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Philos Trans R Soc Lond B Biol Sci. 1998 Jul 29; 353(1372): 1221–1237.
PMCID: PMC1692306

The platypus is not a rodent: DNA hybridization, amniote phylogeny and the palimpsest theory.


We present DNA-hybridization data on 21 amniotes and two anurans showing that discrimination is obtained among most of these at the class and lower levels. Trees generated from these data largely agree with conventional views, for example in not associating birds and mammals. However, the sister relationships found here of the monotremes to marsupials, and of turtles to the alligator, are surprising results which are nonetheless consistent with the results of some other studies. The Marsupionta hypothesis of Gregory is reviewed, as are opinions about the placement of chelonians. Anatomical and reproductive data considered by Gregory do not unequivocally preclude a marsupial-monotreme special relationship, and there is other recent evidence for placing turtles within the Diapsida. We conclude that the evidential meaning of the molecular data is as shown in the trees, but that the topologies may be influenced by a base-compositional bias producing a seemingly slow evolutionary rate in monotremes, or by algorithmic artefacts (in the case of turtles as well).

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Selected References

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  • Archer CB, Wells RS, MacDonald DM. Metastatic cutaneous carcinoid. J Am Acad Dermatol. 1985 Aug;13(2 Pt 2):363–366. [PubMed]
  • Arnason U, Gullberg A, Janke A. Phylogenetic analyses of mitochondrial DNA suggest a sister group relationship between Xenarthra (Edentata) and Ferungulates. Mol Biol Evol. 1997 Jul;14(7):762–768. [PubMed]
  • Benton MJ. Phylogeny of the major tetrapod groups: morphological data and divergence dates. J Mol Evol. 1990 May;30(5):409–424. [PubMed]
  • Blackburn DG, Vitt LJ, Beuchat CA. Eutherian-like reproductive specializations in a viviparous reptile. Proc Natl Acad Sci U S A. 1984 Aug;81(15):4860–4863. [PMC free article] [PubMed]
  • Cavalli-Sforza LL, Edwards AW. Phylogenetic analysis. Models and estimation procedures. Am J Hum Genet. 1967 May;19(3 Pt 1):233–257. [PMC free article] [PubMed]
  • Clark CT, Smith KK. Cranial osteogenesis in Monodelphis domestica (Didelphidae) and Macropus eugenii (Macropodidae). J Morphol. 1993 Feb;215(2):119–149. [PubMed]
  • D'Erchia AM, Gissi C, Pesole G, Saccone C, Arnason U. The guinea-pig is not a rodent. Nature. 1996 Jun 13;381(6583):597–600. [PubMed]
  • Eernisse DJ, Kluge AG. Taxonomic congruence versus total evidence, and amniote phylogeny inferred from fossils, molecules, and morphology. Mol Biol Evol. 1993 Nov;10(6):1170–1195. [PubMed]
  • Graur D, Hide WA, Li WH. Is the guinea-pig a rodent? Nature. 1991 Jun 20;351(6328):649–652. [PubMed]
  • Hedges SB. Molecular evidence for the origin of birds. Proc Natl Acad Sci U S A. 1994 Mar 29;91(7):2621–2624. [PMC free article] [PubMed]
  • Hedges SB, Moberg KD, Maxson LR. Tetrapod phylogeny inferred from 18S and 28S ribosomal RNA sequences and a review of the evidence for amniote relationships. Mol Biol Evol. 1990 Nov;7(6):607–633. [PubMed]
  • Hu Y, Wang Y, Luo Z, Li C. A new symmetrodont mammal from China and its implications for mammalian evolution. Nature. 1997 Nov 13;390(6656):137–142. [PubMed]
  • Hutcheon JM, Kirsch JA, Pettigrew JD. Base-compositional biases and the bat problem. III. The questions of microchiropteran monophyly. Philos Trans R Soc Lond B Biol Sci. 1998 Apr 29;353(1368):607–617. [PMC free article] [PubMed]
