus new DNA sequ ence data from two nuclear loci, interphotoreceptor retinoid-binding protei n (IRBP) and von Willebrand factor (vWF). The addition of the IRBP and vWF character sets disrupts none of the relationships supported by recent cladi stic analyses of the other 15 data sets. Simultaneous analyses support thre e critical clades: (Cetacea + Hiopopotamidae), (Cetacea + Hippopotamidae Ruminantia), and (Cetacea + Hippopotamidae + Ruminantia + Suina). Perturbat ions of the combined matrix show that the above clades are stable to a vari ety of disturbances. A chronicle of phylogenetic results over the past 3 ye ars suggests that cladistic relationships between Cetacea. and artiodactyls have been stal le to increased taxonomic sampling and to the addition of m ore than 1,400 informative characters from 15 data sets.