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1.
Nat Commun ; 10(1): 3348, 2019 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-31350398

RESUMO

Most sponges have biomineralized spicules. Molecular clocks indicate sponge classes diverged in the Cryogenian, but the oldest spicules are Cambrian in age. Therefore, sponges either evolved spiculogenesis long after their divergences or Precambrian spicules were not amenable to fossilization. The former hypothesis predicts independent origins of spicules among sponge classes and presence of transitional forms with weakly biomineralized spicules, but this prediction has not been tested using paleontological data. Here, we report an early Cambrian sponge that, like several other early Paleozoic sponges, had weakly biomineralized and hexactine-based siliceous spicules with large axial filaments and high organic proportions. This material, along with Ediacaran microfossils containing putative non-biomineralized axial filaments, suggests that Precambrian sponges may have had weakly biomineralized spicules or lacked them altogether, hence their poor record. This work provides a new search image for Precambrian sponge fossils, which are critical to resolving the origin of sponge spiculogenesis and biomineralization.


Assuntos
Poríferos/metabolismo , Animais , Biomineralização , Fósseis , Paleontologia , Filogenia , Poríferos/classificação , Poríferos/ultraestrutura , Dióxido de Silício/metabolismo
2.
PLoS One ; 14(6): e0218086, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31188894

RESUMO

The evaluation of large amounts of digital image data is of growing importance for biology, including for the exploration and monitoring of marine habitats. However, only a tiny percentage of the image data collected is evaluated by marine biologists who manually interpret and annotate the image contents, which can be slow and laborious. In order to overcome the bottleneck in image annotation, two strategies are increasingly proposed: "citizen science" and "machine learning". In this study, we investigated how the combination of citizen science, to detect objects, and machine learning, to classify megafauna, could be used to automate annotation of underwater images. For this purpose, multiple large data sets of citizen science annotations with different degrees of common errors and inaccuracies observed in citizen science data were simulated by modifying "gold standard" annotations done by an experienced marine biologist. The parameters of the simulation were determined on the basis of two citizen science experiments. It allowed us to analyze the relationship between the outcome of a citizen science study and the quality of the classifications of a deep learning megafauna classifier. The results show great potential for combining citizen science with machine learning, provided that the participants are informed precisely about the annotation protocol. Inaccuracies in the position of the annotation had the most substantial influence on the classification accuracy, whereas the size of the marking and false positive detections had a smaller influence.


Assuntos
/métodos , Aprendizado Profundo , Processamento de Imagem Assistida por Computador/estatística & dados numéricos , Biologia Marinha/métodos , Animais , Organismos Aquáticos , Artrópodes/anatomia & histologia , Artrópodes/classificação , Cnidários/anatomia & histologia , Cnidários/classificação , Equinodermos/anatomia & histologia , Equinodermos/classificação , Humanos , Imageamento Tridimensional , Biologia Marinha/instrumentação , Moluscos/anatomia & histologia , Moluscos/classificação , Poríferos/anatomia & histologia , Poríferos/classificação
3.
Nat Commun ; 10(1): 992, 2019 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-30824706

RESUMO

Defining the organisation of species interaction networks and unveiling the processes behind their assembly is fundamental to understanding patterns of biodiversity, community stability and ecosystem functioning. Marine sponges host complex communities of microorganisms that contribute to their health and survival, yet the mechanisms behind microbiome assembly are largely unknown. We present the global marine sponge-microbiome network and reveal a modular organisation in both community structure and function. Modules are linked by a few sponge species that share microbes with other species around the world. Further, we provide evidence that abiotic factors influence the structuring of the sponge microbiome when considering all microbes present, but biotic interactions drive the assembly of more intimately associated 'core' microorganisms. These findings suggest that both ecological and evolutionary processes are at play in host-microbe network assembly. We expect mechanisms behind microbiome assembly to be consistent across multicellular hosts throughout the tree of life.


