1
|
Kolicka M, Dabert M, Olszanowski Z, Dabert J. Sweet or salty? The origin of freshwater gastrotrichs (Gastrotricha, Chaetonotida) revealed by molecular phylogenetic analysis. Cladistics 2021; 36:458-480. [PMID: 34618974 DOI: 10.1111/cla.12424] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/09/2020] [Indexed: 11/29/2022] Open
Abstract
Chaetonotidae is the most diverse and widely distributed family of the order Chaetonotida (Gastrotricha) and includes both marine and freshwater species. Although the family is regarded as a sister taxon to the exclusively marine Xenotrichulidae, the type of environment, marine or freshwater, where Chaetonotidae originated is still not known. Here, we reconstructed the phylogeny of the family based on molecular sequence data and mapped both morphological and ecological characters to determine the ancestral environment of the first members of the family. Our results revealed that the freshwater genus Bifidochaetus is the earliest branching lineage in the paraphyletic Chaetonotidae (encompassing Dasydytidae and Neogosseidae). Moreover, we reconstructed Lepidochaetus-Cephalionotus clade as a monophyletic sister group to the remaining chaetonotids, which supports Kisielewski's morphological based hypothesis concerning undifferentiated type of body scales as a most primary character in Chaetonotidae. We also found that reversals to marine habitats occurred independently in different Chaetonotidae lineages, thus marine species in the genera Heterolepidoderma, Halichaetonotus, Aspidiophorus and subgenera Chaetonotus (Schizochaetonotus) or Chaetonotus (Marinochaetus) should be assumed as having secondarily invaded the marine environment. Character mapping revealed a series of synapomorphies that define the clade that includes Chaetonotidae (with Dasydytidae and Neogosseidae), the most important of which may be those linked to reproduction.
Collapse
Affiliation(s)
- Małgorzata Kolicka
- Department of Animal Taxonomy and Ecology, Faculty of Biology, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 6, Poznań, 61-614, Poland
| | - Miroslawa Dabert
- Molecular Biology Techniques Laboratory, Faculty of Biology, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 6, Poznań, 61-614, Poland
| | - Ziemowit Olszanowski
- Department of Animal Taxonomy and Ecology, Faculty of Biology, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 6, Poznań, 61-614, Poland
| | - Jacek Dabert
- Department of Animal Morphology, Institute of Environmental Biology, Faculty of Biology, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 6, Poznań, 61-614, Poland
| |
Collapse
|
2
|
Balsamo M, Artois T, Smith JPS, Todaro MA, Guidi L, Leander BS, Van Steenkiste NWL. The curious and neglected soft-bodied meiofauna: Rouphozoa (Gastrotricha and Platyhelminthes). HYDROBIOLOGIA 2020; 847:2613-2644. [PMID: 33551466 PMCID: PMC7864459 DOI: 10.1007/s10750-020-04287-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 04/25/2020] [Accepted: 05/04/2020] [Indexed: 06/11/2023]
Abstract
Gastrotricha and Platyhelminthes form a clade called Rouphozoa. Representatives of both taxa are main components of meiofaunal communities, but their role in the trophic ecology of marine and freshwater communities is not sufficiently studied. Traditional collection methods for meiofauna are optimized for Ecdysozoa, and include the use of fixatives or flotation techniques that are unsuitable for the preservation and identification of soft-bodied meiofauna. As a result, rouphozoans are usually underestimated in conventional biodiversity surveys and ecological studies. Here, we give an updated outline of their diversity and taxonomy, with some phylogenetic considerations. We describe successfully tested techniques for their recovery and study, and emphasize current knowledge on the ecology, distribution and dispersal of freshwater gastrotrichs and microturbellarians. We also discuss the opportunities and pitfalls of (meta)barcoding studies as a means of overcoming the taxonomic impediment. Finally, we discuss the importance of rouphozoans in aquatic ecosystems and provide future research directions to fill in crucial gaps in the biology of these organisms needed for understanding their basic role in the ecology of benthos and their place in the trophic networks linking micro-, meio- and macrofauna of freshwater ecosystems.
