DOCSLIB.ORG

Evolutionary Relationship of Porifera Within the Eukaryotes

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Evolutionary Relationship of Porifera Within the Eukaryotes Hydrobiologia (2006) 568(S):167–176 Ó Springer 2006 G. Coulter, O. Timoshkin, L. Timoshkina & K. Martens (eds), Species and Speciation in Ancient Lakes DOI 10.1007/s10750-006-0318-6 Evolutionary relationship of Porifera within the eukaryotes Werner E.G. Mu¨ ller*, Isabel M. Mu¨ ller & Heinz C. Schro¨ der Institut fu¨r Physiologische Chemie, Abteilung Angewandte Molekularbiologie, Universita¨t, Duesbergweg 6, 55099 , Mainz, Germany (*Author for correspondence: E-mail: [email protected]; Tel: +6131-3925910; Fax: +6131-3925243) Key words: phylogeny, COI, Metazoa Abstract Molecular data, gathered in our laboratory, strongly support the view that all metazoan phyla, including Porifera, are of monophyletic origin. More recently, a hypothetical common ancestor for all Metazoa, the Urmetazoa, had be formulated. The Urmetazoa possessed besides the key structures of an extracellular matrix also immune molecules and signal transduction molecules that are characteristic to Metazoa. In addition, we could establish that all Metazoa share a common ancestry with the Fungi and Plantae, while the unicellular eukaryotes are only distantly related. With respect to the origin of freshwater sponges, especially the species found in the Lake Baikal as a representative for an ‘‘old’’ lake, have been investigated. Sequence comparisons were performed with the ubiquitously distributed freshwater sponge Spongilla la- custris (family Spongillidae) as well as with one marine sponge, Suberites domuncula. The sequence com- parison of the mitochondrial COI gene revealed a monophyletic grouping of the endemic baikalian sponges with S. lacustris as the most related species to the common ancestor. The sequences from Baikalospongia recta, B. intermedia, B. bacillifera and Lubomirskia baicalensis were found to be identical and separated from that of Swartschewskia lacustris and S. papyracea. In a further approach the exon/intron sequences framing the intron-2 of the sponge tubulin gene were chosen for the phylogenetic analysis. Data analyses revealed again a monophyletic grouping with S. lacustris as the closest related species to the common ancestor. It is concluded that the baikalian sponges, which have been studied here, are of monophyletic origin. Furthermore, the data suggest that the endemic species S. papyracea is the phylogenetic oldest still extant endemic baikalian sponge species. Introduction mate receptor (Perovic et al., 1999), as well as (iii) homologs/modules of an primordial immune sys- With the introduction of molecular data based on tem, e.g. immunoglobulin-like molecules (Scha¨ cke analyses of nucleotide [nt] sequences, coding for et al., 1994a), SRCR- and SCR-repeats (Pancer proteins, it became evident that the phylum Porif- et al., 1997b) or the Rhesus system (Seack et al., era (sponges) is with the other metazoan phyla of 1997), and (iv) cell surface receptor molecules, e.g. monophyletic origin. The molecules which most receptor tyrosine kinases (Scha¨ cke et al., 1994b). strongly suggest that Porifera have to be included The cDNAs have been isolated – and some of them in the Metazoa are those which are constituent also expressed – from all classes of Porifera, mainly elements (i) of the basal lamina, e.g. integrin from the Demospongiae Geodia cydonium and receptor (Pancer et al., 1997a), fibronection (Pahler Suberites domuncula, but also from Calcarea, Sy- et al., 1998) and polypeptides, rich in scavenger con raphanus and from Hexactinellida, Rhabdoca- SRCR and SCR modules (Pahler et al., 1998), (ii) lyptus dawsoni. Based on these molecular data it is of neuronal transmission, e.g. metabotropic gluta- reasonable to the accept that multicellular animals 