Inferring confidence sets of possibly misspecified gene trees

Phylogenomics and biogeography of sawflies and woodwasps (Hymenoptera, Symphyta)

Phylogenomic approaches have recently helped elucidate various insect relationships, but large-scale comprehensive analyses on relationships within sawflies and woodwasps are still lacking. Here, we infer the relationships and long-term biogeographic history of these hymenopteran groups using a large dataset of 354 UCE loci collected from 385 species that represent all major lineages. Early Hymenoptera started diversifying during the Early Triassic ∼249 Ma and spread all over the ancient supercontinent Pangaea. We recovered Xyeloidea as a monophyletic sister group to other Hymenoptera and Pamphilioidea as sister to Unicalcarida. Within the diverse family Tenthredinidae, our taxonomically and geographically expanded taxon sampling highlights the non-monophyly of several traditionally defined subfamilies. In addition, the recent removal of Athalia and related genera from the Tenthredinidae into the separate family Athaliidae is supported. The deep historical biogeography of the group is characterised by independent dispersals and re-colonisations between the northern (Laurasia) and southern (Gondwana) palaeocontinents. The breakup of these landmasses led to ancient vicariance in several Gondwanan lineages, while interchange across the Northern Hemisphere has continued until the Recent. The little-studied African sawfly fauna is likewise a diverse mixture of groups with varying routes of colonization. Our results reveal interesting parallels in the evolution and biogeography of early hymenopterans and other ancient insect groups.

Evolutionary origin and population diversity of a cryptic hybrid pathogen

Cryptic fungal pathogens pose disease management challenges due to their morphological resemblance to known pathogens. Here, we investigated the genomes and phenotypes of 53 globally distributed isolates of Aspergillus section Nidulantes fungi and found 30 clinical isolates-including four isolated from COVID-19 patients-were A. latus, a cryptic pathogen that originated via allodiploid hybridization. Notably, all A. latus isolates were misidentified. A. latus hybrids likely originated via a single hybridization event during the Miocene and harbor substantial genetic diversity. Transcriptome profiling of a clinical isolate revealed that both parental subgenomes are actively expressed and respond to environmental stimuli. Characterizing infection-relevant traits-such as drug resistance and growth under oxidative stress-revealed distinct phenotypic profiles among A. latus hybrids compared to parental and closely related species. Moreover, we identified four features that could aid A. latus taxonomic identification. Together, these findings deepen our understanding of the origin of cryptic pathogens.

A molecular phylogeny for all 21 families within Chiroptera (bats)

Bats, members of the Chiroptera order, rank as the second most diverse group among mammals. Recent molecular systematic studies on bats have successfully classified 21 families within two suborders: Yinpterochiroptera and Yangochiroptera. Nevertheless, the phylogeny within these 21 families has remained a subject of controversy. In this study, we have employed a balanced approach to establish a robust family-level phylogenetic hypothesis for bats, utilizing a more comprehensive molecular dataset. This dataset includes representative species from all 21 bat families, resulting in a reduced level of missing genetic information. The resulting phylogenetic tree comprises 21 lineages that are strongly supported, each corresponding to one of the bat families. Our findings support to place the Emballonuroidea superfamily as the basal lineage of Yangochiroptera, and that Myzopodidae should be situated as a basal lineage of Emballonuroidea, forming a sister relationship with the clade consisting of Nycteridae and Emballonuridae. Finally, we have conducted dating analyses on this newly resolved phylogenetic tree, providing divergence times for each bat family. Collectively, our study has employed a relatively comprehensive molecular dataset to establish a more robust phylogeny encompassing all 21 bat families. This improved phylogenetic framework will significantly contribute to our understanding of evolutionary processes, ecological roles, disease dynamics, and biodiversity conservation in the realm of bats.

The last of their kind: Is the genus Scutiger (Anura: Megophryidae) a relict element of the paleo-Transhimalaya biota?

The orographic evolution of the Himalaya-Tibet Mountain system continues to be a subject of controversy, leading to considerable uncertainty regarding the environment and surface elevation of the Tibetan Plateau during the Cenozoic era. As many geoscientific (but not paleontological) studies suggest, elevations close to modern heights exist in vast areas of Tibet since at least the late Paleogene, implicating the presence of large-scale alpine environments for more than 30 million years. To explore a recently proposed alternative model that assumes a warm temperate environment across paleo-Tibet, we carried out a phylogeographic survey using genomic analyses of samples covering the range of endemic lazy toads (Scutiger) across the Himalaya-Tibet orogen. We identified two main clades, with several, geographically distinct subclades. The long temporal gap between the stem and crown age of Scutiger may suggest high extinction rates. Diversification within the crown group, depending on the calibration, occurred either from the Mid-Miocene or Late-Miocene and continued until the Holocene. The present-day Himalayan Scutiger fauna could have evolved from lineages that existed on the southern edges of the paleo-Tibetan area (the Transhimalaya = Gangdese Shan), while extant species living on the eastern edge of the Plateau originated probably from the eastern edges of northern parts of the ancestral Tibetan area (Hoh Xil, Tanggula Shan). Based on the Mid-Miocene divergence time estimation and ancestral area reconstruction, we propose that uplift-associated aridification of a warm temperate Miocene-Tibet, coupled with high extirpation rates of ancestral populations, and species range shifts along drainage systems and epigenetic transverse valleys of the rising mountains, is a plausible scenario explaining the phylogenetic structure of Scutiger. This hypothesis aligns with the fossil record but conflicts with geoscientific concepts of high elevated Tibetan Plateau since the late Paleogene. Considering a Late-Miocene/Pliocene divergence time, an alternative scenario of dispersal from SE Asia into the East, Central, and West Himalaya cannot be excluded, although essential evolutionary and biogeographic aspects remain unresolved within this model.

Exploring Paleogene Tibet's warm temperate environments through target enrichment and phylogenetic niche modelling of Himalayan spiny frogs (Paini, Dicroglossidae)

The Cenozoic topographic development of the Himalaya-Tibet orogen (HTO) substantially affected the paleoenvironment and biodiversity patterns of High Asia. However, concepts on the evolution and paleoenvironmental history of the HTO differ massively in timing, elevational increase and sequence of surface uplift of the different elements of the orogen. Using target enrichment of a large set of transcriptome-derived markers, ancestral range estimation and paleoclimatic niche modelling, we assess a recently proposed concept of a warm temperate paleo-Tibet in Asian spiny frogs of the tribe Paini and reconstruct their historical biogeography. That concept was previously developed in invertebrates. Because of their early evolutionary origin, low dispersal capacity, high degree of local endemism, and strict dependence on temperature and humidity, the cladogenesis of spiny frogs may echo the evolution of the HTO paleoenvironment. We show that diversification of main lineages occurred during the early to Mid-Miocene, while the evolution of alpine taxa started during the late Miocene/early Pliocene. Our distribution and niche modelling results indicate range shifts and niche stability that may explain the modern disjunct distributions of spiny frogs. They probably maintained their (sub)tropical or (warm)temperate preferences and moved out of the ancestral paleo-Tibetan area into the Himalaya as the climate shifted, as opposed to adapting in situ. Based on ancestral range estimation, we assume the existence of low-elevation, climatically suitable corridors across paleo-Tibet during the Miocene along the Kunlun, Qiangtang and/or Gangdese Shan. Our results contribute to a deeper understanding of the mechanisms and processes of faunal evolution in the HTO.

Systematic revision of the South American "Nuncia" (Opiliones, Laniatores, Triaenonychidae)

The genus Nuncia has long been the most speciose within the Opiliones family Triaenonychidae, comprising 63 species and subspecies distributed across New Zealand and South America. Recent molecular studies utilizing Sanger sequencing and ultraconserved elements (UCEs) have indicated that this genus is not monophyletic, and true Nuncia are actually confined to New Zealand. Here, the morphology of all South American triaenonychids is re-examined and DNA sequence data compiled from three markers (18S rRNA, 28S rRNA and cytochrome c oxidase subunit I) for a large number of triaenonychid species, including specimens from all areas with species currently and formerly classified in Nuncia to reassess their phylogenetic position. Based on our findings we 1) revalidate the genus Chilenuncia (Muñoz-Cuevas, 1971) nom. rest.; 2) describe five new genera: Fresiax gen. nov., Mistralia gen. nov., Laftrachia gen. nov., Lautaria gen. nov., Nerudiella gen. nov.; 3) redescribe five species: Fresiaxspinulosa comb. nov., Mistraliaverrucosa comb. nov., Chilenunciachilensis comb. nov., Chilenunciarostrata comb. nov., Nerudiellaamericana comb. nov.; and 4) describe 22 new species of South American triaenonychids: Fresiaxconica sp. nov., Fresiaxfray sp. nov., Fresiaxmauryi sp. nov., Fresiaxpichicuy sp. nov., Mistraliaramirezi sp. nov., Laftrachiarobin sp. nov., Lautariaceachei sp. nov., Nerudiellacachai sp. nov., Nerudiellacaramavida sp. nov., Nerudiellacautin sp. nov., Nerudiellachoapa sp. nov., Nerudiellacuri sp. nov., Nerudiellagoroi sp. nov., Nerudiellajaimei sp. nov., Nerudiellamalleco sp. nov., Nerudiellapenco sp. nov., Nerudiellapichi sp. nov., Nerudiellaportai sp. nov., Nerudiellaquenes sp. nov., Nerudiellavilches sp. nov., Nerudiellawekufe sp. nov., and Nerudiellazapallar sp. nov. Furthermore, we provide detailed illustrations of all the South American species belonging to these lineages formerly classified in Nuncia.

