Kupriyanova NS and Ryskov AP
Molecular phylogeny of the reptiles does not accept the basal split of squamates into Iguania and Scleroglossa that is in conflict with morphological evidence. The classical phylogeny of living reptiles places turtles at the base of the tree. Analyses of mitochondrial DNA and nuclear genes join crocodilians with turtles and places squamates at the base of the tree. Alignment of the reptiles’ ITS2s with the ITS2 of chordates has shown a high extent of their similarity in ancient conservative regions with Cephalochordate Branchiostoma floridae, and a less extent of similarity with two Tunicata, Saussurea tunicate, and Rinodina tunicate. We have performed also an alignment of ITS2 segments between the two break points coming into play in 5.8S rRNA maturation of Branchiostoma floridae in pairs with orthologs from different vertebrates where it was possible. A similarity for most taxons fluctuates between about 50 and 70%. This molecular analysis coupled with analysis of phylogenetic trees constructed on a basis of manual alignment, allows us to hypothesize that primitive chordates being the nearest relatives of simplest vertebrates represent the real base of the vertebrate phylogenetic tree.
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