Evidence on mammalian phylogeny from sequences of exon 28 of the von Willebrand factor gene.

Phylogenetic relationships among 27 extant mammalian species (representing 15 placental orders) were studied using sequences of exon 28 of the gene encoding von Willebrand Factor (vWF), a glycoprotein which functions in blood clotting. Analysis of sequences coding for vWF revealed evidence for several subordinal and superordinal groupings, but the earliest branching sequence of placental mammals was left largely unresolved. Strong support was found for a monophyletic clade consisting of elephants, sea cows, hyraxes, aardvarks, and elephant shrews. This systematic placement of the elephant shrews agrees strongly with two other molecular data sets (interphotoreceptor retinoid binding protein and alpha-lens crystallins) and is consistent with analysis of fossil elephant shrews recently discovered in north Africa. Evidence from vWF sequences agrees with a number of previous molecular and morphological studies in providing strong support for the monophyly of both bats and rodents. The orders Primates, Proboscidea, Carnivora, Perissodactyla, and Artiodactyla were represented by more than one species which joined in each case to form a monophyletic order.