Virus ecology and 7-year temporal dynamics across a permafrost thaw gradient

Soil microorganisms are pivotal in the global carbon cycle, but the viruses that affect them and their impact on ecosystems are less understood. In this study, we explored the diversity, dynamics, and ecology of soil viruses through 379 metagenomes collected annually from 2010 to 2017. These samples spanned the seasonally thawed active layer of a permafrost thaw gradient, which included palsa, bog, and fen habitats. We identified 5051 virus operational taxonomic units (vOTUs), doubling the known viruses for this site. These vOTUs were largely ephemeral within habitats, suggesting a turnover at the vOTU level from year to year. While the diversity varied by thaw stage and depth-related patterns were specific to each habitat, the virus communities did not significantly change over time. The abundance ratios of virus to host at the phylum level did not show consistent trends across the thaw gradient, depth, or time. To assess potential ecosystem impacts, we predicted hosts in silico and found viruses linked to microbial lineages involved in the carbon cycle, such as methanotrophy and methanogenesis. This included the identification of viruses of Candidatus Methanoflorens, a significant global methane contributor. We also detected a variety of potential auxiliary metabolic genes, including 24 carbon-degrading glycoside hydrolases, six of which are uniquely terrestrial. In conclusion, these long-term observations enhance our understanding of soil viruses in the context of climate-relevant processes and provide opportunities to explore their role in terrestrial carbon cycling.

Evolutionary and phylogenetic insights from the mitochondrial genomic analysis of Diceraeus melacanthus and D. furcatus (Hemiptera: Pentatomidae)

The mitochondrial genomes of D. melacanthus and D. furcatus were sequenced and used to investigate the phylogenetic relationships with 54 species of Pentatomidae. Their mitogenomes are 17,197 and 15,444 bp-long, respectively, including 13 protein-coding genes (PCGs), 2 ribosomal RNA genes, and 22/21 transfer RNA genes, with conserved gene arrangement. Leu, Lys, and Ser were the most common amino acids in their PCGs. PCGs evolutionary analysis indicated their mitogenomes are under purifying selection, and the most conserved genes are from the cytochrome complex, reinforcing their suitability as markers for molecular taxonomy. We identified 490 mtSSRs in 56 Pentatomidae species, with large variation and a positive correlation between mtSSR number and genome size. Three mtSSRs were identified in each Diceraeus species. Only the mtSSR in the nad6 (D. melacanthus) and nad4 (D. furcatus) appear to have application as molecular markers for species characterization. Phylogenetic analysis confirmed the monophyly of Pentatomidae. However, our analysis challenged the monophyly of Pentatominae and Podopinae. We also detected unexpected relationships among some tribes and genera, highlighting the complexity of the internal taxonomic structure of Pentatomidae. Both Diceraeus species were grouped in the same clade with the remaining Carpocorini analyzed.

Genome-wide association identifies a BAHD acyltransferase activity that assembles an ester of glucuronosylglycerol and phenylacetic acid

Genome-wide association studies (GWAS) are an effective approach to identify new specialized metabolites and the genes involved in their biosynthesis and regulation. In this study, GWAS of Arabidopsis thaliana soluble leaf and stem metabolites identified alleles of an uncharacterized BAHD-family acyltransferase (AT5G57840) associated with natural variation in three structurally related metabolites. These metabolites were esters of glucuronosylglycerol, with one metabolite containing phenylacetic acid as the acyl component of the ester. Knockout and overexpression of AT5G57840 in Arabidopsis and heterologous overexpression in Nicotiana benthamiana and Escherichia coli demonstrated that it is capable of utilizing phenylacetyl-CoA as an acyl donor and glucuronosylglycerol as an acyl acceptor. We, thus, named the protein Glucuronosylglycerol Ester Synthase (GGES). Additionally, phenylacetyl glucuronosylglycerol increased in Arabidopsis CYP79A2 mutants that overproduce phenylacetic acid and was lost in knockout mutants of UDP-sulfoquinovosyl: diacylglycerol sulfoquinovosyl transferase, an enzyme required for glucuronosylglycerol biosynthesis and associated with glycerolipid metabolism under phosphate-starvation stress. GGES is a member of a well-supported clade of BAHD family acyltransferases that arose by duplication and neofunctionalized during the evolution of the Brassicales within a larger clade that includes HCT as well as enzymes that synthesize other plant-specialized metabolites. Together, this work extends our understanding of the catalytic diversity of BAHD acyltransferases and uncovers a pathway that involves contributions from both phenylalanine and lipid metabolism.

Phylogenomic reconstruction of Solenogastres (Mollusca, Aplacophora) informs hypotheses on body size evolution

Body size is a fundamental characteristic of animals that impacts every aspect of their biology from anatomical complexity to ecology. In Mollusca, Solenogastres has been considered important to understanding the group's early evolution as most morphology-based phylogenetic reconstructions placed it as an early branching molluscan lineage. Under this scenario, molluscs were thought to have evolved from a small, turbellarian-like ancestor and small (i.e., macrofaunal) body size was inferred to be plesiomorphic for Solenogastres. More recently, phylogenomic studies have shown that aplacophorans (Solenogastres + Caudofoveata) form a clade with chitons (Polyplacophora), which is sister to all other molluscs, suggesting a relatively large-bodied (i.e., megafaunal) ancestor for Mollusca. Meanwhile, recent investigations into aplacophoran phylogeny have called the assumption that the last common ancestor of Solenogastres was small-bodied into question, but sampling of meiofaunal species was limited, biasing these studies towards large-bodied taxa and leaving fundamental questions about solenogaster body size evolution unanswered. Here, we supplemented available data with transcriptomes from eight diverse meiofaunal species of Solenogastres and conducted phylogenomic analyses on datasets of up to 949 genes. Maximum likelihood analyses support the meiofaunal family Meiomeniidae as the sister group to all other solenogasters, congruent with earlier ideas of a small-bodied ancestor of Solenogastres. In contrast, Bayesian Inference analyses support the large-bodied family Amphimeniidae as the sister group to all other solenogasters. Investigation of phylogenetic signal by comparing site-wise likelihood scores for the two competing hypotheses support the Meiomeniidae-first topology. In light of these results, we performed ancestral character state reconstruction to explore the implications of both hypotheses on understanding of Solenogaster evolution and review previous hypotheses about body size evolution and its potential consequences for solenogaster biology. Both hypotheses imply that body size evolution has been highly dynamic over the course of solenogaster evolution and that their relatively static body plan has successfully allowed for evolutionary transitions between meio-, macro- and megafaunal size ranges.

Redefining the treponemal history through pre-Columbian genomes from Brazil

The origins of treponemal diseases have long remained unknown, especially considering the sudden onset of the first syphilis epidemic in the late 15th century in Europe and its hypothesized arrival from the Americas with Columbus' expeditions1,2. Recently, ancient DNA evidence has revealed various treponemal infections circulating in early modern Europe and colonial-era Mexico3-6. However, there has been to our knowledge no genomic evidence of treponematosis recovered from either the Americas or the Old World that can be reliably dated to the time before the first trans-Atlantic contacts. Here, we present treponemal genomes from nearly 2,000-year-old human remains from Brazil. We reconstruct four ancient genomes of a prehistoric treponemal pathogen, most closely related to the bejel-causing agent Treponema pallidum endemicum. Contradicting the modern day geographical niche of bejel in the arid regions of the world, the results call into question the previous palaeopathological characterization of treponeme subspecies and showcase their adaptive potential. A high-coverage genome is used to improve molecular clock date estimations, placing the divergence of modern T. pallidum subspecies firmly in pre-Columbian times. Overall, our study demonstrates the opportunities within archaeogenetics to uncover key events in pathogen evolution and emergence, paving the way to new hypotheses on the origin and spread of treponematoses.

