1,761 research outputs found
Osteology and chondrocranial morphology of Gastrophryne carolinensis (Anura: Microhylidae), with a review of the osteological diversity of New World microhylids
Microhylidae is a large, cosmopolitan anuran family. Recent molecular analyses have demonstrated the monophyly of the family—a conclusion that is supported by the larval morphology, coupled with the unique mode of tongue protrusion in adults, and a suite of osteological and myological characters seemingly associated with this innovation in feeding. Despite this functional constraint, osteological diversity probably exceeds that of any other anuran family, and this diversity is especially evident in the New Worldmicrohylids that comprise two clades, Gastrophryninae and Otophryninae. To facilitate comparisons among these clades, we describe the larval chondrocranium, skeletal development, and adult osteology of Gastrophryne carolinensis. We provide a phylogeneticcontext for these comparisons through a novel phylogenetic analysis of 45 microhylid genera based on data for one mitochondrial and three nuclear loci from previously published studies. Nearly all relationships within the monophyletic Gastrophryninae are resolvedwith robust support. Based on these results, we found that the larval chondrocrania of gastrophrynines share morphological features that distinguish them from Otophryne and other anurans. Among the adults, all gastrophrynines show evidence of an anterior shift ofthe jaws that is correlated with specializations in the otic region, and with the alignment of the planum antorbitale, the cartilage wall separating the nasal capsule from the orbits. The larval infrarostral and the adult mandibles lack a typical anuran mandibular symphysis, and the mentomeckelian bone of the adult is modified with a special process. The most variable part of the skull is the palate in which a neopalatine usually is absent and the vomer may be single or divided. The posteromedial processes of the hyoids of gastrophynines tend to be elaborated, and some taxa bear a peculiar transverse slit in the posterior part of the hyoid corpus. The anterior zonal elements of the pectoral girdle are reduced or absent, and the posterior parts enlarged and shifted posteriorly. Most taxa have eight presacral vertebrae; depending on the taxon the last presacral is amphicoelous or procoelous
Osteology and chondrocranial morphology of Gastrophryne carolinensis (Anura: Microhylidae), with a review of the osteological diversity of New World microhylids
Microhylidae is a large, cosmopolitan anuran family. Recent molecular analyses have demonstrated the monophyly of the family—a conclusion that is supported by the larval morphology, coupled with the unique mode of tongue protrusion in adults, and a suite of osteological and myological characters seemingly associated with this innovation in feeding. Despite this functional constraint, osteological diversity probably exceeds that of any other anuran family, and this diversity is especially evident in the New World microhylids that comprise two clades, Gastrophryninae and Otophryninae. To facilitate comparisons among these clades, we describe the larval chondrocranium, skeletal development, and adult osteology of Gastrophryne carolinensis. We provide a phylogenetic context for these comparisons through a novel phylogenetic analysis of 45 microhylid genera based on data for one mitochondrial and three nuclear loci from previously published studies. Nearly all relationships within the monophyletic Gastrophryninae are resolved with robust support. Based on these results, we found that the larval chondrocrania of gastrophrynines share morphological features that distinguish them from Otophryne and other anurans. Among the adults, all gastrophrynines show evidence of an anterior shift of the jaws that is correlated with specializations in the otic region, and with the alignment ofthe planum antorbitale, the cartilage wall separating the nasal capsule from the orbits. The larval infrarostral and the adult mandibles lack a typical anuran mandibular symphysis, andthe mentomeckelian bone of the adult is modified with a special process. The most variable part of the skull is the palate in which a neopalatine usually is absent and the vomer may be single or divided. The posteromedial processes of the hyoids of gastrophynines tend to be elaborated, and some taxa bear a peculiar transverse slit in the posterior part of thehyoid corpus. The anterior zonal elements of the pectoral girdle are reduced or