Assuntos
Interações entre Hospedeiro e Microrganismos/fisiologia , Microbiota/fisiologia , Poríferos/microbiologia , Animais , Bactérias/classificação , Bactérias/genética , Biodiversidade , Evolução Biológica , Ecologia , Microbiota/genética , Filogenia , Poríferos/classificação , RNA Ribossômico 16S/genética , Especificidade da Espécie , Simbiose
4.
Mar Drugs ; 17(2)2019 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-30759850

RESUMO

Marine natural products (MNPs) continue to be in the spotlight in the global drug discovery endeavor. Currently, more than 30,000 structurally diverse secondary metabolites from marine sources have been isolated, making MNPs a profound, renewable source to investigate novel drug compounds. Marine sponges of the genus Suberea (family: Aplysinellidae) are recognized as producers of bromotyrosine derivatives, which are considered distinct chemotaxonomic markers for the marine sponges belonging to the order Verongida. This class of compounds exhibits structural diversity, ranging from simple monomeric molecules to more complex molecular scaffolds, displaying a myriad of biological and pharmacological potentialities. In this review, a comprehensive literature survey covering the period of 1998⁻2018, focusing on the chemistry and biological/pharmacological activities of marine natural products from marine sponges of the genus Suberea, with special attention to the biogenesis of the different skeletons of halogenated compounds, is presented.


Assuntos
Poríferos/química , Animais , Produtos Biológicos/química , Produtos Biológicos/farmacologia , Descoberta de Drogas , Humanos , Poríferos/classificação , Poríferos/metabolismo
5.
Genome ; 62(1): 1-10, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30557098

RESUMO

African sponges, particularly freshwater sponges, are understudied relative to demosponges in most other geographical regions. Freshwater sponges (Spongillida) likely share a common ancestor; however, their evolutionary history, particularly during their radiation into endemic and allegedly cosmopolitan groups, is unclear. Freshwater sponges of at least 58 species of 17 genera and four families are described from Central and Eastern Africa, but the diversity is underestimated due to limited distinguishable morphological features. The discovery of additional cryptic species is very likely with the use of molecular techniques such as DNA barcoding. The Royal Museum of Central Africa (MRAC, Tervuren, Belgium) hosts one of the largest collections of (Central) African freshwater sponge type material. Type specimens in theory constitute ideal targets for molecular taxonomy; however, the success is frequently hampered by DNA degradation and deamination, which are a consequence of suboptimal preservation techniques. Therefore, we genotyped African demosponge holotype material of the MRAC with specific short primers suitable for degenerated tissue and compare the results with the current, morphology-based classification. Our results demonstrate the utility of minimalistic barcodes for identification of sponges, potentially enabling efficient identification of individuals in taxonomic or metabarcoding studies, and highlight inconsistencies in the current freshwater sponge classification.


Assuntos
Código de Barras de DNA Taxonômico/métodos , Filogenia , Poríferos/genética , Animais , Código de Barras de DNA Taxonômico/normas , Poríferos/classificação
7.
Sci Rep ; 8(1): 8090, 2018 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-29795402

RESUMO

Coral reefs harbor diverse assemblages of organisms yet the majority of this diversity is hidden within the three dimensional structure of the reef and neglected using standard visual surveys. This study uses Autonomous Reef Monitoring Structures (ARMS) and amplicon sequencing methodologies, targeting mitochondrial cytochrome oxidase I and 18S rRNA genes, to investigate changes in the cryptic reef biodiversity. ARMS, deployed at 11 sites across a near- to off-shore gradient in the Red Sea were dominated by Porifera (sessile fraction), Arthropoda and Annelida (mobile fractions). The two primer sets detected different taxa lists, but patterns in community composition and structure were similar. While the microhabitat of the ARMS deployment affected the community structure, a clear cross-shelf gradient was observed for all fractions investigated. The partitioning of beta-diversity revealed that replacement (i.e. the substitution of species) made the highest contribution with richness playing a smaller role. Hence, different reef habitats across the shelf are relevant to regional diversity, as they harbor different communities, a result with clear implications for the design of Marine Protected Areas. ARMS can be vital tools to assess biodiversity patterns in the generally neglected but species-rich cryptic benthos, providing invaluable information for the management and conservation of hard-bottomed habitats over local and global scales.