  • Janke A, Arnason U. The complete mitochondrial genome of Alligator mississippiensis and the separation between recent archosauria (birds and crocodiles). Mol Biol Evol. 1997 Dec;14(12):1266–1272. [PubMed]
  • Janke A, Xu X, Arnason U. The complete mitochondrial genome of the wallaroo (Macropus robustus) and the phylogenetic relationship among Monotremata, Marsupialia, and Eutheria. Proc Natl Acad Sci U S A. 1997 Feb 18;94(4):1276–1281. [PMC free article] [PubMed]
  • Jenkins FA, Jr, Gatesy SM, Shubin NH, Amaral WW. Haramiyids and Triassic mammalian evolution. Nature. 1997 Feb 20;385(6618):715–718. [PubMed]
  • Kirsch JA, Pettigrew JD. Base-compositional biases and the bat problem. II. DNA-hybridization trees based on AT- and GC-enriched tracers. Philos Trans R Soc Lond B Biol Sci. 1998 Mar 29;353(1367):381–388. [PMC free article] [PubMed]
  • Kirsch JA, Springer MS, Krajewski C, Archer M, Aplin K, Dickerman AW. DNA/DNA hybridization studies of the carnivorous marsupials. I: The intergeneric relationships of bandicoots (Marsupialia: Perameloidea). J Mol Evol. 1990 May;30(5):434–448. [PubMed]
  • Klima M. Early development of the shoulder girdle and sternum in marsupials (Mammalia: Metatheria). Adv Anat Embryol Cell Biol. 1987;109:1–91. [PubMed]
  • Kumazawa Y, Nishida M. Variations in mitochondrial tRNA gene organization of reptiles as phylogenetic markers. Mol Biol Evol. 1995 Sep;12(5):759–772. [PubMed]
  • Lapointe FJ, Kirsch JA, Bleiweiss R. Jackknifing of weighted trees: validation of phylogenies reconstructed from distance matrices. Mol Phylogenet Evol. 1994 Sep;3(3):256–267. [PubMed]
  • Loomis WF, Smith DW. Molecular phylogeny of Dictyostelium discoideum by protein sequence comparison. Proc Natl Acad Sci U S A. 1990 Dec;87(23):9093–9097. [PMC free article] [PubMed]
  • Mannen H, Tsoi SC, Krushkal JS, Li WH, Li SS. The cDNA cloning and molecular evolution of reptile and pigeon lactate dehydrogenase isozymes. Mol Biol Evol. 1997 Nov;14(11):1081–1087. [PubMed]
  • Page RD. TreeView: an application to display phylogenetic trees on personal computers. Comput Appl Biosci. 1996 Aug;12(4):357–358. [PubMed]
  • Pettigrew JD. Genomic evolution. Flying DNA. Curr Biol. 1994 Mar 1;4(3):277–280. [PubMed]
  • Pettigrew JD, Kirsch AW. Base-compositional biases and the bat problem. I. DNA-hybridization melting curves based on AT- and GC-enriched tracers. Philos Trans R Soc Lond B Biol Sci. 1998 Mar 29;353(1367):369–379. [PMC free article] [PubMed]
  • Porter CA, Goodman M, Stanhope MJ. Evidence on mammalian phylogeny from sequences of exon 28 of the von Willebrand factor gene. Mol Phylogenet Evol. 1996 Feb;5(1):89–101. [PubMed]
  • Sabeur G, Macaya G, Kadi F, Bernardi G. The isochore patterns of mammalian genomes and their phylogenetic implications. J Mol Evol. 1993 Aug;37(2):93–108. [PubMed]
  • Seutin G, Lang BF, Mindell DP, Morais R. Evolution of the WANCY region in amniote mitochondrial DNA. Mol Biol Evol. 1994 May;11(3):329–340. [PubMed]
  • Sharman GB. Reproductive physiology of marsupials. Science. 1970 Feb 27;167(3922):1221–1228. [PubMed]
  • Sheldon FH, Bledsoe AH. Indexes to the reassociation and stability of solution DNA hybrids. J Mol Evol. 1989 Oct;29(4):328–343. [PubMed]
  • Smith KK. Development of craniofacial musculature in Monodelphis domestica (Marsupialia, Didelphidae). J Morphol. 1994 Nov;222(2):149–173. [PubMed]

Articles from Philosophical Transactions of the Royal Society B: Biological Sciences are provided here courtesy of The Royal Society


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