1,921 research outputs found

    Spicy food for the egg-cowries: the evolution of corallivory in the Ovulidae (Gastropoda: Cypraeoidea)

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    IntroductionHost-parasite associations provide very useful models to study adaptive processes. We investigated the interaction between carnivorous marine gastropods, the Ovulidae or egg-cowries, and their cnidarian food targets. Ovulidae (Fleming, 1828), is a family of specialized carnivorous caenogastropods that feed by browsing on octocorals (Anthozoa: Octocorallia: Malacalcyonacea and Scleralcyonacea) or, to a much lesser degree, on antipatharians (Anthozoa: Hexacorallia: Antipatharia) and Stylasteridae (Hydrozoa: Hydroidolina: Anthoathecata). Very scanty information is available on the phylogenetic relationships and the degree of specificity of the relationship with the cnidarians of this corallivorous lineage, especially for deep-water taxa.MethodsTo assess taxonomic identifications and investigate cnidarian/ovulid relationships in the context of their evolution, we generated an extensive molecular dataset comprising two mitochondrial (cox1 and 16S rDNA) and one nuclear gene (28S rDNA) from 524 specimens collected worldwide. The coral hosts of the ovulid species have been identified by integrating literature data with new records, employing morphological and/or molecular (the mitochondrial 16S rDNA and mtMSH, and the nuclear ITS2) markers.ResultsWe obtained a molecular phylogenetic framework for the Ovulidae, time-calibrated with nine reliable fossil records. An ancestral state reconstruction allowed to identify Hexacorallia or Hydroidolina as the most likely ancestral cnidarian host for the Ovulidae.DiscussionOur phylogenetic hypothesis revealed the existence of groups that do not completely correspond to the currently employed subfamilial arrangement. Concerning trophic ecology, while only pediculariines (Pedicularia and allied) are associated with hydrozoans (Stylasteridae), our results suggest that some ovulid lineages shifted independently between octocorals and hexacorals

    Nuevas aportaciones paleobotánicas al Jurásico del Norte de la Península Ibérica: implicaciones palinoestratigráficas y paleoecológicas