Assuntos
Organismos Aquáticos/classificação , Biodiversidade , Recifes de Corais , Ecossistema , Animais , Anelídeos/classificação , Anelídeos/citologia , Antozoários/classificação , Antozoários/citologia , Organismos Aquáticos/citologia , Organismos Aquáticos/fisiologia , Artrópodes/classificação , Artrópodes/citologia , Monitoramento Ambiental/normas , Oceano Índico , Crescimento Demográfico , Poríferos/classificação , Poríferos/citologia , Imagens de Satélites
8.
Glob Chang Biol ; 24(7): 3130-3144, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29505691

RESUMO

Ocean warming (OW) and ocean acidification (OA) are threatening coral reef ecosystems, with a bleak future forecast for reef-building corals, which are already experiencing global declines in abundance. In contrast, many coral reef sponge species are able to tolerate climate change conditions projected for 2100. To increase our understanding of the mechanisms underpinning this tolerance, we explored the lipid and fatty acid (FA) composition of four sponge species with differing sensitivities to climate change, experimentally exposed to OW and OA levels predicted for 2100, under two CO2 Representative Concentration Pathways. Sponges with greater concentrations of storage lipid, phospholipids, sterols and elevated concentrations of n-3 and n-6 long-chain polyunsaturated FA (LC PUFA), were more resistant to OW. Such biochemical constituents likely contribute to the ability of these sponges to maintain membrane function and cell homeostasis in the face of environmental change. Our results suggest that n-3 and n-6 LC PUFA are important components of the sponge stress response potentially via chain elongation and the eicosanoid stress-signalling pathways. The capacity for sponges to compositionally alter their membrane lipids in response to stress was also explored using a number of specific homeoviscous adaptation (HVA) indicators. This revealed a potential mechanism via which additional CO2 could facilitate the resistance of phototrophic sponges to thermal stress through an increased synthesis of membrane-stabilizing sterols. Finally, OW induced an increase in FA unsaturation in phototrophic sponges but a decrease in heterotrophic species, providing support for a difference in the thermal response pathway between the sponge host and the associated photosymbionts. Here we have shown that sponge lipids and FA are likely to be an important component of the sponge stress response and may play a role in facilitating sponge survival under future climate conditions.


Assuntos
Adaptação Fisiológica/fisiologia , Mudança Climática , Ácidos Graxos/metabolismo , Metabolismo dos Lipídeos , Poríferos/fisiologia , Estresse Fisiológico/fisiologia , Animais , Dióxido de Carbono , Membrana Celular/química , Recifes de Corais , Ácidos Graxos/análise , Lipídeos/análise , Poríferos/química , Poríferos/classificação , Água do Mar/química
9.
PLoS One ; 13(3): e0195001, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29596453

RESUMO

Sponge-cyanobacteria associations have attracted research interest from an ecological, evolutionary and biotechnological perspective. Current knowledge is, in its majority, "hidden" in metagenomics research studying the entire microbial communities of sponges, while knowledge on these associations is totally missing for certain geographic areas. In this study, we (a) investigated the occurrence of cyanobacteria in 18 sponge species, several of which are studied for the first time for their cyanobionts, from a previously unexplored eastern Mediterranean ecoregion, the Aegean Sea, (b) isolated sponge-associated cyanobacteria, and characterized them based on a polyphasic (morphological-morphometric and molecular phylogenetic analysis) approach, and (c) conducted a meta-analysis on the global diversity of sponge species hosting cyanobacteria, as well as the diversity of cyanobacterial symbionts. Our research provided new records for nine sponge species, previously unknown for this association, while the isolated cyanobacteria were found to form novel clades within Synechococcus, Leptolyngbyaceae, Pseudanabaenaceae, and Schizotrichaceae, whose taxonomic status requires further investigation; this is the first report of a Schizotrichaceae cyanobacterium associated with sponges. The extensive evaluation of the literature along with the new data from the Aegean Sea raised the number of sponge species known for hosting cyanobacteria to 320 and showed that the cyanobacterial diversity reported from sponges is yet underestimated.


