Relationship among coelacanths, lungfishes, and tetrapods: A phylogenetic analysis based on mitochondrial cytochrome oxidase I gene sequences

Abstract

To clarify the relationship among coelacanths, lungfishes, and tetrapods, the amino acid sequences deduced from the nucleotide sequences of mitochondrial cytochrome oxidase subunit I (COI) genes were compared. The phylogenetic tree of these animals, including the coelacanth Latimeria chalumnae and the lungfish Lepidosiren paradoxa, was inferred by several methods. These analyses consistently indicate a coelacanth/lungfish clade, to which little attention has been paid by previous authors with the exception of some morphologists. Overall evidence of other mitochondrial genes reported previously and the results of this study equally support the coelacanth/lungfish and lungfish/tetrapod clades, ruling out the coelacanth/tetrapod clade.

Australian lungfish neurohypophysial hormone genes encode vasotocin and [Phe 2 ]mesotocin precursors homologous to tetrapod-type precursors

“…Several hypotheses on the relationship among extant vertebrate groups have been proposed based on molecular and morphological data. Analyses of mitochondrial 12S rRNA and cytochrome b gene sequences suggested that the lungfish and tetrapods are included in the same clade (20). On the other hand, mitochondrial cytochrome oxidase I and 28S rRNA gene sequences support the hypothesis that lungfishes and coelacanths form a monophyletic group and are equally closely related to land vertebrates (20).…”

“…Analyses of mitochondrial 12S rRNA and cytochrome b gene sequences suggested that the lungfish and tetrapods are included in the same clade (20). On the other hand, mitochondrial cytochrome oxidase I and 28S rRNA gene sequences support the hypothesis that lungfishes and coelacanths form a monophyletic group and are equally closely related to land vertebrates (20). Amino acid sequences of growth hormone (21) and the glycoprotein hormone ␣-subunit (22) of lungfishes have high homology with those of tetrapods.…”

Nuclear protein-coding genes support lungfish and not the coelacanth as the closest living relatives of land vertebrates

“…The most recent paleontological evidence demonstrated that the lungfish represent an ancient lineage and that several of the features defining this group remained highly conserved throughout the entire evolutionary history of land vertebrates (10). The majority of palaeontological studies published during the last decade suggest that lungfish (Dipnoi) are the closest living relatives of the tetrapods or, alternatively, that coelacanths and lungfish form a monophyletic group that is equally closely related to the land vertebrates (11,12).A wealth of molecular phylogenetic studies addressed the tetrapod origin question, first based on mitochondrial DNA data by using partial gene sequences, single genes, or a few genes, and more recently, based on complete mitochondrial genomes (9,(13)(14)(15)(16)(17)(18). Most of these mitochondria-based molecular phylogenetic studies favored the lungfish as the closest living relatives of tetrapods.…”

“…A wealth of molecular phylogenetic studies addressed the tetrapod origin question, first based on mitochondrial DNA data by using partial gene sequences, single genes, or a few genes, and more recently, based on complete mitochondrial genomes (9,(13)(14)(15)(16)(17)(18). Most of these mitochondria-based molecular phylogenetic studies favored the lungfish as the closest living relatives of tetrapods.…”

Molecular Phylogenetic Information on the Identity of the Closest Living Relative(s) of Land Vertebrates

“…D) Neighbor-joining analysis of the complete mitochondrial 12S and 16S rRNA genes (Hedges et al 1993). E) Maximum likelihood analysis of the complete mitochondrial COI gene (at the amino acid level; Yokobori et al 1994). F) Maximum parsimony, neighbor-joining, and maximum likelihood analyses of the almost complete nuclear 28S rRNA gene (Zardoya and Meyer 1996c) problem.…”