Ordovician origin and subsequent diversification of the brown algae

Brown algae are the only group of heterokont protists exhibiting complex multicellularity. Since their origin, brown algae have adapted to various marine habitats, evolving diverse thallus morphologies and gamete types. However, the evolutionary processes behind these transitions remain unclear due to a lack of a robust phylogenetic framework and problems with time estimation. To address these issues, we employed plastid genome data from 138 species, including heterokont algae, red algae, and other red-derived algae. Based on a robust phylogeny and new interpretations of algal fossils, we estimated the geological times for brown algal origin and diversification. The results reveal that brown algae first evolved true multicellularity, with plasmodesmata and reproductive cell differentiation, during the late Ordovician Period (ca. 450 Ma), coinciding with a major diversification of marine fauna (the Great Ordovician Biodiversification Event) and a proliferation of multicellular green algae. Despite its early Paleozoic origin, the diversification of major orders within this brown algal clade accelerated only during the Mesozoic Era, coincident with both Pangea rifting and the diversification of other heterokont algae (e.g., diatoms), coccolithophores, and dinoflagellates, with their red algal-derived plastids. The transition from ancestral isogamy to oogamy was followed by three simultaneous reappearances of isogamy during the Cretaceous Period. These are concordant with a positive character correlation between parthenogenesis and isogamy. Our new brown algal timeline, combined with a knowledge of past environmental conditions, shed new light on brown algal diversification and the intertwined evolution of multicellularity and sexual reproduction.

Phylogenomics of the psychoactive mushroom genus Psilocybe and evolution of the psilocybin biosynthetic gene cluster

Psychoactive mushrooms in the genus Psilocybe have immense cultural value and have been used for centuries in Mesoamerica. Despite the recent surge of interest in these mushrooms due to the psychotherapeutic potential of their natural alkaloid psilocybin, their phylogeny and taxonomy remain substantially incomplete. Moreover, the recent elucidation of the psilocybin biosynthetic gene cluster is known for only five of ~165 species of Psilocybe, four of which belong to only one of two major clades. We set out to improve the phylogeny of Psilocybe using shotgun sequencing of fungarium specimens, from which we obtained 71 metagenomes including from 23 types, and conducting phylogenomic analysis of 2,983 single-copy gene families to generate a fully supported phylogeny. Molecular clock analysis suggests the stem lineage of Psilocybe arose ~67 mya and diversified ~56 mya. We also show that psilocybin biosynthesis first arose in Psilocybe, with 4 to 5 possible horizontal transfers to other mushrooms between 40 and 9 mya. Moreover, predicted orthologs of the psilocybin biosynthetic genes revealed two distinct gene orders within the biosynthetic gene cluster that corresponds to a deep split within the genus, possibly a signature of two independent acquisitions of the cluster within Psilocybe.

A Guide to Phylogenomic Inference

Phylogenomics aims at reconstructing the evolutionary histories of organisms taking into account whole genomes or large fractions of genomes. Phylogenomics has significant applications in fields such as evolutionary biology, systematics, comparative genomics, and conservation genetics, providing valuable insights into the origins and relationships of species and contributing to our understanding of biological diversity and evolution. This chapter surveys phylogenetic concepts and methods aimed at both gene tree and species tree reconstruction while also addressing common pitfalls, providing references to relevant computer programs. A practical phylogenomic analysis example including bacterial genomes is presented at the end of the chapter.

Mwhitiwhiti Aotearoa: Phylogeny and synonymy of the silent alpine grasshopper radiation of New Zealand (Orthoptera: Acrididae)

Aotearoa New Zealand has a fauna of endemic alpine grasshoppers, consisting of thirteen species distributed among four genera. The many re-classifications of species within this group and the presence of species complexes highlight the uncertainty that surrounds relationships within and between these genera. High-throughput Next Generation Sequencing was used to assemble the complete mitochondrial genomes, 45S ribosomal cassettes and histone sequences of New Zealands four endemic alpine genera: Alpinacris, Brachaspis, Paprides and Sigaus. Phylogenetic analysis of these molecular datasets, as individual genes, partitions and combinations returned a consistent topology that is incompatible with the current classification. The genera Sigaus, Alpinacris, and Paprides all exhibit paraphyly. A consideration of the pronotum, epiphallus and terminalia of adult specimens reveals species-specific differences, but fails to provide compelling evidence for species groups justifying distinct genera. In combination with phylogenetic, morphological and spatial evidence we propose a simplified taxonomy consisting of a single genus for the mwhitiwhiti Aotearoa species radiation.

Bacteria can maintain rRNA operons solely on plasmids for hundreds of millions of years

It is generally assumed that all bacteria must have at least one rRNA operon (rrn operon) on the chromosome, but some strains of the genera Aureimonas and Oecophyllibacter carry their sole rrn operon on a plasmid. However, other related strains and species have chromosomal rrn loci, suggesting that the exclusive presence of rrn operons on a plasmid is rare and unlikely to be stably maintained over long evolutionary periods. Here, we report the results of a systematic search for additional bacteria without chromosomal rrn operons. We find that at least four bacterial clades in the phyla Bacteroidota, Spirochaetota, and Pseudomonadota (Proteobacteria) lost chromosomal rrn operons independently. Remarkably, Persicobacteraceae have apparently maintained this peculiar genome organization for hundreds of millions of years. In our study, all the rrn-carrying plasmids in bacteria lacking chromosomal rrn loci possess replication initiator genes of the Rep_3 family. Furthermore, the lack of chromosomal rrn operons is associated with differences in copy numbers of rrn operons, plasmids, and chromosomal tRNA genes. Thus, our findings indicate that the absence of rrn loci in bacterial chromosomes can be stably maintained over long evolutionary periods.

Phylogenetic and taxonomic updates of Agaricales, with an emphasis on Tricholomopsis

The order Agaricales was divided into eight suborders. However, the phylogenetic relationships among some suborders are largely unresolved, and the phylogenetic positions and delimitations of some taxa, such as Sarcomyxaceae and Tricholomopsis, remain unsettled. In this study, sequence data of 38 genomes were generated through genome skimming on an Illumina sequencing system. To anchor the systematic position of Sarcomyxaceae and Tricholomopsis, a phylogenetic analysis based on 555 single-copy orthologous genes from the aforementioned genomes and 126 publicly accessible genomes was performed. The results fully supported the clustering of Tricholomopsis with Phyllotopsis and Pleurocybella within Phyllotopsidaceae, which formed a divergent monophyletic major lineage together with Pterulaceae, Radulomycetaceae, and Macrotyphula in Agaricales. The analysis also revealed that Sarcomyxaceae formed a unique major clade. Therefore, two new suborders, Phyllotopsidineae and Sarcomyxineae, are proposed for the two major lineages. Analyses of 450 single-copy orthologous genes and four loci suggested that Tricholomopsis consisted of at least four clades. Tricholomopsis is subsequently subdivided into four distinct sections. Seventeen Tricholomopsis species in China, including six new species, are reported. Conoloma is established to accommodate T. mucronata. The substrate preference of Tricholomopsis species and the transitions of the pileate ornamentations among the species within the genus are discussed.

The Himalayan uplift and evolution of aquatic biodiversity across Asia: Snowtrout (Cyprininae: Schizothorax) as a test case

Global biodiversity hotspots are often remote, tectonically active areas undergoing climatic fluctuations, such as the Himalaya Mountains and neighboring Qinghai-Tibetan Plateau (QTP). They provide biogeographic templates upon which endemic biodiversity can be mapped to infer diversification scenarios. Yet, this process can be somewhat opaque for the Himalaya, given substantial data gaps separating eastern and western regions. To help clarify, we evaluated phylogeographic and phylogenetic hypotheses for a widespread fish (Snowtrout: Cyprininae; Schizothorax) by sequencing 1,140 base pair of mtDNA cytochrome-b (cytb) from Central Himalaya samples (Nepal: N = 53; Bhutan: N = 19), augmented with 68 GenBank sequences (N = 60 Schizothorax/N = 8 outgroups). Genealogical relationships (N = 132) were analyzed via maximum likelihood (ML), Bayesian (BA), and haplotype network clustering, with clade divergence estimated via TimeTree. Snowtrout seemingly originated in Central Asia, dispersed across the QTP, then into Bhutan via southward-flowing tributaries of the east-flowing Yarlung-Tsangpo River (YLTR). Headwaters of five large Asian rivers provided dispersal corridors from Central into eastern/southeastern Asia. South of the Himalaya, the YLTR transitions into the Brahmaputra River, facilitating successive westward colonization of Himalayan drainages first in Bhutan, then Nepal, followed by far-western drainages subsequently captured by the (now) westward-flowing Indus River. Two distinct Bhutanese phylogenetic groups were recovered: Bhutan-1 (with three subclades) seemingly represents southward dispersal from the QTP; Bhutan-2 apparently illustrates northward colonization from the Lower Brahmaputra. The close phylogenetic/phylogeographic relationships between the Indus River (Pakistan) and western tributaries of the Upper Ganges (India/Nepal) potentially implicate an historic, now disjunct connection. Greater species-divergences occurred across rather than within-basins, suggesting vicariance as a driver. The Himalaya is a component of the Earth's largest glacial reservoir (i.e., the "third-pole") separate from the Arctic/Antarctic. Its unique aquatic biodiversity must be defined and conserved through broad, trans-national collaborations. Our study provides an initial baseline for this process.