168 evolved only once (monophyly), as first published the position of sponges. Amino acid [aa] sequences in 1994 (Mu¨ ller et al., 1994) and later in detail found in all representatives of these subkingdoms, (Mu¨ ller, 1995, 1998). This conclusion drawn from one heat shock protein, the serine/threonine (Ser/ analyses of protein-coding nt sequences has been Thr) kinase domain of protein kinases, b-tubulin recently supported also by rRNA ribosomal data and calmodulin were analyzed together with those (Cavalier-Smith et al., 1996). deduced from sponge cDNAs. Unlike with Metazoa the monophyletic origin First, polypeptides grouped to the heat shock of Plantae appears to be established since a longer proteins [HSP] of the 70-kDa class, the HSP70, time; they can be traced back to the Chlorophyta were investigated. Heat shock proteins are highly (reviewed in: Margulis & Schwartz, 1995). The conserved throughout living kingdoms. These ancestry of the third group of multicellular molecules act as molecular chaperones under eukaryotes, the Fungi, is less clear; monophyletic physiological and stress conditions; the chaper- and polyphyletic evolution of these spore forming ones of prokaryotic organisms, which are related and amastigote organisms are discussed (in Mar- to the eukaryotic HSP70 multigene family are gulis & Schwartz, 1995). termed DnaK. They are divided according to We addressed for the first time the phylogenetic their different inducibility into (i) the group of relationship of the three multicellular eukaryotic constitutively expressed heat shock proteins, subkingdoms to unicellular eukaryotes, putting the which are also present under nonstressed condi- main emphasis on the position of sponges. Deduced tions, and (ii) the group of HSP70 polypeptides, amino acid [aa] sequences of cDNAs from sponges which are induced under temperature shock and coding for proteins, found in all representatives of other specific stress situations. The inducible, these subkingdoms have been analyzed. The data cytoplasmic HSP70 amino acid (aa) sequences presented (Schu¨ tze et al., 1999) show that the were selected for the analysis (Koziol et al., 1996, sponge molecules, especially those obtained from 1998). the classes Demospongiae and Calcarea form the Second, the serine/threonine (Ser/Thr) kinase basis of the metazoan branch. Furthermore, the domain found in protein kinases from Fungi and results reveal that the Metazoa appeared later dur- Metazoa, but not in Plantae or unicellular ing evolution from the unicellular eukaryotes than eukaryotes (Hardie & Hanks, 1995; Kruse et al., the Fungi and the Plantae (Viridiplantae). 1997) was used for the analyses. These enzymes are Focusing on freshwater sponges a similar clar- essential for fungal or metazoan organisms to ification of the evolutionary relationship remains recognize extracellular signals and to initiate to be determined. An interesting, approach to intracellularly appropriate adaptive biological solve the evolutionary origin of the freshwater responses. sponges are studies on endemic freshwater sponges Third, sequences of b-tubulin, one major ele- especially from geologically old biotopes. Lake ment of microtubuli (intracellular structures that Baikal is famous because of its high biodiversity, are employed for a number of functions in especially with respect to its freshwater sponges eukaryotes, including flagellar motility and chro- (Rezvoi, 1936). This lake is the oldest (>24 mil- mosome aggregation as well as cell maintenance of lion years), deepest (1637 m) and most volumi- cellular morphology) were analyzed (Schu¨ tze nous lake on earth, comprising one fifth of the et al., 1999). world’s unfrozen freshwater; it contains more than Finally, calmodulin, a protein ubiquitous in 1500 endemic species (Stewart, 1990). eukaryotes, was selected for phylogenetic analysis. It is a