Assuntos
Biodiversidade , Cianobactérias/fisiologia , Poríferos/microbiologia , Animais , Cianobactérias/classificação , Cianobactérias/genética , Região do Mediterrâneo , Filogenia , Poríferos/classificação , Poríferos/genética , RNA Ribossômico 16S/genética , Simbiose
10.
Bioessays ; 40(5): e1800029, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29575018

RESUMO

The biannual international workshop entitled "The diversification of early emerging metazoans: A window into animal evolution?" took place at the Evangelische Akademie Tutzing, Germany, 11-14. September 2017. It was organized by Thomas Bosch (Kiel), Thomas Holstein (Heidelberg), and Ulrich Technau (Vienna), and it was sponsored by the Deutsche Forschungsgemeinschaft (DFG). The meeting gathered over 140 researchers to discuss the contribution of non-bilaterian metazoan models (Porifera, Ctenophora, Placozoa, and Cnidaria) to our understanding of: a. The evolution of metazoan developmental processes; b. Fundamental molecular mechanisms underlying metazoan features; and c. The complex interactions that animals establish with their environment.


Assuntos
Evolução Biológica , Animais , Cnidários/classificação , Ctenóforos/classificação , Evolução Molecular , Alemanha , Filogenia , Placozoa/classificação , Poríferos/classificação
11.
Nutrients ; 10(1)2018 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-29301302

RESUMO

Pyrroloquinoline and guanidine-derived alkaloids present distinct groups of marine secondary metabolites with structural diversity that displayed potentialities in biological research. A considerable number of these molecular architectures had been recorded from marine sponges belonging to different marine genera, including Batzella, Crambe, Monanchora, Clathria, Ptilocaulis and New Caledonian starfishes Fromia monilis and Celerina heffernani. In this review, we aim to comprehensively cover the chemodiversity and the bioactivities landmarks centered around the chemical constituents exclusively isolated from these three marine genera including Batzella, Crambe and Monanchora over the period 1981-2017, paying a special attention to the polycyclic guanidinic compounds and their proposed biomimetic landmarks. It is concluded that these marine sponge genera represent a rich source of novel compounds with potential applications for cancer and other therapeutic areas.


Assuntos
Alcaloides/farmacologia , Antineoplásicos/farmacologia , Crambe (Esponja)/metabolismo , Guanidinas/farmacologia , Neoplasias/tratamento farmacológico , Poríferos/metabolismo , Pirróis/farmacologia , Quinolinas/farmacologia , Alcaloides/química , Alcaloides/isolamento & purificação , Animais , Antineoplásicos/química , Antineoplásicos/isolamento & purificação , Crambe (Esponja)/classificação , Guanidinas/química , Guanidinas/isolamento & purificação , Humanos , Mimetismo Molecular , Estrutura Molecular , Neoplasias/metabolismo , Neoplasias/patologia , Poríferos/classificação , Pirróis/química , Pirróis/isolamento & purificação , Quinolinas/química , Quinolinas/isolamento & purificação , Relação Estrutura-Atividade
12.
Microb Ecol ; 75(1): 239-254, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28699015

RESUMO

Previously, it was believed that the prokaryote communities of typical 'low-microbial abundance' (LMA) or 'non-symbiont harboring' sponges were merely subsets of the prokaryote plankton community. Recent research has, however, shown that these sponges are dominated by particular clades of Proteobacteria or Cyanobacteria. Here, we expand on this research and assess the composition and putative functional profiles of prokaryotic communities from LMA sponges collected in two ecosystems (coral reef and hydrothermal vent) from vicinal islands of Taiwan with distinct physicochemical conditions. Six sponge species identified as Acanthella cavernosa (Bubarida), Echinodictyum asperum, Ptilocaulis spiculifer (Axinellida), Jaspis splendens (Tetractinellida), Stylissa carteri (Scopalinida) and Suberites sp. (Suberitida) were sampled in coral reefs in the Penghu archipelago. One sponge species provisionally identified as Hymeniacidon novo spec. (Suberitida) was sampled in hydrothermal vent habitat. Each sponge was dominated by a limited set of operational taxonomic units which were similar to sequences from organisms previously obtained from other LMA sponges. There was a distinct bacterial community between sponges collected in coral reef and in hydrothermal vents. The putative functional profile revealed that the prokaryote community from sponges collected in hydrothermal vents was significantly enriched for pathways related to DNA replication and repair.


