A new genus and species of Hydrobiidae Stimpson, 1865 (Caenogastropoda, Truncatelloidea) from Peloponnese, Greece

Minute caenogastropod brackish-water gastropods, formerly classified as Hydrobia, are important elements of the brackish-water fauna and were objects of intensive study for many years. Until now, five genera have been distinguished, most of them represented by a number of species, but rather indistinguishable without molecular data (cytochrome oxidase subunit I – COI). In the eastern Mediterranean region, they are still poorly studied. In this paper, we present a new species of “Hydrobia” from the brackish Moustos spring, Arkadia, eastern Peloponnese, Greece. The shell, protoconch, radula, female reproductive organs, and penis are described and illustrated, together with the molecular (COI) relationships with other hydrobiids. All data confirm that these snails represent a distinct taxon, which must be classified as a new species belonging to a new genus. The formal descriptions are given. The closest, sister taxon is Salenthydrobia Wilke, 2003. The molecularly estimated time of divergence, 5.75 ± 0.49 Mya, coincides with 5.33 Mya, which is the time of the Oligocene flooding that terminated the Messinian salinity crisis. During the latter period, brackish “Lago-Mare” habitats were most probably suitable for the last common ancestor of Salenthydrobia and the newly described genus. Later, the Pliocene flooding isolated the Apennine and Peloponnese populations, promoting speciation.

A re-analysis of the data in Sharkey et al.’s (2021) minimalist revision reveals that BINs do not deserve names, but BOLD Systems needs a stronger commitment to open science

Halting biodiversity decline is one of the most critical challenges for humanity, but biodiversity assessment and monitoring are hampered by taxonomic impediments. We here distinguish between a “dark taxon impediment” caused by a large number of undescribed species and a “superficial description impediment” caused by species descriptions so imprecise that type specimens have to be consulted in order to resolve species identities. Recently, Sharkey et al. (2021) proposed to address the dark taxon impediment for Costa Rican braconid wasps by describing 403 species based on barcode clusters (“BINs”) computed by BOLD Systems. The default assumption of the revision is that BIN=Species (e.g., BOLD:ACM9419 becomes Bracon federicomatarritai Sharkey, sp. nov.) and therefore the diagnoses of most species consist only of a consensus barcode. We here argue that this type of “minimalist revision” is unnecessary and undesirable. It is unnecessary because barcode clusters (e.g. BINs) already provide grouping statements that overcome many of the obstacles associated with dark taxon impediments. However, minimalist revisions are also undesirable and problematic because the diagnoses are only based on one character system – that in the case of Sharkey et al. was poorly analyzed. Furthermore, the revision relies on units that violate basic rules of reproducibility because the BINs were delimited by a proprietary algorithm (RESL) that is applied to a mixture of public and private data. Here, we illustrate that many of the BINs described as species are unstable when the available public data are reanalyzed, reiterate that COI mostly measures time of divergence, and that BOLD Systems violates key principles of open science. We conclude by urging authors, reviewers, editors, and grantors to only publish and fund projects that adhere to modern standards of reproducibility.

DNA reconciles morphology and colouration in the drunk blenny genus Scartichthys (Teleostei: Blenniidae) and provides insights into their evolutionary history

The blenniids of the genus Scartichthys represent key herbivore species of central and south American Pacific coastal reefs. Yet Scartichthys spp. remain difficult to identify in the field, especially across the c.a 6000 km where three of the four currently accepted species are known to occur in sympatry. The main diagnostic characters from traditional taxonomy that have been used to revise this genus are indeed elusive. At the same time, species can display multiple colour patterns in the field, depending on the ontogenetic stage, habitat association, and/or reproductive behaviour. Overall, molecular characterization is warranted to help address these issues. Here, we used a combination of colouration, morphological and molecular data for the first time, including specimens representative of the four currently valid species and seven described colour patterns. Our integrative approach revealed that only three of the four species should be considered as valid; Scartichthys gigas (Steindachner, 1876), S. variolatus (Valenciennes, 1836) and S. viridis (Valenciennes, 1836); while S. crapulatus Williams 1990 should be synonymized with S. viridis. In the same way, our analyses show that one of the colour patterns attributed so far to S. gigas is characteristic of the juvenile stages of S. viridis. Our time-calibrated phylogeny shows that this genus is relatively young, with an estimated time of divergence between Scartichthys gigas and S. viridis of around 1.71 Ma. In comparison, the Desventuradas and Juan Fernandez Islands endemic S. variolatus diverged about 1.95 Ma. Our results help to clarify the taxonomy of the Scartichthys genus.