Ca2+ binding protein of approximately 150 aa residues that is involved in a wide range of Phylogenetic position of sponges: the Urmetazoa intracellular signaling pathways. The molecule binds four Ca2+ ions in a cooperative fashion The aim of a previous study (Schu¨ tze et al., 1999) during which it undergoes a conformational was the evaluation of the phylogenetic relationship change. The calmodulin sequence from G. cydo- of the three multicellular eukaryotic subkingdoms nium was identified for the purpose of the phylo- to unicellular eukaryotes, with the main interest in genetic analysis (Schu¨ tze et al., 1999). 169 The data on b-tubulin are summarized. Metazoa has been termed Urmetazoa (Mu¨ ller, Homology searches of the sponge deduced aa b- 2001). The major novelties, which can be attrib- tubulin sequence TBB_GEOCY revealed highest uted to the Urmetazoa, have been summarized similarity to the sequence from Caenorhabditis (Mu¨ ller, 2001). elegans (96% similar aa). Phylogenetic analysis was performed which showed that the b-tubulin molecules from Metazoa are more closely related to the tubulin sequences from Fungi or Plantae The phylogenetic position of the three sponge classes than to unicellular eukaryotes (Schu¨ tze et al., 1999); Figure 1. The rooted tree strikingly shows Until our studies the phylogenetic position of the that the sponge sequence forms with the other class Hexactinellida within the phylum Porifera metazoan molecules one branch (Fig. 1). The ro- [sponges] could not be resolved by molecular data, bust grouping separates the Metazoa from the because no cDNA encoding a protein from the Viridiplantae, the Fungi and the unicellular sponge class Hexactinellida was available. We eukaryotes. As an outgroup for this analysis the have isolated and characterized the cDNA bacterial cell-division protein FtsZ was used. encoding a protein kinase C belonging to the C In conclusion, phylogenetic analyses of the four subfamily (cPKC) from the hexactinellid sponge deduced
Load more

Recommended publications
  • Animal Phylum Poster Porifera
    Phylum PORIFERA CNIDARIA PLATYHELMINTHES ANNELIDA MOLLUSCA ECHINODERMATA ARTHROPODA CHORDATA Hexactinellida -- glass (siliceous) Anthozoa -- corals and sea Turbellaria -- free-living or symbiotic Polychaetes -- segmented Gastopods -- snails and slugs Asteroidea -- starfish Trilobitomorpha -- tribolites (extinct) Urochordata -- tunicates Groups sponges anemones flatworms (Dugusia) bristleworms Bivalves -- clams, scallops, mussels Echinoidea -- sea urchins, sand Chelicerata Cephalochordata -- lancelets (organisms studied in detail in Demospongia -- spongin or Hydrazoa -- hydras, some corals Trematoda -- flukes (parasitic) Oligochaetes -- earthworms (Lumbricus) Cephalopods -- squid, octopus, dollars Arachnida -- spiders, scorpions Mixini -- hagfish siliceous sponges Xiphosura -- horseshoe crabs Bio1AL are underlined) Cubozoa -- box jellyfish, sea wasps Cestoda -- tapeworms (parasitic) Hirudinea -- leeches nautilus Holothuroidea -- sea cucumbers Petromyzontida -- lamprey Mandibulata Calcarea -- calcareous sponges Scyphozoa -- jellyfish, sea nettles Monogenea -- parasitic flatworms Polyplacophora -- chitons Ophiuroidea -- brittle stars Chondrichtyes -- sharks, skates Crustacea -- crustaceans (shrimp, crayfish Scleropongiae -- coralline or Crinoidea -- sea lily, feather stars Actinipterygia -- ray-finned fish tropical reef sponges Hexapoda -- insects (cockroach, fruit fly) Sarcopterygia -- lobed-finned fish Myriapoda Amphibia (frog, newt) Chilopoda -- centipedes Diplopoda -- millipedes Reptilia (snake, turtle) Aves (chicken, hummingbird) Mammalia
    [Show full text]
  • BIOSC 041 Overview of Animal Diversity: Animal Body Plans