absent, and the posterior parts enlarged and shifted posteriorly. Most taxa have eight presacral vertebrae;depending on the taxon the last presacral is amphicoelous or procoelous.A família Microhylidae é muito diversificada e cosmopolita. Análises moleculares recentes demonstraram seu monofiletismo—uma conclusão sustentada pela morfologia larval, ao lado do modo único de protrusão da língua nos adultos e de um conjunto de características osteológicas e miológicas aparentemente associadas à essa inovação na alimentação. Apesar dessa restrição funcional, a diversidade osteológica provavelmente excede à de qualquer outra família de anuros, e essa diversidade é especialmente evidente nos Microhylidae do Novo Mundo de dois clados, Gastrophryninae e Otophryninae. Para facilitar as comparações entre esses clados, descrevemos aqui o condrocrânio larval, o desenvolvimento do esqueleto e a osteologia do adulto de Gastrophryne carolinensis. Fornecemos um contexto filogenético para essas comparações por meio de uma nova análise filogenética de 45 gêneros de Microhylidae baseada em dados de um locus mitocondrial e três loci nucleares obtidos em estudos prévios publicados. Quase todas as relações dentro do grupo monofilético Gastrophryninae são robustamente suportadas. Com base nesses resultados, concluímos que os condrocrânios das larvas dos Gastrophryninae compartilham características morfológicas que os distingue de Otophryne e de outros anuros. Entre os adultos, todos os Gastrophryninae mostramevidências de uma mudança na parte anterior das maxilas relacionada a especializações na região ótica e ao alinhamento do planum antorbitale, a parede de cartilagem que separa a cápsula nasal das órbitas. Os infra-rostrais das larvas e as mandíbulas dos adultosm são desprovidos de uma sínfisemandibular típica dos anuros, e o osso mentomeckeliano do adulto é modificado com um processo especial. A porção mais variável do crânio é o palato, no qual o neopalatino geralmente está ausente e o vômer pode ser simples ou dividido. Os processos póstero-mediais dos hióides dos Gastrophyninaetendem a ser elaborados, e alguns táxons possuem uma fenda transversal peculiar na porção posterior do corpo do hióide. Os elementos zonais anteriores da cintura escapular são reduzidos ou ausentes, e as porções posteriores, aumentadas e deslocadas posteriormente. A maioria dos táxons possui oito vértebras pré-sacrais; dependendo do táxon, as última vértebra pré-sacral é anficélica ou procélica
The vertebrate fauna of the Upper Permian of Niger — II, Preliminary description of a new pareiasaur
Main articleThe skull of a new pareiasaur, Bunostegos akokanensis gen. et sp. nov., is described on the basis of a partial skull from the Upper Permian
Moradi Formation of north-central Niger. Autapomorphies of the genus include the presence of three hemispherical bosses at the tip of
the snout, an enlarged laterally projecting supraorbital boss positioned on each postfrontal, and additional, smaller bosses on the
squamosal and supratemporal bones. Bunostegos is further characterized by a tab-like process of the nasal that articulates with the
frontal, a pineal foramen located equidistant between the parietal-frontal and parietal-postparietal sutural contacts, a postparietal that
is excluded from the caudal margin of the dorsal skull roof, and a blunt interpterygoid vacuity. The discovery of Bunostegos suggests an
unsuspected degree of biogeographic endemism for central West Africa during the Late Permian.Non
Early Limb Patterning in the Direct‐Developing Salamander Plethodon Cinereus Revealed by Sox9 and Col2a1
Direct‐developing amphibians form limbs during early embryonic stages, as opposed to the later, often postembryonic limb formation of metamorphosing species. Limb patterning is dramatically altered in direct‐developing frogs, but little attention has been given to direct‐developing salamanders. We use expression patterns of two genes, sox9and col2a1, to assess skeletal patterning during embryonic limb development in the direct‐developing salamander Plethodon cinereus. Limb patterning in P. cinereus partially resembles that described in other urodele species, with early formation of digit II and a generally anterior‐to‐posterior formation of preaxial digits. Unlike other salamanders described to date, differentiation of preaxial zeugopodial cartilages (radius/tibia) is not accelerated in relation to the postaxial cartilages, and there is no early differentiation of autopodial elements in relation to more proximal cartilages. Instead, digit II forms in continuity with the ulnar/fibular arch. This amniote‐like connectivity to the first digit that forms may be a consequence of the embryonic formation of limbs in this direct‐developing species. Additionally, and contrary to recent models of amphibian digit identity, there is no evidence of vestigial digits. This is the first account of gene expression in a plethodontid salamander and only the second published account of embryonic limb patterning in a direct‐developing salamander species