Collapse
Affiliation(s)
- Maria Balsamo
- Department of Biomolecular Sciences, University of Urbino, Urbino, Italy
| | - Tom Artois
- Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium
| | | | - M Antonio Todaro
- Department of Life Sciences, University of Modena-Reggio Emilia, Modena, Italy
| | - Loretta Guidi
- Department of Biomolecular Sciences, University of Urbino, Urbino, Italy
| | - Brian S Leander
- Departments of Botany and Zoology, University of British Columbia, Vancouver, BC, Canada
| | | |
Collapse
|
3
|
Bekkouche N, Worsaae K. Neuromuscular study of early branching Diuronotus aspetos (Paucitubulatina) yields insights into the evolution of organs systems in Gastrotricha. ZOOLOGICAL LETTERS 2016; 2:21. [PMID: 27688902 PMCID: PMC5034412 DOI: 10.1186/s40851-016-0054-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 08/17/2016] [Indexed: 05/27/2023]
Abstract
BACKGROUND Diuronotus is one of the most recently described genera of Paucitubulatina, one of the three major clades in Gastrotricha. Its morphology suggests that Diuronotus is an early branch of Paucitubulatina, making it a key taxon for understanding the evolution of this morphologically understudied group. Here we test its phylogenetic position employing molecular data, and provide detailed descriptions of the muscular, nervous, and ciliary systems of Diuronotus aspetos, using immunohistochemistry and confocal laser scanning microscopy. RESULTS We confirm the proposed position of D. aspetos within Muselliferidae, and find this family to be the sister group to Xenotrichulidae. The muscular system, revealed by F-actin staining, shows a simple, but unique organization of the trunk musculature with a reduction to three pairs of longitudinal muscles and addition of up to five pairs of dorso-ventral muscles, versus the six longitudinal and two dorso-ventral pairs found in most Paucitubulatina. Using acetylated α-tubulin immunoreactivity, we describe the pharynx in detail, including new nervous structures, two pairs of sensory cilia, and a unique canal system. The central nervous system, as revealed by immunohistochemistry, shows the general pattern of Gastrotricha having a bilobed brain and a pair of ventro-longitudinal nerve cords. However, in addition are found an anterior nerve ring, several anterior longitudinal nerves, and four ventral commissures (pharyngeal, trunk, pre-anal, and terminal). Two pairs of protonephridia are documented, while other Paucitubulatina have one. Moreover, the precise arrangement of multiciliated cells is unraveled, yielding a pattern of possibly systematic importance. CONCLUSION Several neural structures of Diuronotus resemble those found in Xenotrichula (Xenotrichulidae) and may constitute new apomorphies of Paucitubulatina, or even Gastrotricha. In order to test these new evolutionary hypotheses, comparable morphological data from other understudied gastrotrich branches and a better resolution of the basal nodes of the gastrotrich phylogeny are warranted. Nonetheless, the present study offers new insights into the evolution of organ systems and systematic importance of so-far neglected characters in Gastrotricha.
