Phylogenetic Relationships of Platyhelminthes Based on 18S Ribosomal Gene Sequences

Campos, Andrés; Cummings, Michael P.; Reyes, José Luis; Laclette, Juan Pedro

doi:10.1006/mpev.1997.0483

Cited by 63 publications

(35 citation statements)

References 42 publications

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“…These included species that belong to the basal metazoan phyla Porifera, Placozoa, and Cnidaria. To minimize the effects of long branches, common to most bilaterians, we also selected several sequences representing Platyhelminthes and Mollusca, which have been previously shown to be relatively slow evolving (Aguinaldo et al, 1997;Campos et al, 1998). As outgroups to metazoan animals, we used sequences from two choanoflagellates and from the fungus Saccharomyces cerevisiae.…”

Section: Resultsmentioning

confidence: 99%

A Molecular Phylogenetic Framework for the Phylum Ctenophora Using 18S rRNA Genes

Podar

Haddock

Sogin

et al. 2001

Molecular Phylogenetics and Evolution

154

121

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Section: Resultsmentioning

confidence: 99%

A Molecular Phylogenetic Framework for the Phylum Ctenophora Using 18S rRNA Genes

Podar

Haddock

Sogin

et al. 2001

Molecular Phylogenetics and Evolution

154

121

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“…These animals, lacking a coelome, segmentation, elaborate organs, and an anus (in flatworms) were considered, in a gradist perspective, to be the most primitive bilaterians. However, they were brought, through rRNA, inside the lophotrochozo- ans (25)(26)(27)(28), with whom they share a spiral mode of cleavage and ciliated larval forms that may be considered as modified trochophores.…”

Section: The Demise Of Articulé S and The Birth Ofmentioning

confidence: 99%

The new animal phylogeny: Reliability and implications

Adoutte

Balavoine

Lartillot

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

465

275

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DNA sequence analysis dictates new interpretation of phylogenic trees. Taxa that were once thought to represent successive grades of complexity at the base of the metazoan tree are being displaced to much higher positions inside the tree. This leaves no evolutionary ''intermediates'' and forces us to rethink the genesis of bilaterian complexity.A deep reorganization of the metazoan phylogenetic tree is presently taking place as a result of the input of molecular data. Far from being an exercise confined to a small circle of aficionados, the changing views on the pattern of animal interrelationships has profound consequences for understanding the underlying processes of animal diversification. As has repeatedly been stressed, we shall never be able to reason on the evolution of development and the way it has shaped animal diversity unless we have a reliable history of the path taken by this diversification. Here, we highlight the salient recent results based on genetic data, especially the displacement of taxa long thought to represent successive grades of complexity at the base of the metazoan tree, to much higher positions inside the tree. This leaves us with no evolutionary ''intermediates'' and forces us to rethink the genesis of bilaterian complexity. The reappraisal of animal evolution rests on several congruent approaches ranging from primary gene sequence analysis to qualitative molecular signatures within appropriate genes. Each of them, however, has its methodological difficulties; we shall, therefore, also try to briefly pinpoint the issues of contention and discuss the strength of the present view.Preliminary Comments on the Reliability of Phylogenetic Trees. To an outsider, the field of phylogenetic reconstruction may appear to be full of controversies and uncertainties. There have been acrimonious debates over the best methodology to use for reconstruction (phenetics vs. cladistics) and over the relative merits of morphological vs. molecular data. Worst of all, contradictory trees have kept pouring in, often with insufficient critical assessment. Obviously, we cannot review the whole field here, but we wish to emphasize three points to justify our reasoned optimism and confidence in the recent molecular phylogenies.