Relações filogenéticas entre espécies de "Flectonotus" (Anura: Hemiphractidae) isoladas geograficamente reveladas por dados moleculares, de comportamento e morfológicos
Phylogenetic analyses of data derived from one mitochondrial gene and one nuclear gene show that the five species of small marsupial frogs currently recognized as Flectonotus are in fact two distinct and not closely related lineages. This conclusion is strongly supported by reproductive behavior and morphological characters. Thus, we recognize the genus Fritziana Mello-Leitão for the three species in southeastern Brazil and Flectonotus Miranda-Ribeiro for the two species in northern South America.Análises filogenéticas de dados derivados de um gene mitocondrial e um gene nuclear mostram que as cinco espécies de pererecas-marsupiais de pequeno porte atualmente incluídas no gênero Flectonotus pertencem, na verdade, a duas linhagens distintas e não intimamente aparentadas. Essa conclusão é fortemente sustentada por caracteres morfológicos e características do comportamento reprodutivo. Dessa forma, reconhecemos os gêneros Fritziana Mello-Leitão, para as três espécies do sudeste do Brasil, e Flectonotus Miranda-Ribeiro, para as duas espécies do norte da América do Sul
A new genus and species of frog from the Kem Kem (Morocco), the second neobatrachian from Cretaceous Africa
Neobatrachia, a clade representing the majority of extant anuran diversity, is thought to have emerged and diversified during the Cretaceous. Most of the early diversification of neobatrachians occurred in southern Gondwana, especially the regions that are today South America and Africa. Whereas five extinct neobatrachians have been described from the Cretaceous of South America in the last decade, only one is known from Africa. This difference in the known extinct diversity is linked to the lack of well-preserved specimens, understudy of fragmentary remains, and lack of known Cretaceous sites in Africa. Study of fragmentary anuran remains from Africa could allow for the identification of previously unknown neobatrachians, allowing for a better understanding of their early diversification. We reanalysed several previously described anuran specimens from the well-known Kem Kem beds, including using CT-scanning. Through our osteological study, we determined that several cranial bones and vertebrae represent a new hyperossified taxon for which we provide a formal description. Comparison to other hyperossified anurans revealed similarities and affinity of this new taxon with the neobatrachians Beelzebufo (extinct) and Ceratophrys (extant). Phylogenetic analyses supported this affinity, placing the new taxon within Neobatrachia in an unresolved clade of Ceratophryidae. This taxon is the oldest neobatrachian from Africa, and reveals that neobatrachians were already widespread throughout southern Gondwana during the earliest Late Cretaceous
A new species of Brachycephalus (Anura Brachycephalidae) from Santa Catarina, southern Brazil
A new species of Brachycephalus (Anura: Brachycephalidae) is described from the Atlantic Forest of northeastern state of Santa Catarina, southern Brazil. Nine specimens (eight adults and a juvenile) were collected from the leaf litter of montane forests 790–835 m above sea level (a.s.l.). The new species is a member of the pernix group by its bufoniform shape and the absence of dermal co-ossification and is distinguished from all its congeners by a combination of its general coloration (dorsal region of head, dorsum, legs, arms, and flanks light, brownish green to dark, olive green, with darker region in the middle of the dorsum and a white line along the vertebral column in most specimens) and by its smooth dorsum. The geographical distribution of the new species is highly reduced (extent of occurrence estimated as 25.04 ha, or possibly 34.37 ha). In addition, its habitat has experienced some level of degradation, raising concerns about the future conservation of the species. Preliminary density estimates suggest one calling individual every 3–4 m2 at 815–835 m a.s.l. and every 100 m2 at 790 m a.s.l. Together with the recently described B. boticario and B. fuscolineatus, the new species is among the southernmost species of Brachycephalus known to date