Collapse
Affiliation(s)
- Nicolas Bekkouche
- Marine Biological Section, Department of Biology, University of Copenhagen, Universitetsparken 4, 2100 Copenhagen Ø, Denmark
| | - Katrine Worsaae
- Marine Biological Section, Department of Biology, University of Copenhagen, Universitetsparken 4, 2100 Copenhagen Ø, Denmark
| |
Collapse
|
4
|
The phylogeny, evolutionary developmental biology, and paleobiology of the Deuterostomia: 25 years of new techniques, new discoveries, and new ideas. ORG DIVERS EVOL 2016. [DOI: 10.1007/s13127-016-0270-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
5
|
Ou Q, Morris SC, Han J, Zhang Z, Liu J, Chen A, Zhang X, Shu D. Evidence for gill slits and a pharynx in Cambrian vetulicolians: implications for the early evolution of deuterostomes. BMC Biol 2012; 10:81. [PMID: 23031545 PMCID: PMC3517509 DOI: 10.1186/1741-7007-10-81] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Accepted: 10/02/2012] [Indexed: 12/19/2022] Open
Abstract
Background Vetulicolians are a group of Cambrian metazoans whose distinctive bodyplan continues to present a major phylogenetic challenge. Thus, we see vetulicolians assigned to groups as disparate as deuterostomes and ecdysozoans. This divergence of opinions revolves around a strikingly arthropod-like body, but one that also bears complex lateral structures on its anterior section interpreted as pharyngeal openings. Establishing the homology of these structures is central to resolving where vetulicolians sit in metazoan phylogeny. Results New material from the Chengjiang Lagerstätte helps to resolve this issue. Here, we demonstrate that these controversial structures comprise grooves with a series of openings. The latter are oval in shape and associated with a complex anatomy consistent with control of their opening and closure. Remains of what we interpret to be a musculature, combined with the capacity for the grooves to contract, indicate vetulicolians possessed a pumping mechanism that could process considerable volumes of seawater. Our observations suggest that food captured in the anterior cavity was transported to dorsal and ventral gutters, which then channeled material to the intestine. This arrangement appears to find no counterpart in any known fossil or extant arthropod (or any other ecdysozoan). Anterior lateral perforations, however, are diagnostic of deuterostomes. Conclusions If the evidence is against vetulicolians belonging to one or other group of ecdysozoan, then two phylogenetic options seem to remain. The first is that such features as vetulicolians possess are indicative of either a position among the bilaterians or deuterostomes but apart from the observation that they themselves form a distinctive and recognizable clade current evidence can permit no greater precision as to their phylogenetic placement. We argue that this is too pessimistic a view, and conclude that evidence points towards vetulicolians being members of the stem-group deuterostomes; a group best known as the chordates (amphioxus, tunicates, vertebrates), but also including the ambulacrarians (echinoderms, hemichordates), and xenoturbellids. If the latter, first they demonstrate that these members of the stem group show few similarities to the descendant crown group representatives. Second, of the key innovations that underpinned deuterostome success, the earliest and arguably most seminal was the evolution of openings that define the pharyngeal gill slits of hemichordates (and some extinct echinoderms) and chordates.
Collapse
Affiliation(s)
- Qiang Ou
- Early Life Evolution Laboratory, School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China.
| | | | | | | | | | | | | | | |
Collapse
|
6
|
Persson DK, Halberg KA, Jørgensen A, Møbjerg N, Kristensen RM. Neuroanatomy ofHalobiotus crispae(Eutardigrada: Hypsibiidae): Tardigrade brain structure supports the clade panarthropoda. J Morphol 2012; 273:1227-45. [DOI: 10.1002/jmor.20054] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 04/26/2012] [Accepted: 05/27/2012] [Indexed: 12/18/2022]
|
7
|
Todaro MA, Kånneby T, Dal Zotto M, Jondelius U. Phylogeny of Thaumastodermatidae (Gastrotricha: Macrodasyida) inferred from nuclear and mitochondrial sequence data. PLoS One 2011; 6:e17892. [PMID: 21455302 PMCID: PMC3063787 DOI: 10.1371/journal.pone.0017892] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 02/14/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Phylogenetic relationships within Gastrotricha are poorly known. Attempts to shed light on this subject using morphological traits have led to hypotheses lacking satisfactory statistical support; it seemed therefore that a different approach was needed. METHODOLOGY/PRINCIPAL FINDINGS In this paper we attempt to elucidate the relationships within the taxonomically vast family Thaumastodermatidae (Macrodasyida) using molecular sequence data. The study includes representatives of all the extant genera of the family and for the first time uses a multi-gene approach to infer evolutionary liaisons within Gastrotricha. The final data set comprises sequences of three genes (18S, 28S rDNA and COI mtDNA) from 41 species, including 29 thaumastodermatids, 11 non-thaumastodermatid macrodasyidans and a single chaetonotidan. Molecular data was analyzed as a combined set of 3 genes and as individual genes, using Bayesian and maximum likelihood approaches. Two different outgroups were used: Xenotrichula intermedia (Chaetonotida) and members of the putative basal Dactylopodola (Macrodasyida). Thaumastodermatidae and all other sampled macrodasyidan families were found monophyletic except for Cephalodasyidae. Within Thaumastodermatidae Diplodasyinae and Thaumastodermatinae are monophyletic and so are most genera. Oregodasys turns out to be the most basal group within Thaumastodermatinae in analyses of the concatenated data set as well as in analyses of the nuclear genes. Thaumastoderma appears as the sister taxon to the remaining species. Surprisingly, Tetranchyroderma is non-monophyletic in our analyses as one group of species clusters with Ptychostomella while another appears as the sister group of Pseudostomella. CONCLUSIONS/SIGNIFICANCE Results in general agree with the current classification; however, a revision of the more derived thaumastodermatid taxa seems necessary. We also found that the ostensible COI sequences from several species do not conform to the general invertebrate or any other published mitochondrial genetic code; they may be mitochondrially derived nuclear genes (numts), or one or more modifications of the mitochondrial genetic code within Gastrotricha.