    BIOSC 041 Overview of Animal Diversity: Animal Body Plans Reference: Chapter 32 Outline v Definition and major characteristics of animals v Dividing animals into groups based on: § Body symmetry § Tissues § Type of body cavity § Protostome vs deuterostome development v Animal Phylogeny What is an Animal? v Scientists have identified 1.3 million living species of animals v The definition of an animal § Multicellular § Heterotrophic eukaryotes § Possess tissues that develop from embryonic layers v Common characteristics describe the group 1. Common mode of nutrition 2. Cell structure and specialization 3. Reproduction and development 1. Characteristics of Animals: Nutrition v Animals are heterotrophs (“other-eater”) § Obtain nutrition either from other living organisms or from nonliving organic material § Primary consumers (herbivores), secondary consumers (eat herbivores), tertiary consumers (eat carnivores), and/or detritovores (eat detritus- decaying plants/ animals, feces) 2. Characteristics of Animals: Cell Structure and Specialization 1. Animals are multicellular eukaryotes (Note: single-celled eukaryotes with animal-like behavior are grouped as Protists, such as amoeba) 2. Animal cells lack cell walls 3. Bodies are held together by structural proteins like collagen 4. Bodies are organized into tissues, organs, and organ systems § Tissues are groups of cells that have a common structure, and/or function § Nervous tissue and muscle tissue are unique to animals Amoeba: a protist, not a true animal 3. Characteristics of Animals: Reproduction and Development v Most animals reproduce sexually, with the diploid stage dominating the life cycle v Development occurs in specific stages 1. Fertilization to form zygote 2. Zygote undergoes rapid cell division called cleavage 3. Cleavage leads to formation of a multicellular, hollow blastula (ex: whitefish blastula slides from lab, with cells undergoing rapid mitosis) 4.
    [Show full text]
  • Analysis of the Complete Mitochondrial DNA Sequence of the Brachiopod Terebratulina Retusa Places Brachiopoda Within the Protostomes
    See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/12415870 Analysis of the complete mitochondrial DNA sequence of the brachiopod Terebratulina retusa places Brachiopoda within the protostomes Article in Proceedings of the Royal Society B: Biological Sciences · November 1999 DOI: 10.1098/rspb.1999.0885 · Source: PubMed CITATIONS READS 83 50 2 authors, including: Martin Schlegel University of Leipzig 151 PUBLICATIONS 2,931 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Rare for a reason? Scale-dependence of factors influencing rarity and diversity of xylobiont beetles View project Bat diversity and vertical niche activity in the fluvial flood forest Leipzig View project All content following this page was uploaded by Martin Schlegel on 22 May 2014. The user has requested enhancement of the downloaded file. Analysis of the complete mitochondrial DNA sequence of the brachiopod Terebratulina retusa places Brachiopoda within the protostomes Alexandra Stechmann* and Martin Schlegel UniversitÌt Leipzig, Institut fÏr Zoologie/Spezielle Zoologie,Talstr. 33, 04103 Leipzig, Germany Brachiopod phylogeny is still a controversial subject. Analyses using nuclear 18SrRNA and mitochondrial 12SrDNA sequences place them within the protostomes but some recent interpretations of morphological data support a relationship with deuterostomes. In order to investigate brachiopod a¤nities within the metazoa further,we compared the gene arrangement on the brachiopod mitochondrial genome with several metazoan taxa. The complete (15 451bp) mitochondrial DNA (mtDNA) sequence of the articulate brachiopod Terebratulina retusa was determined from two overlapping long polymerase chain reaction products. All the genes are encoded on the same strand and gene order comparisons showed that only one major rearrangement is required to interconvert the T.retusa and Katharina tunicata (Mollusca: Polyplaco- phora) mitochondrial genomes.
