Despite rapid advances in the study of metazoan evolutionary history 1, phylogenomic analyses have so far neglected a number of microscopic lineages that possess a unique combination of characters ...and are thus informative for our understanding of morphological evolution. Chief among these lineages are the recently described animal groups Micrognathozoa and Loricifera, as well as the two interstitial “Problematica” Diurodrilus and Lobatocerebrum 2. These genera show a certain resemblance to Annelida in their cuticle and gut 3, 4; however, both lack primary annelid characters such as segmentation and chaetae 5. Moreover, they show unique features such as an inverted body-wall musculature or a novel pharyngeal organ. This and their ciliated epidermis have led some to propose relationships with other microscopic spiralians, namely Platyhelminthes, Gastrotricha, and in the case of Diurodrilus, with Micrognathozoa 6, 7—lineages that are grouped by some analyses into “Platyzoa,” a clade whose status remains uncertain 1, 8–11. Here, we assess the interrelationships among the meiofaunal and macrofaunal members of Spiralia using 402 orthologs mined from genome and transcriptome assemblies of 90 taxa. Lobatocerebrum and Diurodrilus are found to be deeply nested members of Annelida, and unequivocal support is found for Micrognathozoa as the sister group of Rotifera. Analyses using site-heterogeneous substitution models further recover a lophophorate clade and position Loricifera + Priapulida as sister group to the remaining Ecdysozoa. Finally, with several meiofaunal lineages branching off early in the diversification of Spiralia, the emerging concept of a microscopic, acoelomate, direct-developing ancestor of Spiralia is reviewed.
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•Diurodrilus and Lobatocerebrum, two problematic meiofauna, are miniaturized annelids•Micrognathozoa, the newest-described animal phylum, is the sister group of Rotifera•Bayesian mixture models recover strong support for deep spiralian relationships•Two clades comprising Platyzoa form separate early branches in Spiralia
Laumer et al. reconstruct the phylogeny of Spiralia, the animal group including molluscs, annelids, flatworms, and many microscopic worms. The new tree suggests that some previously unsampled, interstitial Problematica originated through miniaturization from large-bodied ancestors but also implies a primarily interstitial origin for many lineages.
To describe how overweight and wasting prevalence varies with age among children under 5 years in low- and middle-income countries (LMICs).
We used data from nationally representative Demographic and ...Health Surveys and Multiple Indicator Cluster Surveys. Overweight and wasting prevalence were defined as the proportions of children presenting mean weight for length/height (WHZ) more than 2 standard deviations above or below 2 standard deviations from the median value of the 2006 WHO standards, respectively. Descriptive analyses include national estimates of child overweight and wasting prevalence, mean, and standard deviations of WHZ stratified by age in years. National results were pooled using the population of children aged under 5 years in each country as weight. Fractional polynomials were used to compare mean WHZ with both overweight and wasting prevalence.
Ninety national surveys from LMICs carried out between 2010 and 2019 were included. The overall prevalence of overweight declined with age from 6.3% for infants (aged 0-11 months) to 3.0% in 4 years olds (p = 0.03). In all age groups, lower prevalence was observed in low-income compared to upper-middle-income countries. Wasting was also more frequent among infants, with a slight decrease between the first and second year of life, and little variation thereafter. Lower-middle-income countries showed the highest wasting prevalence in all age groups. On the other hand, mean WHZ was stable over the first 5 years of life, but the median standard deviation for WHZ decreased from 1.39 in infants to 1.09 in 4-year-old children (p < 0.001). For any given value of WHZ, both overweight and wasting prevalence were higher in infants than in older children.
The higher values of WHZ standard deviations in infants suggest that declining prevalence in overweight and wasting by age may be possibly due to measurement error or rapid crossing of growth channels by infants.
Myrmecochory (seed dispersal by ants) is a unique seed dispersal syndrome among invertebrates. It comprises three main phases: seed removal, seed manipulation, and seed deposition. However, the ...contribution of each phase to seed and seedling fate remains unclear. Here, we experimentally quantified the effects of each phase of myrmecochory on seed germination and seedling establishment, the two most critical life history stages involved in plant recruitment. We established 30 sample points, and each included an adult Mabea fistulifera tree, an Atta sexdens nest entrance, and six seed depots. We monitored the germination of M. fistulifera seeds for 3 months and subsequently followed the growth and mortality of the resulting seedlings for 12 months. Only the dispersal distance influenced plant establishment, reducing seed germination and increasing seedling growth, but with no effect of seed manipulation and deposition site. Despite the contrasting effects of distance on seed germination and seedling growth, the positive effect of dispersal distance on seedling growth was ten times greater than the negative effect on seed germination. Moreover, A. sexdens behaved neither as granivore nor as herbivore of M. fistulifera seeds or seedlings, which suggests that seed dispersal by A. sexdens is advantageous to M. fistulifera. Thus, the joint occurrence of these two species in disturbed areas could have a positive effect on this pioneer plant population, which might promote forest regeneration.