Collapse
Affiliation(s)
- M Antonio Todaro
- Department of Biology, University of Modena and Reggio Emilia, Modena, Italy.
| | | | | | | |
Collapse
|
8
|
Rothe BH, Schmidt-Rhaesa A, Kieneke A. The nervous system of Neodasys chaetonotoideus (Gastrotricha: Neodasys) revealed by combining confocal laserscanning and transmission electron microscopy: evolutionary comparison of neuroanatomy within the Gastrotricha and basal Protostomia. ZOOMORPHOLOGY 2011. [DOI: 10.1007/s00435-011-0123-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
9
|
Kieneke A, Ahlrichs WH, Arbizu PM. Morphology and function of reproductive organs inNeodasys chaetonotoideus(Gastrotricha:Neodasys) with a phylogenetic assessment of the reproductive system in Gastrotricha. ZOOL SCR 2009. [DOI: 10.1111/j.1463-6409.2009.00388.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
10
|
|
11
|
|
12
|
Rothe BH, Schmidt-Rhaesa A. Architecture of the nervous system in two Dactylopodola species (Gastrotricha, Macrodasyida). ZOOMORPHOLOGY 2008. [DOI: 10.1007/s00435-008-0077-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
13
|
Kieneke A, Riemann O, Ahlrichs WH. Novel implications for the basal internal relationships of Gastrotricha revealed by an analysis of morphological characters. ZOOL SCR 2008. [DOI: 10.1111/j.1463-6409.2008.00334.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
14
|
|
15
|
LEASI FRANCESCA, TODARO MANTONIO. The muscular system of Musellifer delamarei (Renaud-Mornant, 1968) and other chaetonotidans with implications for the phylogeny and systematization of the Paucitubulatina (Gastrotricha). Biol J Linn Soc Lond 2008. [DOI: 10.1111/j.1095-8312.2008.00974.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
16
|
Kieneke A, Martínez Arbizu P, Riemann O. Body musculature of Stylochaeta scirtetica Brunson, 1950 and Dasydytes (Setodytes) tongiorgii (Balsamo, 1982) (Gastrotricha: Dasydytidae): A functional approach. ZOOL ANZ 2008. [DOI: 10.1016/j.jcz.2007.11.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
17
|
|
18
|
Kieneke A, Ahlrichs WH, Martínez Arbizu P, Bartolomaeus T. Ultrastructure of protonephridia in Xenotrichula carolinensis syltensis and Chaetonotus maximus (Gastrotricha: Chaetonotida): comparative evaluation of the gastrotrich excretory organs. ZOOMORPHOLOGY 2007. [DOI: 10.1007/s00435-007-0051-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
19
|
Hochberg R. Comparative immunohistochemistry of the cerebral ganglion in Gastrotricha: an analysis of FMRFamide-like immunoreactivity in Neodasys cirritus (Chaetonotida), Xenodasys riedli and Turbanella cf. hyalina (Macrodasyida). ZOOMORPHOLOGY 2007. [DOI: 10.1007/s00435-007-0044-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
20
|
Kieneke A, Arbizu PM, Ahlrichs WH. Ultrastructure of the protonephridial system in Neodasys chaetonotoideus (Gastrotricha: Chaetonotida) and in the ground pattern of Gastrotricha. J Morphol 2007; 268:602-13. [PMID: 17440954 DOI: 10.1002/jmor.10536] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The taxon Neodasys has a basal position within Gastrotricha. This makes it very interesting for phylogenetic considerations in this group. To complete the reconstruction of the nephridial system in the stem species of Gastrotricha started earlier, we have studied the whole protonephridial