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    This doctoral thesis is based on new unpublished material excavated, prepared and studied by the author. The thesis is structured in seven chapters, including an introductory chapter and a final chapter with conclusions and general considerations. The main objectives of this thesis are (1) to provide new paleobotanical data from the Jurassic records of the northern Iberian Peninsula; (2) prospecting and excavation of new Jurassic deposits; (3) Study and identify the different fossils collected in the selected deposits; (4) Establish from the fossil record the reconstruction of the paleoclimatic and paleoenvironmental conditions during the Jurassic in the area; (5) develop paleoecological contextualization including the study of plant-insect interactions. The first chapter deals with the state of the art of Jurassic paleobotany and plant-insect interactions in the Iberian Peninsula and presents the bases to contextualize the following chapters. The second chapter deals with the discovery of a new flora with plant-insect interactions from the Middle Jurassic located on a volcanic island far from the mainland, called Isla Camarena. The third chapter describes the palynological association of the aforementioned Middle Jurassic (paleo) island of Camarena. This chapter identifies a new palynological assemblage, including its palynostratigraphic analyses, which improves the dating of this unique site and also attempts to reconstruct the plant communities that inhabited this oceanic island, their possible colonization strategies, and the dispersal capabilities of some palynomorphs found on the island (paleo) The fourth chapter describes a new species of liverwort: Ricciopsis asturicus sp. nov. found in the Upper Jurassic (Kimmeridgian) of the Lastres Formation in Asturias, constituting the earliest evidence of the Ricciaceae Family in the Iberian Peninsula. The taxonomy of this group is also discussed, proposing the deletion of an earlier species of Ricciopsis. In addition, the paleogeographic distribution of the genus is interpreted, as well as its paleoecological implications. The fifth chapter describes and identifies the palynomorphs found in different sections of the Asturian Coast of Dinosaurs, discussing the palynostratigraphic implications for the formation. In addition, the botanical affinities of the palynomorphs are taken into account, presenting the reconstruction of the plant communities that formed the landscape of the Coast of the Dinosaurs of Asturias during the Kimmeridgian, and showing an approximation to the paleoclimatic and paleoenvironmental conditions of this formation. The sixth chapter consists of new flora and insect remains from a Late Jurassic hydrothermal paleoenvironment (J/K boundary). This flora was found in the Aguilar Formation and grew in a unique environment of hot springs. The seventh chapter evaluates the new findings and their implications for the knowledge of the Jurassic paleobotany of the Iberian Peninsula, as well as a projection of the future lines of research opened with the new contributions.Esta tese de doutoramento bas√©ase en novo material in√©dito escavado, elaborado e estudado polo autor. A tese estrut√ļrase en sete cap√≠tulos, inclu√≠ndo un cap√≠tulo introdutorio e un cap√≠tulo final con conclusi√≥ns e consideraci√≥ns xerais. Os obxectivos principais desta tese son (1) achegar novos datos paleobot√°nicos dos rexistros xur√°sicos do norte da Pen√≠nsula Ib√©rica; (2) prospecci√≥n e escavaci√≥n de novos xacementos xur√°sicos; (3) Estudar e identificar os diferentes f√≥siles recollidos nos xacementos seleccionados; (4) Establecer a partir do rexistro f√≥sil a reconstruci√≥n das condici√≥ns paleoclim√°ticas e paleoambientais durante o Xur√°sico na zona; (5) desenvolver a contextualizaci√≥n paleoecol√≥xica inclu√≠ndo o estudo das interacci√≥ns planta-insecto. O primeiro cap√≠tulo trata do estado da arte da paleobot√°nica xur√°sica e das interacci√≥ns planta-insecto na Pen√≠nsula Ib√©rica e pres√©ntanse as bases para contextualizar os cap√≠tulos seguintes. O segundo cap√≠tulo trata do descubrimento dunha nova flora con interacci√≥ns planta-insecto do Xur√°sico Medio situada nunha illa volc√°nica afastada do continente. No terceiro cap√≠tulo descr√≠bese a asociaci√≥n palinol√≥xica da mencionada illa (paleo) do xur√°sico medio de Camarena. Neste cap√≠tulo identif√≠case un novo conxunto palinol√≥xico, inclu√≠ndo as s√ļas an√°lises palinoestratigr√°ficas, que mellora a dataci√≥n deste singular xacemento e tenta reconstru√≠r as comunidades vexetais que habitaron esta illa oce√°nica, as s√ļas posibles estratexias de colonizaci√≥n e as capacidades de dispersi√≥n dalg√ļns palinomorfos atopados na illa oce√°nica. illa (paleo) O cuarto