Epoxy adhesives, widely used in multiple structural applications, are used in the milling tool industry to replace brazing and mechanical fastening when joining the cutting bits to the tool body; ...though their durability is still a concern. This work aims to evaluate and characterise the effect of environmental factors associated with a tool’s life cycle on the performance of these bonded joints. A gravimetric analysis was conducted on bulk adhesive plates for water, cutting emulsion and dielectric fluid to obtain diffusion and relaxation rates. Novel real joint shear specimens were developed to enable strength testing on joints which are comparable with the final application. These specimens were immersed in fluids and subjected to thermal cycles or a corrosive finishing surface treatment to simulate the tool’s life cycle. The joint’s resistance was then benchmarked. Lastly, a dimensional variation test was carried out on tool prototypes before and after ageing, showing no significant dimensional variation which could compromise the cutting performance of the tool. Overall, though it was possible to identify a decrease in strength of around 20% in most tests, joint strength was still within the values necessary for safe operation, with a large safety factor still being retained.
Overhead transmission lines are the most vulnerable components in electrical power systems. Therefore, to improve the electrical system availability and reliability, fault location should be ...performed as quickly and accurately as possible. This procedure consists of several steps, including fault detection and classification, which are essential to successfully locate the fault. Due to the importance of these two steps in protection schemes, different approaches have been proposed recently, such as algorithms based on Fourier Transform, Wavelet Transform, Statistical and Artificial Intelligence Techniques. Although they are all promising, they require complex formulations or high computational efforts. This paper proposes a method based on the Euclidean distance measure to perform the fault detection and classification functions, only by using voltage signals from the transmission line ends. The proposed method is simple and robust, not requiring complex formulation or significant computational effort. A large number of tests were performed, considering the power system under different operational conditions and fault characteristics such as fault resistance and fault inception angle, among others. The observed results showed that the proposed method is capable of accurately detecting and classifying faults, regardless of the power system condition or fault characteristic. The comprehensiveness and applicability of the proposed method was confirmed by means of two different transmission lines (line parameters, voltage level, and AC equivalent systems).
Understanding the environmental drivers of biodiversity persistence and community organization in natural ecosystems is of great importance for planning the conservation of those ecosystems. This ...comprehension is even more important in severely threatened ecosystems. In this context, we analyzed ant communities in tropical dry forests (TDFs) in Brazil. These forests are embedded within other biomes, such as Cerrado and Caatinga. In this study, we asked whether (i) ant species richness and composition changes between TDFs within different vegetation domains; (ii) whether ant species richness and β-diversity increase north-to-south, possibly related to changes in tree richness and tree density; and (iii) species replacement contributes relatively more to β-diversity than does nestedness. We found that species composition is unique to each TDF within different biomes, and that species richness and β-diversity differ among the vegetation domains, being smaller in the Caatinga. We also found that replacement contributes most to β-diversity, although this contribution is lower in Caatinga than in Cerrado. We show that regional context is the main driver of species diversity, which is likely to be driven by both historical and ecological mechanisms. By analyzing large spatial scale variation in TDF environmental characteristics, we were able to evaluate how ant diversity changes along an environmental gradient. The high levels of species replacement and unique species composition of each region indicates that, to fully conserve TDFs, we need to have various conservation areas distributed across the entire range of vegetation domains in which these forests can be found. Thus, we demonstrate that a landscape-wise planning is urgent and necessary in order to preserve tropical dry forests.
Metazoa comprises 35–40 phyla that include some 1.3 million described species. Phylogenetic analyses of metazoan interrelationships have progressed in the past two decades from those based on ...morphology and/or targeted-gene approaches using single and then multiple loci to the more recent phylogenomic approaches that use hundreds or thousands of genes from genome and transcriptome sequencing projects. A stable core of the tree for bilaterian animals is now at hand, and instability and conflict are becoming restricted to a key set of important but contentious relationships. Acoelomorph flatworms (Acoela + Nemertodermatida) and
Xenoturbella
are sister groups. The position of this clade remains controversial, with different analyses supporting either a sister-group relation to other bilaterians (=Nephrozoa, composed of Protostomia and Deuterostomia) or membership in Deuterostomia. The main clades of deuterostomes (Ambulacraria and Chordata) and protostomes (Ecdysozoa and Spiralia) are recovered in numerous analyses based on varied molecular samples, and also receive anatomical and developmental support. Outstanding issues in protostome phylogenetics are the position of Chaetognatha within the protostome clade, and the monophyly of a group of spiralians collectively named Platyzoa. In contrast to the broad consensus over key questions in bilaterian phylogeny, the relationships of the five main metazoan lineages—Porifera, Ctenophora, Placozoa, Cnidaria and Bilateria—remain subject to conflicting topologies according to different taxonomic samples and analytical approaches. Whether deep bilaterian divergences such as the split between protostome and deuterostome clades date to the Cryogenian or Ediacaran (and, thus, the extent to which the pre-Cambrian fossil record is incomplete) is sensitive to dating methodology.