system of Neodasys chaetonotoideus by means of complete sets of ultrathin sections and TEM. In many characters, protonephridia of N. chaetonotoideus resemble those of macrodasyidan gastrotrich species. For example, each of the six protonephridia, arranged in three pairs, consists of three distinct cells that constitute the continuous protonephridial lumen. Especially, the terminal cell of the protonephridia of N. chaetonotoideus shows a striking pattern: The perforation of the filter region is a meandering cleft that is continuous with the seam of the enfolded lumen of that cell. With the results presented here and that of former TEM studies, we give a comprehensive idea of the excretory organs in the ground pattern of Gastrotricha. Moreover, we can elaborate on the hypothesized protonephridial system in the stem species of Bilateria. We suggest that a meandering filtration cleft is a feature of the ground pattern of the Bilateria.
Collapse
Affiliation(s)
- Alexander Kieneke
- Zoosystematik & Morphologie, Institut für Biologie und Umweltwissenschaften, Carl von Ossietzky Universität Oldenburg, 26111 Oldenburg, Germany.
| | | | | |
Collapse
|
21
|
Petrov NB, Pegova AN, Manylov OG, Vladychenskaya NS, Mugue NS, Aleshin VV. Molecular phylogeny of Gastrotricha on the basis of a comparison of the 18S rRNA genes: Rejection of the hypothesis of a relationship between Gastrotricha and Nematoda. Mol Biol 2007. [DOI: 10.1134/s0026893307030107] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
22
|
Leasi F, Rothe BH, Schmidt-Rhaesa A, Todaro MA. The musculature of three species of gastrotrichs surveyed with confocal laser scanning microscopy (CLSM). ACTA ZOOL-STOCKHOLM 2006. [DOI: 10.1111/j.1463-6395.2006.00230.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
23
|
Todaro MA, Telford MJ, Lockyer AE, Littlewood DTJ. Interrelationships of the Gastrotricha and their place among the Metazoa inferred from 18S rRNA genes. ZOOL SCR 2006. [DOI: 10.1111/j.1463-6409.2006.00228.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
24
|
Manylov OG, Vladychenskaya NS, Milyutina IA, Kedrova OS, Korokhov NP, Dvoryanchikov GA, Aleshin VV, Petrov NB. Analysis of 18S rRNA gene sequences suggests significant molecular differences between Macrodasyida and Chaetonotida (Gastrotricha). Mol Phylogenet Evol 2004; 30:850-4. [PMID: 15012964 DOI: 10.1016/s1055-7903(03)00251-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2003] [Revised: 06/02/2003] [Indexed: 10/27/2022]
Abstract
Partial 18S rRNA gene sequences of four macrodasyid and one chaetonotid gastrotrichs were obtained and compared with the available sequences of other gastrotrich species and representatives of various metazoan phyla. Contrary to the earlier molecular data, the gastrotrich sequences did not comprise a monophyletic group but formed two distinct clades, corresponding to the Macrodasyida and Chaetonotida, with the basal position occupied by the sequences of Tetranchyroderma sp. and Xenotrichula sp., respectively. Depending on the taxon sampling and methods of analysis, the two clades were separated by various combinations of clades Rotifera, Gnathostomulida, and Platyhelminthes, and never formed a clade with Nematoda. Thus, monophyly of the Gastrotricha is not confirmed by analysis of the presently available molecular data.