    [Show full text]
  • Tropical Marine Invertebrates CAS BI 569 Phylum ANNELIDA by J
    Tropical Marine Invertebrates CAS BI 569 Phylum ANNELIDA by J. R. Finnerty Phylum ANNELIDA Porifera Ctenophora Cnidaria Deuterostomia Ecdysozoa Lophotrochozoa Chordata Arthropoda Annelida Hemichordata Onychophora Mollusca Echinodermata Nematoda Platyhelminthes Acoelomorpha Silicispongiae Calcispongia PROTOSTOMIA “BILATERIA” (=TRIPLOBLASTICA) Bilateral symmetry (?) Mesoderm (triploblasty) Phylum ANNELIDA Porifera Ctenophora Cnidaria Deuterostomia Ecdysozoa Lophotrochozoa Chordata Arthropoda Annelida Hemichordata Onychophora Mollusca Echinodermata Nematoda Platyhelminthes Acoelomorpha Silicispongiae Calcispongia PROTOSTOMIA “COELOMATA” True coelom Coelomata gut cavity endoderm mesoderm coelom ectoderm [note: dorso-ventral inversion] Phylum ANNELIDA Porifera Ctenophora Cnidaria Deuterostomia Ecdysozoa Lophotrochozoa Chordata Arthropoda Annelida Hemichordata Onychophora Mollusca Echinodermata Nematoda Platyhelminthes Acoelomorpha Silicispongiae Calcispongia PROTOSTOMIA PROTOSTOMIA “first mouth” blastopore contributes to mouth ventral nerve cord The Blastopore ! Forms during gastrulation ectoderm blastocoel blastocoel endoderm gut blastoderm BLASTULA blastopore The Gut “internal, epithelium-lined cavity for the digestion and absorption of food sponges lack a gut simplest gut = blind sac (Cnidaria) blastopore gives rise to dual- function mouth/anus through-guts evolve later Protostome = blastopore contributes to the mouth Deuterostome = blastopore becomes the anus; mouth is a second opening Protostomy blastopore mouth anus Deuterostomy blastopore
    [Show full text]
  • Jonsc Vol2-7.PDF
    http://www.natsca.org Journal of Natural Science Collections Title: 100 years of deep‐sea tube worms in the collections of the Natural History Museum, London Author(s): Sherlock, E., Neal, L. & Glover, A. Source: Sherlock, E., Neal, L. & Glover, A. (2014). 100 years of deep‐sea tube worms in the collections of the Natural History Museum, London. Journal of Natural Science Collections, Volume 2, 47 ‐ 53. URL: http://www.natsca.org/article/2079 NatSCA supports open access publication as part of its mission is to promote and support natural science collections. NatSCA uses the Creative Commons Attribution License (CCAL) http://creativecommons.org/licenses/by/2.5/ for all works we publish. Under CCAL authors retain ownership of the copyright for their article, but authors allow anyone to download, reuse, reprint, modify, distribute, and/or copy articles in NatSCA publications, so long as the original authors and source are cited. Journal of Natural Science Collections 2015: Volume 2 100 years of deep-sea tubeworms in the collections of the Natural History Museum, London Emma Sherlock, Lenka Neal & Adrian G. Glover Life Sciences Department, The Natural History Museum, Cromwell Rd, London SW7 5BD, UK Received: 14th Sept 2014 Corresponding author: [email protected] Accepted: 18th Dec 2014 Abstract Despite having being discovered relatively recently, the Siboglinidae family of poly- chaetes have a controversial taxonomic history. They are predominantly deep sea tube- dwelling worms, often referred to simply as ‘tubeworms’ that include the magnificent me- tre-long Riftia pachyptila from hydrothermal vents, the recently discovered ‘bone-eating’ Osedax and a diverse range of other thin, tube-dwelling species.