The new Coronavirus (SARS-CoV-2) in Central America: Demographic-spatial simulations, Analyses of Molecular Variance (AMOVA) and Neutrality Tests in complete genomes from Belize, Guatemala, Cuba, Jamaica and Puerto Rico

In this work, we evaluated the levels of genetic diversity in 38 complete genomes of SARS-CoV-2 from five Central American countries (Belize, Guatemala, Cuba, Jamaica and Puerto Rico) with 04, 10, 2, 8 and 14 haplotypes, respectively, with an extension of up to 29,885 bp. All sequences were publicly available on the National Biotechnology Information Center (NCBI) platform. Using specific methodologies for paired FST, AMOVA, mismatch, demographic-spatial expansion, molecular diversity and for the time of evolutionary divergence, it was possible to notice that only 79 sites remained conserved and that the high number of polymorphisms found helped to establish a clear pattern of genetic non-structuring, based on the time of divergence between the groups. The analyses also showed that significant evolutionary divergences within and between the five countries corroborate the fact that possible rapid and silent mutations are responsible for the increase in genetic variability of the Virus, a fact that would hinder the work with molecular targets for vaccines and medications in general.

SARS-CoV-2 in Brazil: analysis of molecular variance and genetic diversity in viral haplotypes found in the states of Rio de Janeiro, São Paulo, Paraná and Tocantins

In this work, 18 sequences of the SARS-CoV-2 virus were used, from four Brazilian states (Rio de Janeiro, São Paulo, Paraná and Tocantins) with 09, 04, 04, 8 and 01 haplotypes, respectively, with lengths ranging from 234 to 29,903 bp. All sequences were publicly available on the National Biotechnology Information Center (NCBI) platform and were previously aligned with the MEGA X software, where all gaps and ambiguous sites were extracted for the construction of the phylogenetic tree. Of the 301 sites analyzed, 68% varied, 131 of which were parsimonium-informative sites. Phylogenetic analyses revealed the presence of two distinct subgroups, corroborated by the high FST (80%). The high degree of polymorphism found among these samples helped to establish a clear pattern of non-genetic structuring, based on the time of divergence between the groups. All molecular variance estimators confirmed that there was no consensus in the conservation of the studied sequences, also indicating a high variation for the protein products of the virus. In a highly miscegenational and diverse population such as the Brazilian population, this observation draws our attention to the need for an urgent increase in public health actions, awareness strategies, hygiene and distancing practices and not the other way around.

Defining intraspecific conservation units in the endemic Cuban Rock Iguanas (Cyclura nubila nubila)

Defining conservation units is an important step in species management and requires interpretation of the genetic diversity and ecological function of the taxon being considered. We used the endemic Cuban Rock Iguanas (Cyclura nubila nubila) as a model to highlight this challenge and examined patterns of its intraspecific genetic diversity across Cuba. We evaluated nuclear (microsatellite loci) and mitochondrial diversity across eight populations from the island and its off-shore cays, and applied the population genetics results for assignment of Management Unit (MU) status and Evolutionary Significant Units (ESUs) based on phylogeographic and time of divergence information. We identified at least six distinct Cuban Rock Iguana MUs, encompassing demographically isolated and genetically differentiated populations across Cuba, most with low effective population size, declining populations, and with high risk of inbreeding and genetic drift. Hence, each MU should be considered of urgent conservation priority. Given the key ecological seed dispersal role of C. n. nubila, the disappearance of any MU could trigger the loss of local ecological functional diversity and major negative impacts on their ecosystems. Two divergent ESUs were also identified, exhibiting an historical east–west geographic separation on Cuba. Based on a Caribbean phylogeographic assessment, our findings strengthen the conclusion that all geographically and evolutionarily differentiated Cyclura species and subspecies across the archipelago warrant ESU distinction.

