Mammalian evolution and the interphotoreceptor retinoid binding protein (IRBP) gene: Convincing evidence for several superordinal clades

Abstract

Phylogenetic relationships of 25 mammalian species representing 17 of the 18 eutherian orders were examined using DNA sequences from a 1.2-kb region of the 5' end of exon 1 of the single-copy nuclear gene known as interphotoreceptor retinoid binding protein (IRBP). A wide variety of methods of analysis of the DNA sequence, and of the translated products, all supported a five-order clade consisting of elephant shrew (Macroscelidea)/aardvark (Tubulidentata)/and the paenungulates (hyracoids, sirenians, and elephants), with bootstrap support in all cases of 100%. The Paenungulata was also strongly supported by these IRBP data. In the majority of analyses this monophyletic five-order grouping was the first branch off the tree after the Edentata. These results are highly congruent with two other recent sources of molecular data. Another superordinal grouping, with similar 100% bootstrap support in all of the same wide-ranging types of analyses, was Artiodactyla/Cetacea. Other superordinal affinities, suggested by the analyses, but with less convincing support, included a Perissodactyla/Artiodactyla/Cetacea clade, an Insectivora/Chiroptera clade, and Glires (an association of rodents and lagomorphs).

Endemic African mammals shake the phylogenetic tree

“…1a). In agreement with other molecular studies [7][8][9][10] that included an assortment of taxa, most interordinal associations are not resolved at bootstrap values Ͼ75%. However, the mtDNA data do provide strong support for the association of the two paenungulates (hyrax, manatee) together, and of these with elephant shrews, aardvarks and golden moles (Fig.…”

“…Anatomical data provide some evidence that aardvarks and/or elephant shrews may be related to paenungulates 17,18 but suggest other hypotheses as well: for example, six osteological features are putative synapomorphies uniting elephant shrews with lagomorphs and rodents 19 . All the available sequence data, including amino-acid sequences 13,14 , DNA sequences for three nuclear genes [8][9][10] , and the present mitochondrial genes, support an association of aardvarks and elephant shrews with paenungulates. What is most unexpected is that golden moles, a family of insectivores, are also part of this clade.…”

“…12S rRNA transversions accumulated linearly as far back as the eutherian-metatherian split 24 . Nine independent cladogenic events were selected based on 12S rRNA sequence availability and paleostratigraphic data 10,24,30 (for example, Rattus to Mus (14 Myr); Sus to Tayassu (45 Myr); ruminants to Cetacea (60 Myr); Erinaceus to Metatheria (130 Myr)). Relative rates were calculated in reference to xenarthrans.…”

“…King penguins are pelagic predators. To obtain food for their chicks, the parents forage at sea up to the subantarctic or polar frontal zones, 300-1,000 km away from their breeding colony 9,10 . They essentially rely on myctophid fish, of which most are captured in daytime at 150-300 m depths 11 .…”

Old World fruitbat phylogeny: Evidence for convergent evolution and an endemic African clade

“…Instead of deriving from independent lineages, as previously believed, Megaloglossus, Lissonycteris, and Epomophorus share a common ancestor that likely resided in Africa. Another example of an endemic African clade revealed by molecular data, albeit at a higher taxonomic level and deeper in the mammalian tree, is the association of proboscideans, sirenians, hyracoids, tubulidentates, macroscelideans, and chrysochlorids (26,33,34). In both cases, geographic distributions yield insights into phylogenetic relationships that did not emerge from morphological studies.…”