cap√≠tulo describe unha nova especie de hep√°tica: Ricciopsis asturicus sp. nov. atopado no Xur√°sico Superior (Kimmeridgiano) da Formaci√≥n Lastres en Asturias, constitu√≠ndo a evidencia m√°is antiga da Familia Ricciaceae na Pen√≠nsula Ib√©rica. Tam√©n se discute a taxonom√≠a deste grupo, propondo a eliminaci√≥n dunha especie anterior de Ricciopsis. Ademais, interpr√©tase a distribuci√≥n paleoxeogr√°fica do x√©nero, as√≠ como as s√ļas implicaci√≥ns paleoecol√≥xicas. O quinto cap√≠tulo describe e identifica os palinomorfos atopados en diferentes tramos da Costa Asturiana dos Dinosaurios, discutindo as implicaci√≥ns palinoestratigr√°ficas para a formaci√≥n. Ademais, t√©√Īense en conta as afinidades bot√°nicas dos palinomorfos, presentando a reconstruci√≥n das comunidades vexetais que conformaron a paisaxe da Costa dos Dinosaurios de Asturias durante o Kimmeridgiano, e mostrando unha aproximaci√≥n √°s condici√≥ns paleoclim√°ticas e paleoambientais desta formaci√≥n. . O sexto cap√≠tulo consta de novos restos de flora e insectos dun paleoambiente hidrotermal do Xur√°sico Tard√≠o (l√≠mite J/K). Esta flora foi atopada na Formaci√≥n Aguilar e medrou nun ambiente √ļnico de augas termais. No s√©timo cap√≠tulo aval√≠ase os novos achados e as s√ļas implicaci√≥ns para o co√Īecemento da paleobot√°nica xur√°sica da Pen√≠nsula Ib√©rica, as√≠ como unha proxecci√≥n das futuras li√Īas de investigaci√≥n abertas coas novas aportaci√≥ns.Esta tesis doctoral se basa en nuevo material in√©dito excavado, preparado y estudiado por el autor. La tesis est√° estructurada en siete cap√≠tulos, incluyendo un cap√≠tulo introductorio y un cap√≠tulo final con conclusiones y consideraciones generales. Los principales objetivos de esta tesis son (1) proporcionar nuevos datos paleobot√°nicos a partir de los registros del Jur√°sico del norte de la Pen√≠nsula Ib√©rica; (2) prospecci√≥n y excavaci√≥n de nuevos dep√≥sitos jur√°sicos; (3) Estudiar e identificar los diferentes f√≥siles recogidos en los yacimientos seleccionados; (4) Establecer a partir del registro f√≥sil la reconstrucci√≥n de las condiciones paleoclim√°ticas y paleoambientales durante el Jur√°sico en el √°rea; (5) desarrollar la contextualizaci√≥n paleoecol√≥gica incluyendo el estudio de las interacciones planta-insecto. El primer cap√≠tulo trata sobre el estado del arte de la paleobot√°nica del Jur√°sico y las interacciones planta-insecto de la Pen√≠nsula Ib√©rica y presenta las bases para contextualizar los cap√≠tulos siguientes. El segundo cap√≠tulo aborda el descubrimiento de una nueva flora con interacciones planta-insecto del Jur√°sico Medio ubicada en una isla volc√°nica alejada de tierra firme, llamada Isla Camarena. El tercer cap√≠tulo describe la asociaci√≥n palinol√≥gica de la referida isla del Jur√°sico Medio (paleo) de Camarena. Este cap√≠tulo identifica un nuevo conjunto palinol√≥gico, incluidos sus an√°lisis palinoestratigr√°ficos, que mejora la dataci√≥n de este singular sitio y tambi√©n trata de reconstruir las comunidades vegetales que habitaron esta isla oce√°nica, sus posibles estrategias de colonizaci√≥n y las capacidades de dispersi√≥n de algunos palinomorfos encontrados en la isla (paleo). El cuarto cap√≠tulo describe una nueva especie de hep√°tica: Ricciopsis asturicus sp. nov. encontrada en el Jur√°sico Superior (Kimmeridgiense) de la Formaci√≥n Lastres en Asturias constituyendo la evidencia m√°s temprana de la Familia Ricciaceae en la Pen√≠nsula Ib√©rica. Tambi√©n se discute la taxonom√≠a de este grupo, proponiendo la supresi√≥n de una especie anterior de Ricciopsis. Adem√°s, se interpreta la distribuci√≥n paleogeogr√°fica del g√©nero, as√≠ como sus implicaciones paleoecol√≥gicas. En el quinto cap√≠tulo se describen e identifican los palinomorfos encontrados en diferentes tramos de la Costa de los Dinosaurios de Asturias, discuti√©ndose las implicaciones palinoestratigr√°ficas para la formaci√≥n. Adem√°s, se tienen en cuenta las afinidades bot√°nicas de los palinomorfos, presentando la reconstrucci√≥n de las comunidades vegetales que formaron el paisaje de la Costa de los Dinosaurios de Asturias durante el Kimmeridgiense, y mostrando una aproximaci√≥n a las condiciones paleoclim√°ticas y paleoambientales de esta formaci√≥n. El sexto cap√≠tulo consiste en nueva flora y restos de insectos de un paleoambiente hidrotermal del Jur√°sico tard√≠o (l√≠mite J/K). Esta flora se encontr√≥ en la Formaci√≥n Aguilar y creci√≥ en un entorno √ļnico de aguas termales. El s√©ptimo cap√≠tulo eval√ļa los nuevos hallazgos y sus implicaciones para el conocimiento de la paleobot√°nica jur√°sica de la Pen√≠nsula Ib√©rica, as√≠ como una proyecci√≥n de las futuras l√≠neas de investigaci√≥n abiertas con las nuevas aportaciones.Xunta de Galicia | Ref. ED481A-2019/243Xunta de Galicia | Ref. ED431C- 2019/2