The complete chloroplast genome of Diplodiscus trichospermus and phylogenetic position of Brownlowioideae within Malvaceae

BACKGROUND

Malvaceae is an economically important plant family of 4,225 species in nine subfamilies. Phylogenetic relationships among the nine subfamilies have always been controversial, especially for Brownlowioideae, whose phylogenetic position remains largely unknown due to the lack of samples in previous analysis datasets. To greatly clarify the phylogenetic relationship of Malvaceae, we newly sequenced and assembled the plastome of Diplodiscus trichospermus taxonomically located in Brownlowioideae, and downloaded the allied genomes from public database to build a dataset covering all subfamily members of Malvaceae.

RESULTS

The annotation results showed that the plastome of Diplodiscus trichospermus has a typical quadripartite structure, comprising 112 unique genes, namely 78 protein-coding genes, 30 tRNA genes and 4 rRNA genes. The total length was 158,570 bp with 37.2% GC content. Based on the maximum likelihood method and Bayesian inference, a robust phylogenetic backbone of Malvaceae was reconstructed. The topology showed that Malvaceae was divided distinctly into two major branches which were previously recognized as Byttneriina and Malvadendrina. In the Malvadendrina clade, Malvoideae and Bombacoideae formed, as always, a close sister clade named as Malvatheca. Subfamily Helicteroideae occupied the most basal position and was followed by Sterculioideae which was sister to the alliance of Malvatheca, Brownlowioideae, Dombeyoideae, and Tilioideae. Brownlowioideae together with the clade comprising Dombeyoideae and Tilioideae formed a sister clade to Malvatheca. In addition, one specific conservation SSR and three specific palindrome sequences were observed in Brownlowioideae.

CONCLUSIONS

In this study, the phylogenetic framework of subfamilies in Malvaceae has been resolved clearly based on plastomes, which may contribute to a better understanding of the classification and plastome evolution for Malvaceae.

The Free Lunch is not over yet-systematic exploration of numerical thresholds in maximum likelihood phylogenetic inference

Summary

Maximum likelihood (ML) is a widely used phylogenetic inference method. ML implementations heavily rely on numerical optimization routines that use internal numerical thresholds to determine convergence. We systematically analyze the impact of these threshold settings on the log-likelihood and runtimes for ML tree inferences with RAxML-NG, IQ-TREE, and FastTree on empirical datasets. We provide empirical evidence that we can substantially accelerate tree inferences with RAxML-NG and IQ-TREE by changing the default values of two such numerical thresholds. At the same time, altering these settings does not significantly impact the quality of the inferred trees. We further show that increasing both thresholds accelerates the RAxML-NG bootstrap without influencing the resulting support values. For RAxML-NG, increasing the likelihood thresholds ϵ LnL and ϵ brlen to 10 and 103, respectively, results in an average tree inference speedup of 1.9 ± 0.6 on Data collection 1, 1.8 ± 1.1 on Data collection 2, and 1.9 ± 0.8 on Data collection 2 for the RAxML-NG bootstrap compared to the runtime under the current default setting. Increasing the likelihood threshold ϵ LnL to 10 in IQ-TREE results in an average tree inference speedup of 1.3 ± 0.4 on Data collection 1 and 1.3 ± 0.9 on Data collection 2.

Availability and implementation

All MSAs we used for our analyses, as well as all results, are available for download at https://cme.h-its.org/exelixis/material/freeLunch_data.tar.gz. Our data generation scripts are available at https://github.com/tschuelia/ml-numerical-analysis.

Likelihood-Based Tests of Species Tree Hypotheses

Likelihood-based tests of phylogenetic trees are a foundation of modern systematics. Over the past decade, an enormous wealth and diversity of model-based approaches have been developed for phylogenetic inference of both gene trees and species trees. However, while many techniques exist for conducting formal likelihood-based tests of gene trees, such frameworks are comparatively underdeveloped and underutilized for testing species tree hypotheses. To date, widely used tests of tree topology are designed to assess the fit of classical models of molecular sequence data and individual gene trees and thus are not readily applicable to the problem of species tree inference. To address this issue, we derive several analogous likelihood-based approaches for testing topologies using modern species tree models and heuristic algorithms that use gene tree topologies as input for maximum likelihood estimation under the multispecies coalescent. For the purpose of comparing support for species trees, these tests leverage the statistical procedures of their original gene tree-based counterparts that have an extended history for testing phylogenetic hypotheses at a single locus. We discuss and demonstrate a number of applications, limitations, and important considerations of these tests using simulated and empirical phylogenomic data sets that include both bifurcating topologies and reticulate network models of species relationships. Finally, we introduce the open-source R package SpeciesTopoTestR (SpeciesTopology Tests in R) that includes a suite of functions for conducting formal likelihood-based tests of species topologies given a set of input gene tree topologies.

Evolutionary origin, population diversity, and diagnostics for a cryptic hybrid pathogen

Cryptic fungal pathogens pose significant identification and disease management challenges due to their morphological resemblance to known pathogenic species while harboring genetic and (often) infectionrelevant trait differences. The cryptic fungal pathogen Aspergillus latus, an allodiploid hybrid originating from Aspergillus spinulosporus and an unknown close relative of Aspergillus quadrilineatus within section Nidulantes, remains poorly understood. The absence of accurate diagnostics for A. latus has led to misidentifications, hindering epidemiological studies and the design of effective treatment plans. We conducted an in-depth investigation of the genomes and phenotypes of 44 globally distributed isolates (41 clinical isolates and three type strains) from Aspergillus section Nidulantes. We found that 21 clinical isolates were A. latus; notably, standard methods of pathogen identification misidentified all A. latus isolates. The remaining isolates were identified as A. spinulosporus (8), A. quadrilineatus (1), or A. nidulans (11). Phylogenomic analyses shed light on the origin of A. latus, indicating one or two hybridization events gave rise to the species during the Miocene, approximately 15.4 to 8.8 million years ago. Characterizing the A. latus pangenome uncovered substantial genetic diversity within gene families and biosynthetic gene clusters. Transcriptomic analysis revealed that both parental genomes are actively expressed in nearly equal proportions and respond to environmental stimuli. Further investigation into infection-relevant chemical and physiological traits, including drug resistance profiles, growth under oxidative stress conditions, and secondary metabolite biosynthesis, highlight distinct phenotypic profiles of the hybrid A. latus compared to its parental and closely related species. Leveraging our comprehensive genomic and phenotypic analyses, we propose five genomic and phenotypic markers as diagnostics for A. latus species identification. These findings provide valuable insights into the evolutionary origin, genomic outcome, and phenotypic implications of hybridization in a cryptic fungal pathogen, thus enhancing our understanding of the underlying processes contributing to fungal pathogenesis. Furthermore, our study underscores the effectiveness of extensive genomic and phenotypic analyses as a promising approach for developing diagnostics applicable to future investigations of cryptic and emerging pathogens.

Multiple and diversified transposon lineages contribute to early and recent bivalve genome evolution

BACKGROUND

Transposable elements (TEs) can represent one of the major sources of genomic variation across eukaryotes, providing novel raw materials for species diversification and innovation. While considerable effort has been made to study their evolutionary dynamics across multiple animal clades, molluscs represent a substantially understudied phylum. Here, we take advantage of the recent increase in mollusc genomic resources and adopt an automated TE annotation pipeline combined with a phylogenetic tree-based classification, as well as extensive manual curation efforts, to characterize TE repertories across 27 bivalve genomes with a particular emphasis on DDE/D class II elements, long interspersed nuclear elements (LINEs), and their evolutionary dynamics.

RESULTS

We found class I elements as highly dominant in bivalve genomes, with LINE elements, despite less represented in terms of copy number per genome, being the most common retroposon group covering up to 10% of their genome. We mined 86,488 reverse transcriptases (RVT) containing LINE coming from 12 clades distributed across all known superfamilies and 14,275 class II DDE/D-containing transposons coming from 16 distinct superfamilies. We uncovered a previously underestimated rich and diverse bivalve ancestral transposon complement that could be traced back to their most recent common ancestor that lived ~ 500 Mya. Moreover, we identified multiple instances of lineage-specific emergence and loss of different LINEs and DDE/D lineages with the interesting cases of CR1- Zenon, Proto2, RTE-X, and Academ elements that underwent a bivalve-specific amplification likely associated with their diversification. Finally, we found that this LINE diversity is maintained in extant species by an equally diverse set of long-living and potentially active elements, as suggested by their evolutionary history and transcription profiles in both male and female gonads.