Assuntos
Bactérias/isolamento & purificação , Fontes Hidrotermais/microbiologia , Poríferos/microbiologia , Animais , Bactérias/classificação , Bactérias/genética , Biodiversidade , Recifes de Corais , Ecossistema , Filogenia , Poríferos/classificação , Taiwan
13.
Environ Microbiol Rep ; 10(1): 80-91, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29194987

RESUMO

Marine sponges are benthic 'filter-feeding' invertebrates that can host dense and diverse bacterial, archaeal and eukaryotic communities. Due to the finding of several genes encoding symbiosis factors, such as adhesins, ankyrin repeats and tetratricopeptide repeats, the candidate phylum 'Poribacteria' is considered as a promising model microorganism for studying the origin of host-symbiont interactions in sponges. However, relatively little is known about its global diversity and phylogenetic distribution among different sponge hosts. Therefore, in this study we investigated phylogenetic relationships among poribacterial phylotypes and generated a phylogenetic network to examine the distribution and intraspecific diversity of the phylotypes between phylogenetically divergent host-sponges at a global scale. For this study 361 poribacterial 16S rRNA gene sequences obtained by Sanger sequencing from 15 different countries and 8 marine regions were gathered. We could demonstrate that the candidate phylum 'Poribacteria' is composed of diverse phylotypes, which are distributed among a wide range of phylogenetically divergent sponge hosts. The current phylogenetic analyses found neither conclusive evidence for co-speciation with its hosts, nor biogeographical correlation. Moreover, we identified a novel poribacterial clade, which might represent a link between the previously established four 'Poribacteria' clades.


Assuntos
Bactérias/classificação , Filogenia , Poríferos/microbiologia , Animais , Bactérias/genética , Biodiversidade , DNA Bacteriano/genética , Genoma Bacteriano/genética , Dados de Sequência Molecular , Poríferos/classificação , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
14.
PLoS One ; 12(12): e0189357, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29267311

RESUMO

The sponge fauna has been largely overlooked in the Archipelago of Hawai'i, notwithstanding the paramount role of this taxon in marine ecosystems. The lack of knowledge about Porifera populations inhabiting the Hawai'ian reefs limits the development of ecological studies aimed at understanding the functioning of these marine systems. Consequently, this project addresses this gap by describing the most representative sponge species in the shallow waters of the enigmatic bay of Kane'ohe Bay, in O'ahu Island. A total of 30 species (28 demosponges and two calcareous sponges) living associated to the reef structures are here reported. Six of these species are new records to the Hawai'ian Porifera catalogue and are suspected to be recent introductions to these islands. Morphological descriptions of the voucher specimens are provided, along with sequencing data of two partitions involving the mitochondrial cytochrome oxidase subunit 1 (COI) marker and a fragment covering partial (18S and 28S) and full (ITS-1, 5.8S and ITS-2) nuclear ribosomal genes. Species delimitations based on genetic distances were calculated to valitate how taxonomic assignments from DNA barcoding aligned with morphological identifications. Of the 60 sequences submitted to GenBank ~88% are the first sequencing records for the corresponding species and genetic marker. This work compiles the first catalogue combining morphological characters with DNA barcoding of Hawai'ian sponges, and contributes to the repository of public databases through the Sponge Barcoding Project initiative.