    [Show full text]
  • Introduction to the Bilateria and the Phylum Xenacoelomorpha Triploblasty and Bilateral Symmetry Provide New Avenues for Animal Radiation
    CHAPTER 9 Introduction to the Bilateria and the Phylum Xenacoelomorpha Triploblasty and Bilateral Symmetry Provide New Avenues for Animal Radiation long the evolutionary path from prokaryotes to modern animals, three key innovations led to greatly expanded biological diversification: (1) the evolution of the eukaryote condition, (2) the emergence of the A Metazoa, and (3) the evolution of a third germ layer (triploblasty) and, perhaps simultaneously, bilateral symmetry. We have already discussed the origins of the Eukaryota and the Metazoa, in Chapters 1 and 6, and elsewhere. The invention of a third (middle) germ layer, the true mesoderm, and evolution of a bilateral body plan, opened up vast new avenues for evolutionary expan- sion among animals. We discussed the embryological nature of true mesoderm in Chapter 5, where we learned that the evolution of this inner body layer fa- cilitated greater specialization in tissue formation, including highly specialized organ systems and condensed nervous systems (e.g., central nervous systems). In addition to derivatives of ectoderm (skin and nervous system) and endoderm (gut and its de- Classification of The Animal rivatives), triploblastic animals have mesoder- Kingdom (Metazoa) mal derivatives—which include musculature, the circulatory system, the excretory system, Non-Bilateria* Lophophorata and the somatic portions of the gonads. Bilater- (a.k.a. the diploblasts) PHYLUM PHORONIDA al symmetry gives these animals two axes of po- PHYLUM PORIFERA PHYLUM BRYOZOA larity (anteroposterior and dorsoventral) along PHYLUM PLACOZOA PHYLUM BRACHIOPODA a single body plane that divides the body into PHYLUM CNIDARIA ECDYSOZOA two symmetrically opposed parts—the left and PHYLUM CTENOPHORA Nematoida PHYLUM NEMATODA right sides.
    [Show full text]
  • Actual Distribution of Bacteriocytes in the Trophosome of a Beard Worm
    Actual distribution of bacteriocytes in the trophosome of a beard worm (Oligobrachia mashikoi, Siboglinidae, Annelida): Clarification using whole-mount in situ hybridization 著者 Deguchi M., Kubota N., Matsuno A., Kanemori M., Fukumori Y., Sasayama Yuichi journal or Acta Zoologica publication title volume 88 number 2 page range 129-135 year 2007-04-01 URL http://hdl.handle.net/2297/6761 doi: 10.1111/j.1463-6395.2007.00260.x In situ hybridisation in beard worm ・ Deguchi et al. Actual distribution of bacteriocytes in the trophosome of a beard worm (Oligobrachia mashikoi, Siboglinidae, Annelida): Clarification using whole-mount in situ hybridisation M. Deguchi, N. Kubota, A. Matsuno1, M. Kanemori, Y. Fukumori and Y. Sasayama2 Department of Life Science, Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa 920-1192, Japan; 1Department of Biological Science, Faculty of Life and Environmental Science, Shimane University, Matsue 690-0823, Japan; 2Noto Marine Laboratory, Institute of Nature and Environmental Technology, Kanazawa University, Kanazawa 920-1192, Japan Key words: beard worms, symbiotic bacteria, 16S rRNA, in situ hybridisation Abstract M. Deguchi, N. Kubota, A. Matsuno, M. Kanemori, Y. Fukumori and Y. Sasayama 2006. Actual distribution of bacteriocytes in the trophosome of a beard worm (Oligobrachia mashikoi, Siboglinidae, Annelida): Clarification using whole-mount in situ hybridisation.―Acta Zoologica (Stockholm) Beard worms (Siboglinidae, Polycheata) lack a mouth and a digestive tract and harbour chaemosynthetic bacteria in the bacteriocytes of the trophosome. Since beard worms depend on the organic compounds produced by the bacteria for nourishment, the bacteriocytes should be efficient in exchanging various substances with body fluids. For this reason, it is important to determine how the bacteriocytes are organised in the trophosome.