CONCLUSIONS

We found that bivalves host an exceptional diversity of transposons compared to other molluscs. Their LINE complement could mainly follow a "stealth drivers" model of evolution where multiple and diversified families are able to survive and co-exist for a long period of time in the host genome, potentially shaping both recent and early phases of bivalve genome evolution and diversification. Overall, we provide not only the first comparative study of TE evolutionary dynamics in a large but understudied phylum such as Mollusca, but also a reference library for ORF-containing class II DDE/D and LINE elements, which represents an important genomic resource for their identification and characterization in novel genomes.

Human Anelloviruses: Influence of Demographic Factors, Recombination, and Worldwide Diversity

Anelloviruses represent the major and most diverse component of the healthy human virome, referred to as the anellome. In this study, we determined the anellome of 50 blood donors, forming two sex- and age-matched groups. Anelloviruses were detected in 86% of the donors. The number of detected anelloviruses increased with age and was approximately twice as high in men as in women. A total of 349 complete or nearly complete genomes were classified as belonging to torque teno virus (TTV), torque teno mini virus (TTMV), and torque teno midi virus (TTMDV) anellovirus genera (197, 88, and 64 sequences, respectively). Most donors had intergenus (69.8%) or intragenus (72.1%) coinfections. Despite the limited number of sequences, intradonor recombination analysis showed 6 intragenus recombination events in ORF1. As thousands of anellovirus sequences have been described recently, we finally analyzed the global diversity of human anelloviruses. Species richness and diversity were close to saturation in each anellovirus genus. Recombination was found to be the main factor promoting diversity, although its effect was significantly lower in TTV than in TTMV and TTMDV. Overall, our results suggest that differences in diversity between genera may be caused by variations in the relative contribution of recombination. IMPORTANCE Anelloviruses are the most common human infectious viruses and are considered essentially harmless. Compared to other human viruses, they are characterized by enormous diversity, and recombination is suggested to play an important role in their diversification and evolution. Here, by analyzing the composition of the plasma anellome of 50 blood donors, we find that recombination is also a determinant of viral evolution at the intradonor level. On a larger scale, analysis of anellovirus sequences currently available in databases shows that their diversity is close to saturation and differs among the three human anellovirus genera and that recombination is the main factor explaining this intergenus variability. Global characterization of anellovirus diversity could provide clues about possible associations between certain virus variants and pathologies, as well as facilitate the implementation of unbiased PCR-based detection protocols, which may be relevant for using anelloviruses as endogenous markers of immune status.

Statistical evaluation of character support reveals the instability of higher-level dinosaur phylogeny

The interrelationships of the three major dinosaur clades (Theropoda, Sauropodomorpha, and Ornithischia) have come under increased scrutiny following the recovery of conflicting phylogenies by a large new character matrix and its extensively modified revision. Here, we use tools derived from recent phylogenomic studies to investigate the strength and causes of this conflict. Using maximum likelihood as an overarching framework, we examine the global support for alternative hypotheses as well as the distribution of phylogenetic signal among individual characters in both the original and rescored dataset. We find the three possible ways of resolving the relationships among the main dinosaur lineages (Saurischia, Ornithischiformes, and Ornithoscelida) to be statistically indistinguishable and supported by nearly equal numbers of characters in both matrices. While the changes made to the revised matrix increased the mean phylogenetic signal of individual characters, this amplified rather than reduced their conflict, resulting in greater sensitivity to character removal or coding changes and little overall improvement in the ability to discriminate between alternative topologies. We conclude that early dinosaur relationships are unlikely to be resolved without fundamental changes to both the quality of available datasets and the techniques used to analyze them.

Identification of a covert evolutionary pathway between two protein folds

Although homologous protein sequences are expected to adopt similar structures, some amino acid substitutions can interconvert α-helices and β-sheets. Such fold switching may have occurred over evolutionary history, but supporting evidence has been limited by the: (1) abundance and diversity of sequenced genes, (2) quantity of experimentally determined protein structures, and (3) assumptions underlying the statistical methods used to infer homology. Here, we overcome these barriers by applying multiple statistical methods to a family of ~600,000 bacterial response regulator proteins. We find that their homologous DNA-binding subunits assume divergent structures: helix-turn-helix versus α-helix + β-sheet (winged helix). Phylogenetic analyses, ancestral sequence reconstruction, and AlphaFold2 models indicate that amino acid substitutions facilitated a switch from helix-turn-helix into winged helix. This structural transformation likely expanded DNA-binding specificity. Our approach uncovers an evolutionary pathway between two protein folds and provides a methodology to identify secondary structure switching in other protein families.

Bacterial NLR-related proteins protect against phage

Bacteria use a wide range of immune pathways to counter phage infection. A subset of these genes shares homology with components of eukaryotic immune systems, suggesting that eukaryotes horizontally acquired certain innate immune genes from bacteria. Here, we show that proteins containing a NACHT module, the central feature of the animal nucleotide-binding domain and leucine-rich repeat containing gene family (NLRs), are found in bacteria and defend against phages. NACHT proteins are widespread in bacteria, provide immunity against both DNA and RNA phages, and display the characteristic C-terminal sensor, central NACHT, and N-terminal effector modules. Some bacterial NACHT proteins have domain architectures similar to the human NLRs that are critical components of inflammasomes. Human disease-associated NLR mutations that cause stimulus-independent activation of the inflammasome also activate bacterial NACHT proteins, supporting a shared signaling mechanism. This work establishes that NACHT module-containing proteins are ancient mediators of innate immunity across the tree of life.

A novel aminotransferase gene and its regulator acquired in Saccharomyces by a horizontal gene transfer event

BACKGROUND

Horizontal gene transfer (HGT) is an evolutionary mechanism of adaptive importance, which has been deeply studied in wine S. cerevisiae strains, where those acquired genes conferred improved traits related to both transport and metabolism of the nutrients present in the grape must. However, little is known about HGT events that occurred in wild Saccharomyces yeasts and how they determine their phenotypes.

RESULTS

Through a comparative genomic approach among Saccharomyces species, we detected a subtelomeric segment present in the S. uvarum, S. kudriavzevii, and S. eubayanus species, belonging to the first species to diverge in the Saccharomyces genus, but absent in the other Saccharomyces species. The segment contains three genes, two of which were characterized, named DGD1 and DGD2. DGD1 encodes dialkylglicine decarboxylase, whose specific substrate is the non-proteinogenic amino acid 2-aminoisobutyric acid (AIB), a rare amino acid present in some antimicrobial peptides of fungal origin. DGD2 encodes putative zinc finger transcription factor, which is essential to induce the AIB-dependent expression of DGD1. Phylogenetic analysis showed that DGD1 and DGD2 are closely related to two adjacent genes present in Zygosaccharomyces.

CONCLUSIONS

The presented results show evidence of an early HGT event conferring new traits to the ancestor of the Saccharomyces genus that could be lost in the evolutionary more recent Saccharomyces species, perhaps due to loss of function during the colonization of new habitats.

Past, Present, and Future of Naturally Occurring Antimicrobials Related to Snake Venoms

This review focuses on proteins and peptides with antimicrobial activity because these biopolymers can be useful in the fight against infectious diseases and to overcome the critical problem of microbial resistance to antibiotics. In fact, snakes show the highest diversification among reptiles, surviving in various environments; their innate immunity is similar to mammals and the response of their plasma to bacteria and fungi has been explored mainly in ecological studies. Snake venoms are a rich source of components that have a variety of biological functions. Among them are proteins like lectins, metalloproteinases, serine proteinases, L-amino acid oxidases, phospholipases type A₂, cysteine-rich secretory proteins, as well as many oligopeptides, such as waprins, cardiotoxins, cathelicidins, and β-defensins. In vitro, these biomolecules were shown to be active against bacteria, fungi, parasites, and viruses that are pathogenic to humans. Not only cathelicidins, but all other proteins and oligopeptides from snake venom have been proteolyzed to provide short antimicrobial peptides, or for use as templates for developing a variety of short unnatural sequences based on their structures. In addition to organizing and discussing an expressive amount of information, this review also describes new β-defensin sequences of Sistrurus miliarius that can lead to novel peptide-based antimicrobial agents, using a multidisciplinary approach that includes sequence phylogeny.