Cryptic diversity of a widespread global pathogen reveals expanded threats to amphibian conservation
Biodiversity loss is one major outcome of human-mediated ecosystem disturbance. One way that humans have triggered wildlife declines is by transporting disease-causing agents to remote areas of the world. Amphibians have been hit particularly hard by disease due in part to a globally distributed pathogenic chytrid fungus (Batrachochytrium dendrobatidis [Bd]). Prior research has revealed important insights into the biology and distribution of Bd; however, there are still many outstanding questions in this system. Although we know that there are multiple divergent lineages of Bd that differ in pathogenicity, we know little about how these lineages are distributed around the world and where lineages may be coming into contact. Here, we implement a custom genotyping method for a global set of Bd samples. This method is optimized to amplify and sequence degraded DNA from noninvasive skin swab samples. We describe a divergent lineage of Bd, which we call BdASIA3, that appears to be widespread in Southeast Asia. This lineage co-occurs with the global panzootic lineage (BdGPL) in multiple localities. Additionally, we shed light on the global distribution of BdGPL and highlight the expanded range of another lineage, BdCAPE. Finally, we argue that more monitoring needs to take place where Bd lineages are coming into contact and where we know little about Bd lineage diversity. Monitoring need not use expensive or difficult field techniques but can use archived swab samples to further explore the history—and predict the future impacts—of this devastating pathogen
Host lifestyle affects human microbiota on daily timescales
Background:
Disturbance to human microbiota may underlie several pathologies. Yet, we lack a comprehensive understanding of how lifestyle affects the dynamics of human-associated microbial communities.
Results:
Here, we link over 10,000 longitudinal measurements of human wellness and action to the daily gut and salivary microbiota dynamics of two individuals over the course of one year. These time series show overall microbial communities to be stable for months. However, rare events in each subjects’ life rapidly and broadly impacted microbiota dynamics. Travel from the developed to the developing world in one subject led to a nearly two-fold increase in the Bacteroidetes to Firmicutes ratio, which reversed upon return. Enteric infection in the other subject resulted in the permanent decline of most gut bacterial taxa, which were replaced by genetically similar species. Still, even during periods of overall community stability, the dynamics of select microbial taxa could be associated with specific host behaviors. Most prominently, changes in host fiber intake positively correlated with next-day abundance changes among 15% of gut microbiota members.
Conclusions:
Our findings suggest that although human-associated microbial communities are generally stable, they can be quickly and profoundly altered by common human actions and experiences.National Science Foundation (U.S.) (Grant 0821391
Handbook of Test Methods for Evaluating Chemical Deicers
This handbook contains a structured selection of specific test methods for complete characterization of deicing chemicals. Sixty-two specific test methods are defined for the evaluation of chemical deicers in eight principal property performance areas: 1) physicochemical characteristics; 2) deicing performance; 3) compatibility with bare and coated metals in concrete; 5) compatibility with concrete and nonmetals; 6) engineering parameters; 7) ecological effects; and 8) health and safety aspects.
The 62 specific chemical deicer test methods are composed of 12 primary and 50 supplementary test methods. The primary test methods, which were developed for conducting the more important evaluations, are identified as follows: 1) ice melting tests
for liquid and solid deicers; 2) ice penetration tests for liquid and solid deicers; 3) ice undercutting tests for liquid and solid deicers; 4) bare metal corrosion test; 5) concrete degradation test; 6) concrete scaling test; 7) friction characterization test; 8) ecological effects tests; and 9) rebar in concrete corrosion test. xx
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