Assuntos
Código de Barras de DNA Taxonômico , Poríferos/classificação , Animais , Complexo IV da Cadeia de Transporte de Elétrons/genética , Hawaii , Microscopia Eletrônica de Varredura , Filogenia , Reação em Cadeia da Polimerase , Poríferos/genética , Especificidade da Espécie
15.
Curr Biol ; 27(24): 3864-3870.e4, 2017 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-29199080

RESUMO

The relationships at the root of the animal tree have proven difficult to resolve, with the current debate focusing on whether sponges (phylum Porifera) or comb jellies (phylum Ctenophora) are the sister group of all other animals [1-5]. The choice of evolutionary models seems to be at the core of the problem because Porifera tends to emerge as the sister group of all other animals ("Porifera-sister") when site-specific amino acid differences are modeled (e.g., [6, 7]), whereas Ctenophora emerges as the sister group of all other animals ("Ctenophora-sister") when they are ignored (e.g., [8-11]). We show that two key phylogenomic datasets that previously supported Ctenophora-sister [10, 12] display strong heterogeneity in amino acid composition across sites and taxa and that no routinely used evolutionary model can adequately describe both forms of heterogeneity. We show that data-recoding methods [13-15] reduce compositional heterogeneity in these datasets and that models accommodating site-specific amino acid preferences can better describe the recoded datasets. Increased model adequacy is associated with significant topological changes in support of Porifera-sister. Because adequate modeling of the evolutionary process that generated the data is fundamental to recovering an accurate phylogeny [16-20], our results strongly support sponges as the sister group of all other animals and provide further evidence that Ctenophora-sister represents a tree reconstruction artifact. VIDEO ABSTRACT.


Assuntos
Evolução Biológica , Filogenia , Poríferos/classificação , Animais , Análise de Sequência de Proteína
16.
PLoS One ; 12(9): e0183002, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28892487

RESUMO

The homoscleromorph sponge Oscarella carmela, first described from central California, USA is shown to represent two superficially similar but both morphologically and phylogenetically distinct species that are co-distributed. We here describe a new species as Oscarella pearsei, sp. nov. and re-describe Oscarella carmela; the original description was based upon material from both species. Further, we correct the identification of published genomic/transcriptomic resources that were originally attributed to O. carmela, and present new Illumina-sequenced transcriptome assemblies for each of these species, and the mitochondrial genome sequence for O. pearsei sp. nov. Using SSU and LSU ribosomal DNA and the mitochondrial genome, we report the phylogenetic relationships of these species relative to other Oscarella species, and find strong support for the placement of O. pearsei sp. nov. in a distinct clade within genus Oscarella defined by the presence of spherulous cells that contain paracrystalline inclusions; O. carmela lacks this cell type. Oscarella pearsei sp. nov and O. carmela can be tentatively distinguished based upon gross morphological differences such as color, surface texture and extent of mucus production, but can be more reliably identified using mitochondrial and nuclear barcode sequencing, ultrastructural characteristics of cells in the mesohyl, and the morphology of the follicle epithelium which surrounds the developing embryo in reproductively active individuals.


Assuntos
Sequenciamento de Nucleotídeos em Larga Escala , Poríferos/genética , Simpatria/genética , Transcriptoma , Animais , California , Biologia Computacional/métodos , Código de Barras de DNA Taxonômico , Perfilação da Expressão Gênica , Genoma Mitocondrial , Filogenia , Poríferos/classificação
17.
Sci Rep ; 7(1): 5286, 2017 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-28706211

RESUMO

The two major extant groups of siliceous sponges, Demospongiae and Hexactinellida, are generally regarded as sister groups forming the clade Silicea, although the nature of their last common ancestor is uncertain. The fossil record contains a diverse range of basal demosponges that appear to have evolved from hexactine-bearing reticulosan ancestors, although a compelling morphological intermediate has not previously been discovered. Here we describe a new species of fossil sponge, Conciliospongia anjiensis gen. et sp. nov., from the Late Ordovician (~444 Ma) Anji Biota of South China. This species has a reticulate, tufted skeleton of minute monaxon spicules, characteristic of the fossil demosponge family Hazeliidae and modern heteroscleromorphs, with hexactine spicules and a globose body form inherited from reticulosan ancestors. This transitional morphology had previously been hypothesized in palaeontological studies. This morphological intermediate between two extant classes further confirms siliceous sponge monophyly and demosponge-hexactinellid spicule homology, and supports the primitive, stem-silicean interpretation of simpler-structured fossil reticulosans.