Collapse
Affiliation(s)
- Oleg G Manylov
- Department of Invertebrate Zoology, St. Petersburg State University, St. Petersburg 199034, Russia
| | | | | | | | | | | | | | | |
Collapse
|
25
|
|
26
|
Giribet G. Molecules, development and fossils in the study of metazoan evolution; Articulata versus Ecdysozoa revisited. ZOOLOGY 2003; 106:303-26. [PMID: 16351916 DOI: 10.1078/0944-2006-00131] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Two conflicting hypotheses of protostome relationships, Articulata and Ecdysozoa, are reviewed by evaluating the evidence in favor and against each one of them. Understanding early embryonic development and segmentation in non-arthropod non-annelid protostomes seems crucial to the debate. New ways of coding metazoan matrices, avoiding ground-patterns and higher taxa, and incorporating fossil evidence seems the best way to avoid circular debates. Molecular data served as the catalyzer for the Ecdysozoa hypothesis, although morphological support had been implicitly suggested. Most molecular analyses published so far have shown some support for Ecdysozoa, whereas none has ever supported Articulata. Here, new analyses of up to four nuclear loci, including 18S rRNA, myosin heavy chain II, histone H3 and elongation factor 1-alpha are conducted to test the molecular support for Ecdysozoa, and, at least under some parameter sets, most data sets show a clade formed by the molting animals. In contrast, support for Articulata is not found under any analytical conditions.
Collapse
Affiliation(s)
- Gonzalo Giribet
- Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.
| |
Collapse
|
27
|
Todaro MA, Littlewood DTJ, Balsamo M, Herniou EA, Cassanelli S, Manicardi G, Wirz A, Tongiorgi P. The Interrelationships of the Gastrotricha Using Nuclear Small rRNA Subunit Sequence Data, with an Interpretation Based on Morphology. ZOOL ANZ 2003. [DOI: 10.1078/0044-5231-00093] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
28
|
Hochberg R, Litvaitis M. The muscular system of Dactylopodola baltica
and other macrodasyidan gastrotrichs in a functional and phylogenetic perspective. ZOOL SCR 2002. [DOI: 10.1046/j.1463-6409.2001.00066.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
29
|
|
30
|
Abstract
A new hypothesis for the evolution of Bilateria is presented. It is based on a reinterpretation of the morphological characters shared by protostomes and deuterostomes, which, when taken together with developmental processes shared by the two lineages, lead to the inescapable conclusion that the last common ancestor of Bilateria was complex. It possessed a head, a segmented trunk, and a tail. The segmented trunk was further divided into two sections. A dorsal brain innervated one or more sensory cells, which included photoreceptors. "Appendages" or outgrowths were present. The bilaterian ancestor also possessed serially repeated "segments" that were expressed ontogenetically as blocks of mesoderm or somites with adjoining fields of ectoderm or neuroectoderm. It displayed serially repeated gonads (gonocoels), each with a gonoduct and gonopore to the exterior, and serially repeated "coeloms" with connections to both the gut and the exterior (gill slits and pores). Podocytes, some of which were serially repeated in the trunk, formed sites of ultrafiltration. In addition, the bilaterian ancestor had unsegmented coeloms and a contractile blood vessel or "heart" formed by coelomic myoepithelial cells. These cells and their underlying basement membrane confine the hemocoelic fluid, or blood, in the connective tissue compartment. A possible scenario to account for this particular suite of characters is one in which a colony of organisms with a cnidarian grade of organization became individuated into a new entity with a bilaterian grade of organization. The transformation postulated encompassed three major transitions in the evolution of animals. These transitions included the origins of Metazoa, Eumetazoa, and Bilateria and involved the successive development of poriferan, cnidarian, and bilaterian grades of organization. Two models are presented for the sponge-to-cnidarian transition. In both models the loss of a flow-through pattern of water circulation in poriferans and the establishment of a single opening and epithelia sensu stricto in cnidarians are considered crucial events. In the model offered for the cnidarian-to-bilaterian transition, the last common ancestor of Eumetazoa is considered to have had a