Exploring Evolutionary Relationships within Neodermata Using Putative Orthologous Groups of Proteins, with Emphasis on Peptidases

The phylogenetic relationships within Neodermata were examined based on putative orthologous groups of proteins (OGPs) from 11 species of Monogenea, Trematoda, and Cestoda. The dataset included OGPs from BUSCO and OMA. Additionally, peptidases were identified and evaluated as phylogenetic markers. Phylogenies were inferred using the maximum likelihood method. A network analysis and a hierarchical grouping analysis of the principal components (HCPC) of orthologous groups of peptidases were performed. The phylogenetic analyses showed the monopisthocotylean monogeneans as the sister-group of cestodes, and the polyopisthocotylean monogeneans as the sister-group of trematodes. However, the sister-group relationship between Monopisthocotylea and Cestoda was not statistically well supported. The network analysis and HCPC also showed a cluster formed by polyopisthocotyleans and trematodes. The present study supports the non-monophyly of Monogenea. An analysis of mutation rates indicated that secreted peptidases and inhibitors, and those with multiple copies, are under positive selection pressure, which could explain the expansion of some families such as C01, C19, I02, and S01. Whilst not definitive, our study presents another point of view in the discussion of the evolution of Neodermata, and we hope that our data drive further discussion and debate on this intriguing topic.

Unveiling the evolutionary relationships and the high cryptic diversity in Andean rainfrogs (Craugastoridae: Pristimantis myersi group)

Background

Pristimantis is the most diverse genus of terrestrial frogs. Historically, it has been divided into several phenetic groups in order to facilitate species identification. However, in light of phylogenetic analysis, many of these groups have been shown to be non-monophyletic, denoting a high degree of morphological convergence and limited number of diagnostic traits. In this study, we focus on the Pristimantis myersi group, an assemblage of small rainfrogs distributed throughout the Andes of Ecuador and Colombia, whose external morphology is highly conserved, and its species diversity and evolutionary relationships largely unknown.

Methods

We inferred a new phylogenetic hypothesis for the frog genus Pristimantis, including all available sequences of the mtDNA 16S rRNA, as well as new DNA sequences from 175 specimens. Our sampling included 19 of the 24 species currently recognized as part of the Pristimantis myersi group.

Results

Our new evolutionary hypothesis recovered the P. myersi group as non-monophyletic and composed of 16 species. Therefore, we exclude P. albujai, P. bicantus, P. sambalan, and P. nelsongalloi in order to preserve the monophyly of the group. We discovered at least eight candidate species, most of them hidden under the names of P. leoni, P. hectus, P. festae, P. gladiator, and P. ocreatus.

Discussion

Our results reveal the occurrence of a high level of cryptic diversity to the species level within the P. myersi group and highlight the need to redefine some of its species and reassess their conservation status. We suggest that the conservation status of six species within the group need to be re-evaluated because they exhibit smaller distributions than previously thought; these species are: P. festae, P. gladiator, P. hectus, P. leoni, P. ocreatus, and P. pyrrhomerus. Finally, given that the Pristimantis myersi group, as defined in this work, is monophyletic and morphologically diagnosable, and that Trachyphrynus is an available name for the clade containing P. myersi, we implement Trachyphrynus as a formal subgenus name for the Pristimantis myersi group.

Evaluating a species phylogeny using ddRAD SNPs: Cyto-nuclear discordance and introgression in the salmonid genus Thymallus (Salmonidae)

Hybridization and introgression are very common among freshwater fishes due to the dynamic nature of hydrological landscapes. Cyclic patterns of allopatry and secondary contact provide numerous opportunities for interspecific gene flow, which can lead to discordant paths of evolution for mitochondrial and nuclear genomes. Here, we used double digest restriction-site associated DNA sequencing (ddRADseq) to obtain a genome-wide single nucleotide polymorphism (SNP) dataset comprehensive for allThymallus (Salmonidae)species to infer phylogenetic relationships and evaluate potential recent and historical gene flow among species. The newly obtained nuclear phylogeny was largely concordant with a previously published mitogenome-based topology but revealed a few cyto-nuclear discordances. These incongruencies primarily involved the placement of internal nodes rather than the resolution of species, except for one European species where anthropogenic stock transfers are thought to be responsible for the observed pattern. The analysis of four contact zones where multiple species are found revealed a few cases of mitochondrial capture and limited signals of nuclear introgression. Interestingly, the mechanisms restricting interspecific gene flow might be distinct; while in zones of secondary contact, small-scale physical habitat separation appeared as a limiting factor, biologically based reinforcement mechanisms are presumed to be operative in areas where species presumably evolved in sympatry. Signals of historical introgression were largely congruent with the routes of species dispersal previously inferred from mitogenome data. Overall, the ddRADseq dataset provided a robust phylogenetic reconstruction of the genus Thymallus including new insights into historical hybridization and introgression, opening up new questions concerning their evolutionary history.

A comprehensive molecular phylogeny of the brachyuran crab superfamily Xanthoidea provides novel insights into its systematics and evolutionary history

Maximum likelihood and Bayesian phylogenies for the brachyuran crab superfamily Xanthoidea were estimated based on three mitochondrial and four nuclear genes to infer phylogenetic relationships and inform taxonomy. Habitat data was then used in conjunction with several diversification rates analyses (BAMM, BiSSE, HiSSE, and FiSSE) to test evolutionary hypotheses regarding the diversification of xanthoid crabs. The phylogenies presented are the most comprehensive to date in terms of global diversity as they include all four constituent families (Xanthidae, Panopeidae, Pseudorhombilidae, and Linnaeoxanthidae) spanning all oceans in which xanthoid crabs occur. Six Xanthoidea families are recognised. Panopeidae and Xanthidae sensu stricto are the two largest family-level clades, which are reciprocally monophyletic. Pseudorhombilidae is nested within and is here treated as a subfamily of Panopeidae. Former subfamilies or tribes of Xanthidae sensu lato are basally positioned clades in Xanthoidea and are here assigned family-level ranks: Garthiellidae, Linnaeoxanthidae, Antrocarcinidae, and Nanocassiopidae. The genera Linnaeoxantho and Melybia were recovered in separate clades with Linnaeoxantho being sister to the family Antrocarcinidae, while Melybia was recovered within the family Panopeidae. The existing subfamily classification of Xanthidae and Panopeidae is drastically restructured with 20 xanthid and four panopeid subfamilies provisionally recognised. Diversification-time analyses inferred the origin of Xanthoidea and Garthiellidae in the Eocene, while the other families originated during the Oligocene. The majority of genus- and species-level diversification took place during the Miocene. Ancestral state reconstruction based on depth of occurrence (shallow vs. deep water) shows some ambiguity for the most recent common ancestor of Xanthoidea and Nanocassiopidae. The most recent common ancestors of Antrocarcinidae and Panopeidae were likely deep-water species, while those of Garthiellidae and Xanthidae were probably shallow-water species. Several shifts in net diversification rates were detected but they were not associated with depth-related habitat transitions.

Structure and molecular evolution of the barcode fragment of cytochrome oxidase I (COI) in Macrocheles (Acari: Mesostigmata: Macrochelidae)

Consisting of approximately 320 species, Macrocheles is the most widely distributed genus in the family Macrochelidae. Though some studies have focused on the description of Macrochelidae using molecular techniques (e.g., RAPD) and sequencing of some genes, the interspecies relationships within Macrocheles still remain uncertain. As such, in the present study, we examine all publicly available data in GenBank to explore the evolutionary relationships, divergence times, and amino acid variations within Macrocheles. Exploring the patterns of variation in the secondary protein structure shows high levels of conservation in the second and last helices, emphasizing their involvement in the energy metabolism function of the cytochrome oxidase subunit I enzyme. According to our phylogenetic analysis, all available Macrocheles species are clustered in a monophyletic group. However, in the reconstructed trees, we subdivided M. merdarius and M. willowae into two well-supported intraspecific clades that are driven by geographic separation and host specificity. We also estimate the divergence time of selected species using calibration evidence from available fossils and previous studies. Thus, we estimate that the age of the Parasitiformes is 320.4 (273.3-384.3) Mya (Permian), and the Mesostigmata is 285.1 (270.8-286.4) Mya (Carboniferous), both with likely origins in the Paleozoic era. We also estimate that Macrocheles diverged from other Mesostigmata mites during the Mesozoic, approximately 222.9 Mya.