Assuntos
Evolução Molecular , Fósseis , Paleontologia , Filogenia , Poríferos/anatomia & histologia , Poríferos/classificação , Animais , Modelos Teóricos
19.
Curr Biol ; 27(7): 958-967, 2017 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-28318975

RESUMO

Resolving the early diversification of animal lineages has proven difficult, even using genome-scale datasets. Several phylogenomic studies have supported the classical scenario in which sponges (Porifera) are the sister group to all other animals ("Porifera-sister" hypothesis), consistent with a single origin of the gut, nerve cells, and muscle cells in the stem lineage of eumetazoans (bilaterians + ctenophores + cnidarians). In contrast, several other studies have recovered an alternative topology in which ctenophores are the sister group to all other animals (including sponges). The "Ctenophora-sister" hypothesis implies that eumetazoan-specific traits, such as neurons and muscle cells, either evolved once along the metazoan stem lineage and were then lost in sponges and placozoans or evolved at least twice independently in Ctenophora and in Cnidaria + Bilateria. Here, we report on our reconstruction of deep metazoan relationships using a 1,719-gene dataset with dense taxonomic sampling of non-bilaterian animals that was assembled using a semi-automated procedure, designed to reduce known error sources. Our dataset outperforms previous metazoan gene superalignments in terms of data quality and quantity. Analyses with a best-fitting site-heterogeneous evolutionary model provide strong statistical support for placing sponges as the sister-group to all other metazoans, with ctenophores emerging as the second-earliest branching animal lineage. Only those methodological settings that exacerbated long-branch attraction artifacts yielded Ctenophora-sister. These results show that methodological issues must be carefully addressed to tackle difficult phylogenetic questions and pave the road to a better understanding of how fundamental features of animal body plans have emerged.


Assuntos
Evolução Biológica , Genoma , Invertebrados/classificação , Filogenia , Poríferos/genética , Vertebrados/classificação , Animais , Genômica/métodos , Invertebrados/genética , Poríferos/classificação , Vertebrados/genética
20.
BMC Evol Biol ; 17(1): 82, 2017 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-28320321

RESUMO

BACKGROUND: Mitochondrial introns intermit coding regions of genes and feature characteristic secondary structures and splicing mechanisms. In metazoans, mitochondrial introns have only been detected in sponges, cnidarians, placozoans and one annelid species. Within demosponges, group I and group II introns are present in six families. Based on different insertion sites within the cox1 gene and secondary structures, four types of group I and two types of group II introns are known, which can harbor up to three encoding homing endonuclease genes (HEG) of the LAGLIDADG family (group I) and/or reverse transcriptase (group II). However, only little is known about sponge intron mobility, transmission, and origin due to the lack of a comprehensive dataset. We analyzed the largest dataset on sponge mitochondrial group I introns to date: 95 specimens, from 11 different sponge genera which provided novel insights into the evolution of group I introns. RESULTS: For the first time group I introns were detected in four genera of the sponge family Scleritodermidae (Scleritoderma, Microscleroderma, Aciculites, Setidium). We demonstrated that group I introns in sponges aggregate in the most conserved regions of cox1. We showed that co-occurrence of two introns in cox1 is unique among metazoans, but not uncommon in sponges. However, this combination always associates an active intron with a degenerating one. Earlier hypotheses of HGT were confirmed and for the first time VGT and secondary losses of introns conclusively demonstrated. CONCLUSION: This study validates the subclass Spirophorina (Tetractinellida) as an intron hotspot in sponges. Our analyses confirm that most sponge group I introns probably originated from fungi. DNA barcoding is discussed and the application of alternative primers suggested.


Assuntos
Código de Barras de DNA Taxonômico , Íntrons , Poríferos/genética , Animais , Sequência de Bases , Evolução Biológica , Endonucleases/genética , Mitocôndrias/genética , Fases de Leitura Aberta , Filogenia , Poríferos/classificação , Processamento de RNA
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