Molecular evidence for multiple origins of Insectivora and for a new order of endemic African insectivore mammals

Abstract

The traditional views regarding the mammalian order Insectivora are that the group descended from a single common ancestor and that it is comprised of the following families: Soricidae (shrews), Tenrecidae (tenrecs), Solenodontidae (solenodons), Talpidae (moles), Erinaceidae (hedgehogs and gymnures), and Chrysochloridae (golden moles). Here we present a molecular analysis that includes representatives of all six families of insectivores, as well as 37 other taxa representing marsupials, monotremes, and all but two orders of placental mammals. These data come from complete sequences of the mitochondrial 12S rRNA, tRNA-Valine, and 16S rRNA genes (2.6 kb). A wide range of different methods of phylogenetic analysis groups the tenrecs and golden moles (both endemic to Africa) in an all-African superordinal clade comprised of elephants, sirenians, hyracoids, aardvark, and elephant shrews, to the exclusion of the other four remaining families of insectivores. Statistical analyses reject the idea of a monophyletic Insectivora as well as traditional concepts of the insectivore suborder Soricomorpha. These findings are supported by sequence analyses of several nuclear genes presented here: vWF, A2AB, and alpha-beta hemoglobin. These results require that the order Insectivora be partitioned and that the two African families (golden moles and tenrecs) be placed in a new order. The African superordinal clade now includes six orders of placental mammals.

Figure 1

Majority-rule neighbor joining bootstrap tree based on maximum likelihood distances of the 12S rRNA, tRNA-Valine, and 16S rRNA mitochondrial DNA sequences.

Figure 2

Maximum likelihood tree of the combined 12S rRNA, tRNA-Valine, 16S rRNA, vWF, and A2AB data set, with branches drawn proportional to amount of sequence change, and with maximum likelihood bootstrap values added; only those bootstrap figures in excess of 50% are indicated.

Figure 3

Strict consensus bootstrap tree of parsimony, transversion parsimony, neighbor joining (with ML distances), and maximum likelihood analyses (bootstrap figures listed from top to bottom respectively) of the 12S rRNA, tRNA-Valine, and 16S rRNA data set, rooted with armadillo.