    [Show full text]
  • Biology 3 Animal Diversity
    Biology 3 Animal Diversity Dr. Terence Lee Protostomes and Deuterostomes Symmetry • Asymmetry – no symmetry • Radial Symmetry – circular or round • Bilateral Symmetry – usually has a head and tail 1 Sponges • Asymmetrical • No true tissues Jellies • Ctenophores • Cnidarians Cnidarians • Named after their stinging cells • Radially symmetrical • First true tissues 2 Cnidarians Sea Anemone Coral Coral Reef Alternation of Generations Protostomes and Deuterostomes 3 Protostomes and Deuterostomes • Name comes from embryonic development – Protostome = As the embryo develops, the first opening becomes the mouth – Deuterostome = As embryo develops, the first opening becomes the anus . The Worms 1. Flatworms 2. Roundworms 3. Segmented Worms Flatworms • Playhelminthes – First with bilateral symmetry – Only one opening to gut planarians 4 Round Worms • Nematoda – One-way digestive tract 5 Nematodes Segmented Worms •Annelids –Body is divided into sections –Lives in many different habitats Annelids • Polychaetes are marine worms • Means “many feet” 6 Annelids This plan most Mollusks resembles the chiton body plan • Major Characteristics 1. Mantle – secretes the shell Mollusks • Live in very diverse habitats (aquatic and terrestrial) • Very diverse body plans – Some have shells while others are soft bodied • Very diverse locomotion 7 Mollusks Types of Mollusks: 1.Chitons – this is the most primitive 2.Bivalves – clams, oysters, mussels, etc. Chitons Bivalves • Two shells attached by a hinge • All are filter feeders • Mostly immobile but some species
    [Show full text]
  • Lack of Support for Deuterostomia Prompts Reinterpretation of the First Bilateria. Authors and Affiliations Paschalia Kapli1, Pa
    bioRxiv preprint doi: https://doi.org/10.1101/2020.07.01.182915; this version posted July 2, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 1 Lack of support for Deuterostomia prompts reinterpretation of the first Bilateria. 2 3 Authors and Affiliations 4 Paschalia Kapli1, Paschalis Natsidis1, Daniel J. Leite1, Maximilian Fursman1,&, Nadia Jeffrie1, 5 Imran A. Rahman2, Hervé Philippe3, Richard R. Copley4, Maximilian J. Telford1* 6 7 1. Centre for Life’s Origins and Evolution, Department of Genetics, Evolution and Environment, 8 University College London, Gower Street, London WC1E 6BT, UK 9 10 2. Oxford University Museum of Natural History, Parks Road, Oxford OX1 3PW, UK 11 3. Station d’Ecologie Théorique et Expérimentale, UMR CNRS 5321, Université Paul Sabatier, 12 09200 Moulis, France 13 4. Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), Sorbonne 14 Université, CNRS, 06230 Villefranche-sur-mer, France 15 & Current Address: Geology and Palaeoenvironmental Research Department, Institute of 16 Geosciences, Goethe University Frankfurt - Riedberg Campus, Altenhöferallee 1, 60438 17 Frankfurt am Main 18 19 20 21 22 23 *Correspondence: [email protected]. 1 bioRxiv preprint doi: https://doi.org/10.1101/2020.07.01.182915; this version posted July 2, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.
    [Show full text]
  • Six Major Steps in Animal Evolution: Are We Derived Sponge Larvae?
    EVOLUTION & DEVELOPMENT 10:2, 241–257 (2008) Six major steps in animal evolution: are we derived sponge larvae? Claus Nielsen Zoological Museum (The Natural History Museum of Denmark, University of Copenhagen), Universitetsparken 15, DK-2100 Copenhagen, Denmark Correspondence (email: [email protected]) SUMMARY A review of the old and new literature on animal became sexually mature, and the adult sponge-stage was morphology/embryology and molecular studies has led me to abandoned in an extreme progenesis. This eumetazoan the following scenario for the early evolution of the metazoans. ancestor, ‘‘gastraea,’’ corresponds to Haeckel’s gastraea. The metazoan ancestor, ‘‘choanoblastaea,’’ was a pelagic Trichoplax represents this stage, but with the blastopore spread sphere consisting of choanocytes. The evolution of multicellularity out so that the endoderm has become the underside of the enabled division of labor between cells, and an ‘‘advanced creeping animal. Another lineage developed a nervous system; choanoblastaea’’ consisted of choanocytes and nonfeeding cells. this ‘‘neurogastraea’’ is the ancestor of the Neuralia. Cnidarians Polarity became established, and an adult, sessile stage have retained this organization, whereas the Triploblastica developed. Choanocytes of the upper side became arranged in (Ctenophora1Bilateria), have developed the mesoderm. The a groove with the cilia pumping water along the groove. Cells bilaterians developed bilaterality in a primitive form in the overarched the groove so that a choanocyte chamber was Acoelomorpha and in an advanced form with tubular gut and formed, establishing the body plan of an adult sponge; the pelagic long Hox cluster in the Eubilateria (Protostomia1Deuterostomia). larval stage was retained but became lecithotrophic. The It is indicated that the major evolutionary steps are the result of sponges radiated into monophyletic Silicea, Calcarea, and suites of existing genes becoming co-opted into new networks Homoscleromorpha.