HIV proviral genetic diversity, compartmentalization and inferred dynamics in lung and blood during long-term suppressive antiretroviral therapy

The lung is an understudied site of HIV persistence. We isolated 898 subgenomic proviral sequences (nef) by single-genome approaches from blood and lung from nine individuals on long-term suppressive antiretroviral therapy (ART), and characterized genetic diversity and compartmentalization using formal tests. Consistent with clonal expansion as a driver of HIV persistence, identical sequences comprised between 8% to 86% of within-host datasets, though their location (blood vs. lung) followed no consistent pattern. The majority (77%) of participants harboured at least one sequence shared across blood and lung, supporting the migration of clonally-expanded cells between sites. The extent of blood proviral diversity on ART was also a strong indicator of diversity in lung (Spearman's ρ = 0.98, p<0.0001). For three participants, insufficient lung sequences were recovered to reliably investigate genetic compartmentalization. Of the remainder, only two participants showed statistically significant support for compartmentalization when analysis was restricted to distinct proviruses per site, and the extent of compartmentalization was modest in both cases. When all within-host sequences (including duplicates) were considered, the number of compartmentalized datasets increased to four. Thus, while a subset of individuals harbour somewhat distinctive proviral populations in blood and lung, this can simply be due to unequal distributions of clonally-expanded sequences. For two participants, on-ART proviruses were also phylogenetically analyzed in context of plasma HIV RNA populations sampled up to 18 years prior, including pre-ART and during previous treatment interruptions. In both participants, on-ART proviruses represented the most ancestral sequences sampled within-host, confirming that HIV sequences can persist in the body for decades. This analysis also revealed evidence of re-seeding of the reservoir during treatment interruptions. Results highlight the genetic complexity of proviruses persisting in lung and blood during ART, and the uniqueness of each individual's proviral composition. Personalized HIV remission and cure strategies may be needed to overcome these challenges.

Genomic analyses of fairy and fulmar prions (Procellariidae: Pachyptila spp.) reveals parallel evolution of bill morphology, and multiple species

Prions are small petrels that are abundant around the Southern Ocean. Here we use mitochondrial DNA (COI and cytochrome b) and nuclear reduced representation sequencing (ddRADseq) to examine the relationships within and between fairy (Pachyptila turtur) and fulmar (P. crassirostris) prions from across their distributions. We found that neither species was recovered as monophyletic, and that at least three species were represented. Furthermore, we detected several genetic lineages that are also morphologically distinct occurring in near sympatry at two locations (Snares Islands and Chatham Islands). The factors that have driven diversification in the fairy/fulmar prion complex are unclear but may include philopatry, differences in foraging distribution during breeding, differences in non-breeding distributions and breeding habitat characteristics. The observed distribution of genetic variation in the fairy/fulmar prion complex is consistent with population expansion from ice-free Last Glacial Maximum refugia into previously glaciated areas.

Comparative mitogenomic analyses provide evolutionary insights into the retrolateral tibial apophysis clade (Araneae: Entelegynae)

The retrolateral tibial apophysis (RTA) clade is the largest spider lineage within Araneae. To better understand the diversity and evolution, we newly determined mitogenomes of ten RTA species from six families and performed a comparative mitogenomics analysis by combining them with 40 sequenced RTA mitogenomes available on GenBank. The ten mitogenomes encoded 37 typical mitochondrial genes and included a large non-coding region (putative control region). Nucleotide composition and codon usage were well conserved within the RTA clade, whereas diversity in sequence length and structural features was observed in control region. A reversal of strand asymmetry in nucleotide composition, i.e., negative AT-skews and positive GC-skews, was observed in each RTA species, likely resulting from mitochondrial gene rearrangements. All protein-coding genes were evolving under purifying selection, except for atp8 whose Ka/Ks was larger than 1, possibly due to positive selection or selection relaxation. Both mutation pressure and natural selection might contribute to codon usage bias of 13 protein-coding genes in the RTA lineage. Phylogenetic analyses based on mitogenomic data recovered a family-level phylogeny within the RTA; {[(Oval calamistrum clade, Dionycha), Marronoid clade], Sparassidae}. This study characterized RTA mitogenomes and provided some new insights into the phylogeny and evolution of the RTA clade.

Lateral transfers lead to the birth of momilactone biosynthetic gene clusters in grass

Momilactone A, an important plant labdane-related diterpenoid, functions as a phytoalexin against pathogens and an allelochemical against neighboring plants. The genes involved in the biosynthesis of momilactone A are found in clusters, i.e., momilactone A biosynthetic gene clusters (MABGCs), in the rice and barnyardgrass genomes. In addition, we know little about the origin and evolution of MABGCs. Here, we integrated results from comprehensive phylogeny and comparative genomic analyses of the core genes of MABGC-like clusters and MABGCs in 40 monocot plant genomes, providing convincing evidence for the birth and evolution of MABGCs in grass species. The MABGCs found in the PACMAD clade of the core grass lineage (including Panicoideae and Chloridoideae) originated from a MABGC-like cluster in Triticeae (BOP clade) via lateral gene transfer (LGT) and followed by recruitment of MAS1/2 and CYP76L1 genes. The MABGCs in Oryzoideae originated from PACMAD through another LGT event and lost CYP76L1 afterwards. The Oryza MABGC and another Oryza diterpenoid cluster c2BGC are two distinct clusters, with the latter originating from gene duplication and relocation within Oryzoideae. Further comparison of the expression patterns of the MABGC genes between rice and barnyardgrass in response to pathogen infection and allelopathy provides novel insights into the functional innovation of MABGCs in plants. Our results demonstrate LGT-mediated origination of MABGCs in grass and shed lights into the evolutionary innovation and optimization of plant biosynthetic pathways.

Comprehensive taxon sampling and vetted fossils help clarify the time tree of shorebirds (Aves, Charadriiformes)

Shorebirds (Charadriiformes) are a globally distributed clade of modern birds and, due to their ecological and morphological disparity, a frequent subject of comparative studies. While molecular phylogenies have been key to establishing the suprafamilial backbone of the charadriiform tree, a number of relationships at both deep and shallow taxonomic levels remain poorly resolved. The timescale of shorebird evolution also remains uncertain as a result of extensive disagreements among the published divergence dating studies, stemming largely from different choices of fossil calibrations. Here, we present the most comprehensive non-supertree phylogeny of shorebirds to date, based on a total-evidence dataset comprising 353 ingroup taxa (90% of all extant or recently extinct species), 27 loci (15 mitochondrial and 12 nuclear), and 69 morphological characters. We further clarify the timeline of charadriiform evolution by time-scaling this phylogeny using a set of 14 up-to-date and thoroughly vetted fossil calibrations. In addition, we assemble a taxonomically restricted 100-locus dataset specifically designed to resolve outstanding problems in higher-level charadriiform phylogeny. In terms of tree topology, our results are largely congruent with previous studies but indicate that some of the conflicts among earlier analyses reflect a genuine signal of pervasive gene tree discordance. Monophyly of the plovers (Charadriidae), the position of the ibisbill (Ibidorhyncha), and the relationships among the five subfamilies of the gulls (Laridae) could not be resolved even with greatly increased locus and taxon sampling. Moreover, several localized regions of uncertainty persist in shallower parts of the tree, including the interrelationships of the true auks (Alcinae) and anarhynchine plovers. Our node-dating and macroevolutionary rate analyses find support for a Paleocene origin of crown-group shorebirds, as well as exceptionally rapid recent radiations of Old World oystercatchers (Haematopodidae) and select genera of gulls. Our study underscores the challenges involved in estimating a comprehensively sampled and carefully calibrated time tree for a diverse avian clade, and highlights areas in need of further research.

Assessment of phylogenetic approaches to study the timing of recombination cessation on sex chromosomes

The evolution of sex chromosomes is hypothesized to be punctuated by consecutive recombination cessation events, forming "evolutionary strata" that ceased to recombine at different time points. The demarcation of evolutionary strata is often assessed by estimates of the timing of recombination cessation (t_RC ) along the sex chromosomes, commonly inferred from the level of synonymous divergence or with species phylogenies at gametologous (X-Y or Z-W) sequence data. However, drift and selection affect sequences unpredictably and introduce uncertainty when inferring t_RC . Here, we assess two alternative phylogenetic approaches to estimate t_RC ; (i) the expected likelihood weight (ELW) approach that finds the most likely topology among a set of hypothetical topologies and (ii) the BEAST approach that estimates t_RC with specified calibration priors on a reference species topology. By using Z and W gametologs of an old and a young evolutionary stratum on the neo-sex chromosome of Sylvioidea songbirds, we show that the ELW and BEAST approaches yield similar t_RC estimates, and that both outperform two frequently applied approaches utilizing synonymous substitution rates (dS) and maximum likelihood (ML) trees, respectively. Moreover, we demonstrate that both ELW and BEAST provide more precise t_RC estimates when sequences of multiple species are included in the analyses.