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“…Several molecular analyses based on both 18S rDNA (Campos et al 1998, Jondelius 1998, Winnepenninckx et al 1998b, Giribet et al 2000 and elongation factor-1α amino acid sequences (Berney et al 2000) show that acoelans and mesozoans, respectively, belong into (or close to) the Rhabdito-phora. Giribet et al (2000) have analysed the same morphological dataset as Zrzavý et al (1998) together with 18S rDNA sequences of many triploblasts (excluding Mesozoa) with a similar conclusion: Acoela belong to the Rhabditophora while position of the Nemertodermatida is uncertain.…”

Section: Mesozoamentioning

confidence: 99%

“…The conflicting views concerning the phylogenetic position of the Acoela and especially Nemertodermatida (both groups sometimes grouped with[in] the Rhabditophora forming the latter group paraphyletic; see Campos et al 1998, Jondelius 1998, Littlewood et al 1999b, Giribet et al 2000 were discussed above. Nonetheless, the close relationships of all the rhabditophoran groups, Macrostomomorpha (=Haplopharyngida + Macrostomida), Polycladida, Lecithoepitheliata (=Gnosonesimidae + Prorhynchidae), and Neoophora s.…”

Section: Parasitic Flatworms: Neodermata Revertospermata Mediofusatamentioning

confidence: 99%

The interrelationships of metazoan parasites: a review of phylum- and higher-level hypotheses from recent morphological and molecular phylogenetic analyses

Zrzavý¹

2001

FOLIA PARASIT

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Abstract. Phylogeny of seven groups of metazoan parasitic groups is reviewed, based on both morphological and molecular data. The Myxozoa (=Malacosporea + Myxosporea) are most probably related to the egg-parasitic cnidarian Polypodium (Hydrozoa?: Polypodiozoa); the other phylogenetic hypotheses are discussed and the possible non-monophyly of the Cnidaria (with the Polypodiozoa-Myxozoa clade closest to the Triploblastica) is suggested. The Mesozoa is a monophyletic group, possibly closely related to the (monophyletic) Acoelomorpha; whether the Acoelomorpha and Mesozoa represent the basalmost triploblast clade(s) or a derived platyhelminth subclade may depend on rooting the tree of the Triploblastica. Position of the monophyletic Neodermata (=Trematoda + Cercomeromorpha) within the rhabditophoran flatworms is discussed, with two major alternative hypotheses about the neodermatan sister-group relationships (viz., the "neoophoran" and "revertospermatan"). The Myzostomida are not annelids but belong among the Platyzoa, possibly to the clade of animals with anterior sperm flagella (=Prosomastigozoa). The Acanthocephala represent derived syndermates ("rotifers"), possibly related to Seison (the name Pararotatoria comb. n. is proposed for Seisonida + Acanthocephala). The crustacean origin of the Pentastomida based on spermatological and molecular evidence (Pentastomida + Branchiura = Ichthyostraca) is confronted with palaeontological views favouring the pre-arthropod derivation of the pentastomids. Phylogenetic position of the nematodes within the Ecdysozoa and evolution of nematode parasitism are discussed, and the lack of relevant information about the enigmatic ectoproctan parasite Buddenbrockia is emphasised.At present, the metazoan relationships are becoming clearer as phylogenetic techniques are applied to morphological and molecular characters, the molecular data grow exponentially, and the "morphological" (i.e., non-sequence) information is refined by using ultrastructural and biochemical methods. In the present paper, recent contributions concerning the phylogenetic position of major parasitic animal groups are discussed. Seven taxa were selected: two "pseudo-protist" groups that evidently belong to the Metazoa and represent the most simplified multicellular animals (Myxozoa, Mesozoa), two traditional metazoan phyla that are now regarded as modified parasitic representatives of more comprehensive groups (Acanthocephala, Pentastomida), one parasitic "annelid" subgroup recently elevated to a phyletic level, unrelated to the Annelida (Myzostomida), and two major parasitic groups whose sister-group relationships and evolution of host-parasite relationships are recently becoming elucidated (Neodermata, Nematoida).This paper is about trees. It should be emphasised here that a tree (cladogram, maximum likelihood tree, distance tree) is not (or should not be) a graphical presentation of author's personal opinion about the course of evolution. The tree represents a series of hypotheses about the character homology (whet...

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Phylogenetic Relationships of Platyhelminthes Based on 18S Ribosomal Gene Sequences

Cited by 63 publications

References 42 publications

A Molecular Phylogenetic Framework for the Phylum Ctenophora Using 18S rRNA Genes

A Molecular Phylogenetic Framework for the Phylum Ctenophora Using 18S rRNA Genes

The new animal phylogeny: Reliability and implications

The interrelationships of metazoan parasites: a review of phylum- and higher-level hypotheses from recent morphological and molecular phylogenetic analyses

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