The genetic structure of Pristimantis latro (Anura: Craugastoridae) mirrors traits of their life history

One of the main hypotheses to explain the origin of Amazonian diversity is the barrier effect of the rivers known as the riverine-barrier hypothesis, which suggests that riverine barriers isolated once continuous populations leading to differentiation and speciation. In this context, we studied the genetic structure of Pristimantis latro, a newly described species that inhabits a region under marked anthropic pressure due to expansive livestock, illegal mining, and hydroelectric dam construction. The DNA was extracted from 52 P. latro individuals and then amplified via polymerase chain reaction (PCR) using the mitochondrial 16S rRNA and COI markers. To infer the time of divergence between the P. latro localities, we built a species tree and performed an analysis of molecular variance (AMOVA) to infer the genetic differentiation between and within the P. latro populations. We found that P. latro has a marked genetic structure in the populations of the right and left margins of the Xingu River and within the Tapajós-Xingu and Xingu-Tocantins interfluvial regions and that the time of divergence between the populations of the East and West banks of the Xingu River occurred approximately 380,000 years ago. This pattern of genetic structure corresponds to that reported in recent articles for the Pristimantis genus evidencing that species without tadpoles exhibit a genetic structure explained by the hypothesis of rivers as barriers.

A re-evaluation of the Chaetothyriales using criteria of comparative biology

Chaetothyriales is an ascomycetous order within Eurotiomycetes. The order is particularly known through the black yeasts and filamentous relatives that cause opportunistic infections in humans. All species in the order are consistently melanized. Ecology and habitats of species are highly diverse, and often rather extreme in terms of exposition and toxicity. Families are defined on the basis of evolutionary history, which is reconstructed by time of divergence and concepts of comparative biology using stochastical character mapping and a multi-rate Brownian motion model to reconstruct ecological ancestral character states. Ancestry is hypothesized to be with a rock-inhabiting life style. Ecological disparity increased significantly in late Jurassic, probably due to expansion of cytochromes followed by colonization of vacant ecospaces. Dramatic diversification took place subsequently, but at a low level of innovation resulting in strong niche conservatism for extant taxa. Families are ecologically different in degrees of specialization. One of the clades has adapted ant domatia, which are rich in hydrocarbons. In derived families, similar processes have enabled survival in domesticated environments rich in creosote and toxic hydrocarbons, and this ability might also explain the pronounced infectious ability of vertebrate hosts observed in these families. Conventional systems of morphological classification poorly correspond with recent phylogenetic data. Species are hypothesized to have low competitive ability against neighboring microbes, which interferes with their laboratory isolation on routine media. The dataset is unbalanced in that a large part of the extant biodiversity has not been analyzed by molecular methods, novel taxonomic entities being introduced at a regular pace. Our study comprises all available species sequenced to date for LSU and ITS, and a nomenclatural overview is provided. A limited number of species could not be assigned to any extant family.

Alfred’s Chronicle and the First Continuations

This chapter considers the vernacular chronicle produced at the court of King Alfred, its story, and its late-ninth-century evolution. It argues that this story was both dynastic history and a wider tale of English Christian history. It argues that seeing this chronicle as connected to the court rather than as deliberate royal propaganda solves some long-standing historical debates. Using the evidence of language and a comparative method involving Asser, surviving chronicles, and twelfth-century texts, it suggests that this chronicle was already an evolving text before 900. It questions the idea of deliberate circulation in the early 890s, suggesting an alternative model of copies made at different points. The early 890s were, nonetheless, a significant time of divergence and the beginning of the story of the separate development of vernacular chronicles.

Measuring Historical and Compositional Signals in Phylogenetic Data

Most commonly-used molecular phylogenetic methods assume that the sequences evolved on a single bifurcating tree and that the evolutionary processes operating at the variable sites are Markovian. Typically, it is also assumed that these evolutionary processes were stationary, reversible and homogenous across the edges of the tree and that the multiple substitutions at variable sites occurred so infrequently that the historical signal (i.e., the signal in DNA that is due to the order and time of divergence event) in phylogenetic data has been retained, allowing for accurate phylogenetic estimates to be obtained from the data. Here, we present two metrics, λ and δCFS, to quantify the strength of the historical and compositional signals in phylogenetic data. λ quantifies loss of historical signal, with λ = 0.0 indicating evidence of a strong historical signal and λ = 1.0 indicating evidence of a fully eroded historical signal. δCFS quantifies compositional distance from full symmetry of a divergence matrix generated by comparing two sequences, with δCFS = 0.0 indicating no evidence of evolution under dissimilar conditions and δCFS > 0.0 indicating increasing evidence of lineages diverging under different conditions. The metrics are implemented in methods intended for use after multiple sequence alignment and before model selection and phylogenetic analysis. Results generated using these methods allow users of phylogenetic tools to select phylogenetic data more wisely than it previously was possible. The merits of these metrics and methods are illustrated using simulated data and multi-gene alignments obtained from 144 insect genomes.