colonial, cnidarian-grade of organization. The ancestral cnidarian body plan would have been similar to that exhibited by pennatulacean anthozoans. It is postulated that a colonial organization could have provided a preadaptive framework for the evolution of the complex and modularized body plan of the triploblastic ancestor of Bilateria. Thus, one can explore the possibility that problematica such as ctenophores, the Ediacaran biota, archaeocyaths, and Yunnanozoon reflect the fact that complexity originated early and involved the evolution of a macroscopic compartmented ancestor. Bilaterian complexity can be understood in terms of Beklemishev "cycles" of duplication and colony individuation. Two such cycles appear to have transpired in the early evolution of Metazoa. The first gave rise to a multicellular organism with a sponge grade of organization and the second to the modularized ancestor of Bilateria. The latter episode may have been favored by the ecological conditions in the late Proterozoic. Whatever its cause, the individuation of a cnidarian-grade colony furnishes a possible explanation for the rapid diversification of bilaterians in the late Vendian and Cambrian. The creation of a complex yet versatile prototype, which could be rapidly modified by selection into a profusion of body plans, is postulated to have affected the timing, mode, and extent of the "Cambrian explosion." During the radiations, selective loss or simplification may have been as creative a force as innovation. Finally, colony individuation may have been a unique historical event that imprinted the development of bilaterians as the zootype and phylotypic stage. (ABSTRACT TRUNCATED)
Collapse
Affiliation(s)
- R A Dewel
- Department of Biology, Appalachian State University, Boone, NC 28606, USA.
| |
Collapse
|
31
|
Wirz A, Pucciarelli S, Miceli C, Tongiorgi P, Balsamo M. Novelty in phylogeny of gastrotricha: evidence from 18S rRNA gene. Mol Phylogenet Evol 1999; 13:314-8. [PMID: 10603259 DOI: 10.1006/mpev.1999.0650] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Gastrotricha form a phylum which is crucial for defining the origin of pseudocoelomates, in that they share a number of characters with Rotifera and Nematoda but also with acoelomates, and even the evolutionary relationships within the phylum are anything but defined. For this reason the first extensive molecular data on Gastrotricha from the 18S rRNA sequences of both orders have been obtained and analyzed. Sequence analyses show that the phylum Gastrotricha is strictly monophyletic along an evolutionary line quite distinct from that of both Rotifera and Nematoda. A new view of the evolutionary history of the phylum Gastrotricha is put forward, in which Chaetonotida, and not Macrodasyida, are the most primitive forms of the group, contrary to the commonly held view. A polyphyletic origin of aschelminthes is supported, and the misleading term pseudocoelomates should be discarded.
Collapse
Affiliation(s)
- A Wirz
- Dipartimento di Biologia Animale, Università di Modena, via Università, 4, Modena, I-41100, Italy
| | | | | | | | | |
Collapse
|
32
|
Abstract
Traditionally, Panarthropoda (Euarthropoda, Onychophora, Tardigrada) are regarded as being closely related to Annelida in a taxon Articulata, but this is not supported by molecular analyses. Comparisons of gene sequences suggest that all molting taxa (Panarthropoda, Nematoda, Nematomorpha, Priapulida, Kinorhyncha, Loricifera) are related in a monophyletic taxon Ecdysozoa. An examination of the characters supporting Articulata reveals that only segmentation with a teloblastic segment formation and the existence of segmental coelomic cavities with nephridia support the Articulata, whereas all other characters are modified or reduced in the panarthropod lineage. Another set of characters is presented that supports the monophyly of Ecdysozoa: molting under influence of ecdysteroid hormones, loss of locomotory cilia, trilayered cuticle and the formation of the epicuticle from the tips of epidermal microvilli. Comparative morphology suggests Gastrotricha as the sister group of Ecdysozoa with the synapomorphies: triradiate muscular sucking pharynx and terminal mouth opening. Thus there are morphological characters that support Articulata, but molecular as well as morphological data advocate Ecdysozoa. Comparison of both hypotheses should prompt further thorough and targeted investigations. J. Morphol. 238:263-285, 1998. © 1998 Wiley-Liss, Inc.