    AN ECOLOGICAL SURVEY OF EAST TEXAS SALAMANDERS ACROSS THE CAMP TYLER OUTDOOR FIELD SCHOOL IN SMITH COUNTY, TEXAS

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    Amphibians are a unique class of organisms with a very long and storied evolutionary history of survival. Many modern amphibian clades occupy several vital ecological roles within their native freshwater environments. One of these roles, typically includes functioning as an ecological indicator species, whereby the presence of stable and diverse populations of many amphibian species, including salamanders, within a freshwater ecosystem have long been considered ecological indicators of good habitat quality and stable ecosystem health. Similarly, salamanders also function as important members of their local food webs and act as valuable mediators of complex trophic hierarchies to facilitate nutrient cycling between trophic levels throughout their equally complex life histories. However, countless amphibians today are experiencing significant population declines ‚Äď with many sensitive and endemic species currently facing the imminent threat of widespread extinction events that are primarily driven by anthropogenic activities. Concerningly, this could also spell disaster for numerous other clades and communities within these same freshwater ecosystems. These changes in amphibian distribution and diversity are only one small component in many broad scale declines in global biodiversity that have been recognized in recent decades. These collective declines have been described as a ‚Äúsixth mass extinction.‚ÄĚ Because of their status as ecological indicator species, the widespread reduction in many amphibian communities may also serve as a harbinger of further biological crises in the near future. As a result, an updated record of sensitive amphibian species, especially salamanders, needs to be collected and compiled for use in assessing, tracking, and maintaining the health and well-being of many vital freshwater ecosystems. Here, a field survey of several East Texas salamander species was conducted from October of 2022 through April of 2023 ‚Äď during their peak activity season ‚Äď to create an updated inventory of historic and anecdotal salamander populations previously reported at the Camp Tyler Outdoor School, a local non-profit field school for grades K-12, located in Smith County, Texas. All three target salamander species were observed and identified during this period, although current findings seem to indicate that some these animals, especially the previously documented population of Western lesser sirens (Siren intermedia nettingi) may have experienced significant population declines since they were last surveyed. This is likely the result of a variety of ecological factors that have changed over time, including an increased anthropogenic presence within the area, land use changes, possible degradations in water and habitat quality, changing climatic conditions, and out competition with more tolerant clades in their aquatic environment

    Investigating tricky nodes in the Tree of Life

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    The Chapel Island Formation of Newfoundland (Canada) revisited: integrating ichnologic and sedimentologic datasets to unravel early metazoan evolution