A new genus and species of Loricifera,
Scaberiloricus samba
gen. et sp. nov., is described from the continental shelf and slope off Rio de Janeiro, Brazil. Adult morphology remains unknown for the ...new entity, but information is available from three different Higgins larval instars. The Higgins larva of the new species is characterised by a bulbous head and a slender, elongate trunk, separated by a constriction behind the head. The cuticle of the thorax and the posterior part of the head is characterised by numerous longitudinal zigzag folds. The new species and genus shows greatest morphological resemblance with
Wataloricus japonicus
, and a phylogenetic analysis based on Higgins larval morphological characters suggests that
Scaberiloricus
gen. nov.,
Wataloricus
,
Tenuiloricus
, and
Patuloricus
form a monophyletic group within Pliciloricidae. The analysis furthermore suggests that the Higgins larvae of
Scaberiloricus
gen. nov. and
Wataloricus
represent transitional, evolutionary stages towards the highly aberrant Shira larvae, found in species of
Tenuiloricus
and
Patuloricus
.
Abstract
Aim
We evaluated the effects of forest island size, isolation and area in the landscape driving temporal changes of insect biodiversity in a mountaintop forest archipelago. We expected that ...(i) in smaller, less isolated forest islands, changes in insect composition are more prominent, primarily driven by gains over time; (ii) more forest in the landscape leads to increased gains of vagile species over time, regardless of forest island size and isolation; (iii) less vagile groups undergo heterogenisation, while highly vagile groups experience homogenisation due to differing dispersal capabilities.
Location
Espinhaço Range Biosphere Reserve, Brazil.
Taxon
Insects.
Methods
We used ants, dung beetles, bees, wasps and butterflies as study models to represent a gradient of low‐to‐high dispersal capability. We evaluated the colonisation‐ and extirpation‐resultant components of temporal β‐diversity using area‐ and isolation‐related variables as predictors.
Results
Distinct colonisation‐ and extirpation‐resultant homogenisation and heterogenisation processes are acting according to each insect group, likely due to different dispersal capabilities. Species losses dominated in ants, with widespread and rare species being lost. Butterflies gained species, represented mainly by widespread species, leading to an increased colonisation‐resultant homogenisation. Distance to neighbouring forest islands was the underlying predictor affecting the temporal β‐diversity of insect groups, and also species gains and losses but differently according to the survey period. Effects of the forest amount in the landscape increased the temporal β‐diversity of bees and butterflies but decreased that of ants, dung beetles and wasps.
Main Conclusions
These findings provide valuable biogeographic insights into the complex interactions between forest island characteristics, landscape attributes, and dispersal capabilities that shape the temporal dynamics of insect biodiversity on mountaintops. Conserving the forest amount in the landscape and keeping forest connectivity among forest islands are necessary because the temporal dynamics of local colonisation and extirpation can depend on the organisms' dispersal capability.
Resumo
Objetivo
Avaliamos os efeitos do tamanho da ilha florestal, do isolamento e da área de floresta na paisagem que direcionam mudanças temporais na biodiversidade de insetos em um arquipélago florestal no topo de montanhas. Esperávamos que (i) em ilhas florestais menores e menos isoladas as mudanças na composição de insetos fossem mais proeminentes, impulsionadas principalmente por ganhos ao longo do tempo; (ii) maior quantidade de floresta na paisagem leva a maiores ganhos de espécies vágeis ao longo do tempo, independentemente do tamanho e isolamento das ilhas de floresta; (iii) grupos menos vágeis sofrem heterogeneização, enquanto grupos altamente vágeis sofrem homogeneização devido a diferentes capacidades de dispersão.
Localização
Reserva da Biosfera da Serra do Espinhaço, Brasil.
Táxon
Insetos.
Métodos
Usamos formigas, besouros rola‐bosta, abelhas, vespas e borboletas como modelos de estudo para representar um gradiente de capacidade de dispersão. Avaliamos os componentes de colonização e extirpação resultantes da diversidade β temporal usando variáveis relacionadas à área e ao isolamento como preditores.
Resultados
Processos distintos de homogeneização e heterogeneização resultantes de colonização e extirpação estão agindo nos distintos grupos de insetos, provavelmente devido a diferentes capacidades de dispersão. As perdas de espécies predominaram nas formigas, com espécies raras e generalizadas sendo perdidas. As borboletas ganharam espécies, representadas principalmente por espécies amplamente distribuídas, levando a um aumento da homogeneização resultante da colonização. A distância às ilhas florestais vizinhas foi o principal preditor que afetou a diversidade β temporal dos grupos de insetos, e também os ganhos e perdas de espécies, mas de forma diferente de acordo com o período da pesquisa. Os efeitos da quantidade de floresta na paisagem aumentaram a diversidade β temporal de abelhas e borboletas, mas diminuíram a de formigas, besouros rola‐bosta e vespas.
Principais conclusões
Estas descobertas fornecem percepções biogeográficas valiosas sobre as complexas interações entre as características das ilhas florestais, os atributos da paisagem e a capacidade de dispersão que moldam a dinâmica temporal da biodiversidade de insetos nos topos das montanhas. Conservar a quantidade de floresta na paisagem e manter a conectividade entre ilhas florestais é necessário pois a dinâmica temporal da colonização e extirpação local pode depender da capacidade de dispersão dos organismos.
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