Collapse
Affiliation(s)
- Andreas Schmidt-Rhaesa
- Fakultät für Biologie, University of Bielefeld, Bielefeld, Germany
- Department of Biological Sciences, University of South Florida, Tampa, Florida
| | | | - Christian Lemburg
- Institut für Zoologie und Anthropologie, University of Göttingen, Göttingen, Germany
| | - Ulrich Ehlers
- Institut für Zoologie und Anthropologie, University of Göttingen, Göttingen, Germany
| | - James R Garey
- Department of Biological Sciences, University of South Florida, Tampa, Florida
| |
Collapse
|
33
|
Schmidt-Rhaesa A, Bartolomaeus T, Lemburg C, Ehlers U, Garey JR. The position of the Arthropoda in the phylogenetic system. J Morphol 1998; 238:263-285. [DOI: 10.1002/(sici)1097-4687(199812)238:3<263::aid-jmor1>3.0.co;2-l] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
34
|
FREGNI ELENA. The spermatozoa of macrodasyid gastrotrichs: observations by scanning electron microscopy. INVERTEBR REPROD DEV 1998. [DOI: 10.1080/07924259.1998.9652348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
35
|
Eibye-Jacobsen J. Development, Ultrastructure and Function of the Pharynx ofHalobiotus crispaeKristensen, 1982 (Eutardigrada). ACTA ZOOL-STOCKHOLM 1997. [DOI: 10.1111/j.1463-6395.1997.tb01015.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
36
|
Neuhaus B, Kristensen RM, Peters W. Ultrastructure of the Cuticle of Loricifera and Demonstration of Chitin using Gold-Labelled Wheat Germ Agglutinin. ACTA ZOOL-STOCKHOLM 1997. [DOI: 10.1111/j.1463-6395.1997.tb01008.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
37
|
The spermatozoa of three species of Xenotrichulidae (Gastrotricha, Chaetonotida): the two ?d�nne Nebengeisseln? of spermatozoa in Heteroxenotrichula squamosa are peculiar para-acrosomal bodies. ZOOMORPHOLOGY 1995. [DOI: 10.1007/bf00403170] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
38
|
|
39
|
Joffe BI, Wikgren M. Immunocytochemical Distribution of 5-HT (Serotonin) in the Nervous System of the GastrotrichTurbanella cornuta. ACTA ZOOL-STOCKHOLM 1995. [DOI: 10.1111/j.1463-6395.1995.tb00976.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
40
|
Abstract
Spermatogenesis and spermiogenesis in Lepidodermella squammata are confined to the postparthenogenic phase of the life cycle and coincide with developmental changes in the bilateral female gonads. Male stages are bilateral but asynchronous, in the lateral abdomen anterior to the female gonads. Maximum observed sperm production is two packets per side, or 64 sperm. Sperm formation occurs more rapidly at 27 degrees C than at 20 degrees C (p less than 0.001), requiring as little as 1 day. Two spermatogonial mitotic divisions produce a clone of four primary spermatocytes connected by bridges (stage 1). Centrioles are absent. Development occurs within a cyst. Meiotic divisions produce 16 spermatids (stage 2), each containing a dense, elongate, tapered nucleus. Cytoplasmic membranes enclose one end of the nuclear rod, excluding all other organelles. Completion of this process results in stage 3, a packet of 16 sperm associated with one dense sphere, a modified 'residual body' containing cytoplasmic debris. The residual body then disappears, leaving the sperm packet of stage 4. Each mature sperm is a dense nuclear rod with surrounding membranes, lacking acrosome, mitochondrion, centrioles, and flagellum. Function of sperm has not been demonstrated. The spermatozoa are of a reduced type not previously described.
Collapse
|
41
|
Turbeville JM, Ruppert EE. Epidermal muscles and peristaltic burrowing in Carinoma tremaphoros (Nemertini): Correlates of effective burrowing without segmentation. ZOOMORPHOLOGY 1983. [DOI: 10.1007/bf00312241] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
42
|
Ruppert EE, Travis PB. Hemoglobin-containing cells ofNeodasys (Gastrotricha, Chaetonotida). I. Morphology and ultrastructure. J Morphol 1983; 175:57-64. [DOI: 10.1002/jmor.1051750106] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|