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    The Chapel Island Formation (CIF) is a 1000+ m-thick, mainly siliciclastic succession that is well exposed along the coastline of Burin Peninsula, southeastern Newfoundland, eastern Canada. The CIF contains an outstanding record of latest Ediacaran-early Cambrian trace fossils with some intervals rich in small shelly fossils, and in 1992 the Fortune Head section was ratified by the International Commission on Stratigraphy (ICS) and the International Union of Geological Sciences (IUGS) as the Global Stratotype Section and Point (GSSP) for the Cambrian System. This was the first system-level GSSP defined primarily on the basis of trace fossils, a decision that evoked considerable discussion among the geological community. This thesis represents the first modern study of the sedimentology and the first taxonomic appraisal of the trace fossils since the original studies that proposed the GSSP in the 1980’s. More than 1700 m of CIF strata were logged in the sea cliffs of Burin Peninsula at Fortune Head, Fortune North, Grand Bank Head, Lewin’s Cove, Little Dantzic Cove, and Point May. A revision of the sedimentology permitted the description and interpretation of fourteen sedimentary facies composing five facies association (FA), which are interpreted to be deposited in: (1) mud-flat, mixed-flat, sand-flat, and tide-dominated or -influenced embayments (FA-A); (2) middle and lower shoreface (FA-B); (3) offshore transition, upper offshore, and lower offshore (FA-C); (4) shelf (stricto sensu) (FA-D); and (5) carbonate subtidal and intertidal environments (FA-E). An extensive trace-fossil dataset was built from careful field observations and provided a comprehensive record of bioturbation intensity (1596 data points on vertical bioturbation, 1481 data points on bedding plane bioturbation) and of trace-fossil metrics (3162 data points on burrow width, 1473 data points on burrow depth). In addition, a comprehensive revision of the trace-fossil composition (3508 trace fossils identified) allowed the description of twenty-eight ichnogenera and fifty-one ichnospecies, which correspond to cf. Allocotichnus dyeri, Archaeonassa fossulata, Arenicolites aff. carbonaria, Arenicolites isp., Bergaueria perata, B. cf. radiata, Circulichnis ligusticus, C. montanus, Cochlichnus anguineus, C. luguanensis, Conichnus conicus, Cruziana problematica, Curvolithus multiplex, C. simplex, Curvolithus isp., Dendroidichnites aff. irregulare, Didymaulichnus miettensis, Dimorphichnus isp. A, Dimorphichnus isp. B, cf. Dimorphichnus isp., ?Diplocraterion isp., Gordia marina, Gyrolithes gyratus, G. scintillus, Halopoa imbricata, Helminthoidichnites tenuis, Helminthopsis abeli, H. hieroglyphica, H. tenuis, Monomorphichnus bilinearis, M. lineatus, M. needleiunm, Monomorphichnus isp., Palaeophycus annulatus, P. tubularis, Palaeophycus isp., Psammichnites gigas circularis, P. cf. saltensis, Rosselia socialis, Rusophycus avalonensis, Rusophycus isp. A, Rusophycus isp. B, Saerichnites kutscheri comb. nov., Teichichnus rectus, Torrowangea rosei, Treptichnus bifurcus, T. coronatum, T. pedum, T. pollardi, Trichichnus linearis, and Trichichnus isp. Sectioning and polishing of 47 lithic samples from throughout the CIF showed that the sediment mixed layer that characterizes modern oceans developed through a series of steps that took place in the early Cambrian rather than in the Silurian as previously advocated. The main evolutionary innovations took place in the offshore environment with three paleoecologic stages that comprised: (1) an Ediacaran matground ecology, with surficial and very shallow infaunal grazing organisms living on and within microbially bound seafloors; (2) a Fortunian matground/firmground ecology, with a burst in behavioural and anatomical innovations and the first evidence of colonization of the shallow-tier; and (3) a late Fortunian/Cambrian Age 2 mixground ecology, with the development of a shallow mixed layer and deeper discrete burrows of the transition layer. Evaluation of outcrop quality based on accessibility, lateral and vertical continuity of beds, stratigraphic completeness, and type of exposure, demonstrated that Fortune Head, Fortune North, Grand Bank Head, and Little Dantzic Cove represented the best suited section to perform trace-fossil analyses, whereas Lewin’s Cove and Point May suffered from exposure biases affecting their trace-fossil records. The Ediacaran-Cambrian boundary interval was also studied in detail at Fortune Head, Grand Bank Head, Lewin’s Cove, and Point May, and the base of the Cambrian was placed confidently at the first appearance of trace fossils of the Treptichnus pedum Ichno-Assemblage Zone. This study demonstrates that only through detailed, comprehensive, and integrative approaches, can research provide new empirical evidence that further unfold our understanding of the history of animal life on Earth