    [Show full text]
  • From a Flatworm, New Clues on Animal Origins
    G ince the turn of the twentieth cen- separate mouth and anus, a central nervous R An obscure group of tiny E B tury, zoologists have set out from system and organs to filter waste. Although L L A W coastal marine stations at dawn to creatures takes centre stage the position of acoels has moved around . sieve peppercorn-sized worms from in a battle to work out the a bit over the decades, a DNA analysis in A Ssea-bottom muck. These creatures, called 1999 (ref. 2) and several since then have acoels, often look like unremarkable splashes tree of life. placed them back in their earlier spot. In of paint when seen through a microscope. But particular, a genetic study of 94 organisms they represent a crucial stage in animal evolu- BY AMY MAXMEN in 2009 solidified the conclusion that acoels tion — the transition some 560 million years belonged at the very base of the bilaterians3. ago from simple anemone-like organisms to crucial intermediate stage of animal evolution. That study, led by Andreas Hejnol, a devel- the zoo of complex creatures that populate the Some researchers complain that the evidence opmental biologist at the Sars International world today. is not strong enough to warrant such a dra- Centre for Marine Molecular Biology in There are about 370 species of acoel, which matic rearrangement of the evolutionary tree, Bergen, Norway, confirmed that acoels and gets its name because it lacks a coelom — the and claim that the report leaves out key data. their kin occupied an intermediate spot fluid-filled body cavity that holds the internal In any case, the vehemence of the debate shows between cnidarians and the more-complex organs in more-complex animals.
    [Show full text]
  • Deuterostome Animals 34
    34_free_ch34.qxp 10/9/09 9:24 AM Page 773 THE DIVERSIFICATION OF LIFE UNIT 6 Deuterostome Animals 34 KEY CONCEPTS The most species-rich deuterostome lineages are the echinoderms and the vertebrate groups called ray-finned fishes and tetrapods. Echinoderms and vertebrates have unique body plans. Echinoderms are radially symmetric as adults and have a water vascular system. All vertebrates have a skull and an extensive endoskeleton made of cartilage or bone. The diversification of echinoderms was triggered by the evolution of appendages called podia; the diversification of vertebrates was driven by the evolution of the jaw and limbs. Humans are a tiny twig on the tree of life. Chimpanzees and humans diverged from a common ancestor that lived in Africa 6–7 million years ago. Since then, at least In most habitats the “top predators”—meaning animals that prey on other animals and aren’t 14 humanlike species have existed. preyed upon themselves—are deuterostomes. he deuterostomes include the largest-bodied and some ticated livestock are key sources of protein in most cultures, of the most morphologically complex of all animals. and in the developing world agriculture is still based on the T They range from the sea stars that cling to dock pilings, power generated by oxen, horses, water buffalo, or mules. In to the fish that dart in and out of coral reefs, to the wildebeests industrialized countries, millions of people bird-watch, plan that migrate across the Serengeti Plains of East Africa. vacations around seeing large mammals in national parks, or Biologists are drawn to deuterostomes in part because of keep vertebrates as pets.
    [Show full text]