    Global diversity of enterococci and description of 18 novel species

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    Bacteria of the genus Enterococcus colonize the guts of diverse animals. Some species have acquired multiple antibiotic resistances on top of a high level of intrinsic resistance and have emerged as leading causes of hospital-associated infection. Although clinical isolates of enterococcal species E. faecalis and E. faecium have been studied with respect to their antibiotic resistances and infection pathogenesis, comparatively little is known about the biology of enterococci in their natural context of the guts of humans and other land animals, including arthropods and other invertebrates. Importantly, little is also known about the global pool of genes already optimized for expression in an enterococcal background with the potential to be readily acquired by hospital adapted strains of E. faecalis and E. faecium , known facile exchangers of mobile genetic elements. We therefore undertook a global study designed to reach into maximally diverse habitats, to establish a first approximation of the genetic diversity of enterococci on Earth. Presumptive enterococci from over 900 diverse specimens were initially screened by PCR using a specific reporter gene that we found to accurately reflect genomic diversity. The genomes of isolates exceeding an operationally set threshold for diversity were then sequenced in their entirety and analyzed. This provided us with data on the global occurrence of many known enterococcal species and their association with various hosts and ecologies and identified 18 novel species expanding the diversity of the genus Enterococcus by over 25%. The 18 novel enterococcal species harbor a diverse array of genes associated with toxins, detoxification, and resource acquisition that highlight the capacity of the enterococci to acquire and adapt novel functions from diverse gut environments. In addition to the discovery and characterization of new species, this expanded diversity permitted a higher resolution analysis of the phylogenetic structure of the Enterococcus genus, including identification of distinguishing features of its 4 deeply rooted clades and genes associated with range expansion such as B-vitamin biosynthesis and flagellar motility. Collectively, this work provides an unprecedentedly broad and deep view of the genus Enterococcus , along with new insights into their potential threat to human health

    Forty years later: The status of the ‚ÄúBig Five‚ÄĚ mass extinctions

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    Over 40¬†years ago, Raup and Sepkoski identified five episodes of elevated extinction in the marine fossil record that were thought to be statistically distinct, thus warranting the term the ‚ÄúBig Five‚ÄĚ mass extinctions. Since then, the term has become part of standard vocabulary, especially with the naming of the current biodiversity crisis as the ‚Äúsixth mass extinction.‚ÄĚ However, there is no general agreement on which time intervals should be viewed as mass extinctions, in part because the Big Five turn out not to be statistically distinct from background rates of extinction, and in part, because other intervals of time have even higher extinction rates, in the Cambrian and early Ordovician. Nonetheless, the Big Five represent the five largest events since the early Ordovician, including in analyses that attempt to compensate for the incompleteness of the fossil and rock records. In the last 40¬†years, we have learned a great deal about the causes of many of the major and minor extinction events and are beginning to unravel the mechanisms that translated the initial environmental disturbances into extinction. However, for many of the events, further understanding will require going back to the outcrop, where the patchy distribution of environments and pervasive temporal gaps in the rock record challenge our ability to establish true extinction patterns. As for the current biodiversity crisis, there is no doubt that the rate of extinction is among the highest ever experienced by the biosphere, perhaps the second highest after the end-Cretaceous bolide impact. However (and fortunately), the absolute number of extinctions is still relatively small ‚Äď there is still time to prevent this becoming a genuine mass extinction. Given the arbitrariness of calling out the Big Five, perhaps the current crisis should be called the ‚Äúincipient Anthropocene mass extinction‚ÄĚ rather than the ‚Äúsixth mass extinction.

    Evolutionary diversification of defensins and cathelicidins in birds and primates

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    Divergent evolution for more than 310 million years has resulted in an avian immune system that is complex and more compact than that of primates, sharing much of its structure and functions. Not surprisingly, well conserved ancient host defense molecules, such as defensins and cathelicidins, have diversified over time. In this review, we describe how evolution influenced the host defense peptides repertoire, its distribution, and the relationship between structure and biological functions. Marked features of primate and avian HDPs are linked to species-specific characteristics, biological requirements, and environmental challenge
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