Mitogenomic phylogeny of Typhlocybinae (Hemiptera: Cicadellidae) reveals homoplasy in tribal diagnostic morphological traits

The subfamily Typhlocybinae is a ubiquitous, highly diverse group of mostly tiny, delicate leafhoppers. The tribal classification has long been controversial and phylogenetic methods have only recently begun to test the phylogenetic status and relationships of tribes. To shed light on the evolution of Typhlocybinae, we performed phylogenetic analyses based on 28 newly sequenced and 19 previously sequenced mitochondrial genomes representing all currently recognized tribes. The results support the monophyly of the subfamily and its sister-group relationship to Mileewinae. The tribe Zyginellini is polyphyletic with some included genera derived independently within Typhlocybini. Ancestral character state reconstruction suggests that some morphological characters traditionally considered important for diagnosing tribes (presence/absence of ocelli, development of hind wing submarginal vein) are homoplastic. Divergence time estimates indicate that the subfamily arose during the Middle Cretaceous and that the extant tribes arose during the Late Cretaceous. Phylogenetic results support establishment of a new genus, Subtilissimia Yan & Yang gen. nov., with two new species, Subtilissimia fulva Yan & Yang sp. nov. and Subtilissimia pellicula Yan & Yang sp. nov.; but indicate that two previously recognized species of Farynala distinguished only by the direction of curvature of the processes of the aedeagus are synonyms, that is, Farynala dextra Yan & Yang, 2017 equals Farynala sinistra Yan & Yang, 2017 syn. nov. A key to tribes of Typhlocybinae is provided.

Gene expression phylogenies and ancestral transcriptome reconstruction resolves major transitions in the origins of pregnancy

Structural and physiological changes in the female reproductive system underlie the origins of pregnancy in multiple vertebrate lineages. In mammals, the glandular portion of the lower reproductive tract has transformed into a structure specialized for supporting fetal development. These specializations range from relatively simple maternal nutrient provisioning in egg-laying monotremes to an elaborate suite of traits that support intimate maternal-fetal interactions in Eutherians. Among these traits are the maternal decidua and fetal component of the placenta, but there is considerable uncertainty about how these structures evolved. Previously, we showed that changes in uterine gene expression contributes to several evolutionary innovations during the origins of pregnancy (Mika et al., 2021b). Here, we reconstruct the evolution of entire transcriptomes ('ancestral transcriptome reconstruction') and show that maternal gene expression profiles are correlated with degree of placental invasion. These results indicate that an epitheliochorial-like placenta evolved early in the mammalian stem-lineage and that the ancestor of Eutherians had a hemochorial placenta, and suggest maternal control of placental invasiveness. These data resolve major transitions in the evolution of pregnancy and indicate that ancestral transcriptome reconstruction can be used to study the function of ancestral cell, tissue, and organ systems.

Morphology, molecular phylogeny and systematics of the diatom genus Fallacia (Sellaphoraceae), with descriptions of three new species1

Fallacia is distinguished morpho-anatomically from Navicula sensu lato based on the possession of an H-shaped chloroplast, lateral sterna and a finely porous conopeum, but whether this genus is monophyletic is still in question. Three new Fallacia species are described based on morphology and SSU rRNA and rbcL gene sequences: Fallacia tateyamensis sp. nov., Fallacia bosoensis sp. nov. and Fallacia laevis sp. nov. We performed the first comprehensive molecular and morphological phylogenetic analyses of 31 Fallacia species based on 11 new sequences from six species and 23 morphological characters. We also documented the detailed morphogenesis of Fallacia for the first time. Fallacia is not monophyletic. Both morphological and DNA sequence data supported the separation of Rossia from Fallacia, while the phylogenetic position of Pseudofallacia is uncertain. We recognized four morphogroups in Fallacia by morphological and molecular phylogenetic analyses. Ancestral character reconstruction indicated that diatoms in Sellaphoraceae evolved from the possession of two lateral narrow parallel depressions covered by narrow nonporous conopea, to lyre-shaped canals covered by wide porous conopea. Lanceolate canals and the presence of areolae in canals evolved multiple times independently.

Metagenomic Analysis Using Phylogenetic Placement-A Review of the First Decade

Phylogenetic placement refers to a family of tools and methods to analyze, visualize, and interpret the tsunami of metagenomic sequencing data generated by high-throughput sequencing. Compared to alternative (e. g., similarity-based) methods, it puts metabarcoding sequences into a phylogenetic context using a set of known reference sequences and taking evolutionary history into account. Thereby, one can increase the accuracy of metagenomic surveys and eliminate the requirement for having exact or close matches with existing sequence databases. Phylogenetic placement constitutes a valuable analysis tool per se, but also entails a plethora of downstream tools to interpret its results. A common use case is to analyze species communities obtained from metagenomic sequencing, for example via taxonomic assignment, diversity quantification, sample comparison, and identification of correlations with environmental variables. In this review, we provide an overview over the methods developed during the first 10 years. In particular, the goals of this review are 1) to motivate the usage of phylogenetic placement and illustrate some of its use cases, 2) to outline the full workflow, from raw sequences to publishable figures, including best practices, 3) to introduce the most common tools and methods and their capabilities, 4) to point out common placement pitfalls and misconceptions, 5) to showcase typical placement-based analyses, and how they can help to analyze, visualize, and interpret phylogenetic placement data.

High Diversity of Type I Polyketide Genes in Bacidia rubella as Revealed by the Comparative Analysis of 23 Lichen Genomes

Fungi involved in lichen symbioses produce a large array of secondary metabolites that are often diagnostic in the taxonomic delimitation of lichens. The most common lichen secondary metabolites-polyketides-are synthesized by polyketide synthases, particularly by Type I PKS (TI-PKS). Here, we present a comparative genomic analysis of the TI-PKS gene content of 23 lichen-forming fungal genomes from Ascomycota, including the de novo sequenced genome of Bacidia rubella. Firstly, we identify a putative atranorin cluster in B. rubella. Secondly, we provide an overview of TI-PKS gene diversity in lichen-forming fungi, and the most comprehensive Type I PKS phylogeny of lichen-forming fungi to date, including 624 sequences. We reveal a high number of biosynthetic gene clusters and examine their domain composition in the context of previously characterized genes, confirming that PKS genes outnumber known secondary substances. Moreover, two novel groups of reducing PKSs were identified. Although many PKSs remain without functional assignments, our findings highlight that genes from lichen-forming fungi represent an untapped source of novel polyketide compounds.

Early branching arbuscular mycorrhizal fungus Paraglomus occultum carries a small and repeat-poor genome compared to relatives in the Glomeromycotina

The arbuscular mycorrhizal fungi (AMFs) are obligate root symbionts in the subphylum Glomeromycotina that can benefit land plants by increasing their soil nutrient uptake in exchange for photosynthetically fixed carbon sources. To date, annotated genome data from representatives of the AMF orders Glomerales, Diversisporales and Archaeosporales have shown that these organisms have large and highly repeated genomes, and no genes to produce sugars and fatty acids. This led to the hypothesis that the most recent common ancestor (MRCA) of Glomeromycotina was fully dependent on plants for nutrition. Here, we aimed to further test this hypothesis by obtaining annotated genome data from a member of the early diverging order Paraglomerales (Paraglomus occultum). Genome analyses showed this species carries a 39.6 Mb genome and considerably fewer genes and repeats compared to most AMF relatives with annotated genomes. Consistent with phylogenies based on ribosomal genes, our phylogenetic analyses suggest P. occultum as the earliest diverged branch within Glomeromycotina. Overall, our analyses support the view that the MRCA of Glomeromycotina carried hallmarks of obligate plant biotrophy. The small genome size and content of P. occultum could either reflect adaptive reductive processes affecting some early AMF lineages, or indicate that the high gene and repeat family diversity thought to drive AMF adaptability to host and environmental change was not an ancestral feature of these prominent plant symbionts.

Comparative genomics and evolutionary analysis of Lactococcus garvieae isolated from human endocarditis

Lactococcus garvieae is a well-known pathogen of fish, but is rarely involved in infections in humans and other mammals. In humans, the main clinical manifestation of L. garvieae infections is endocarditis usually related to the ingestion of contaminated food, such as undercooked fish and shellfish. This study presents the first complete genomic sequence of a clinical L. garvieae strain isolated from a patient with endocarditis and its comparative analysis with other genomes. This human isolate contains a circular chromosome of 2 099 060 bp and one plasmid of 50 557 bp. In comparison with other fully sequenced L. garvieae strains, the chromosomal DNA of L. garvieae Lg-Granada carries a low proportion of insertion sequence elements and a higher number of putative prophages. Our results show that, in general, L. garvieae is a highly recombinogenic species with an open pangenome in which almost 30 % of its genome has undergone horizontal transfers. Within the genus Lactococcus, L. lactis is the main donor of genetic components to L. garvieae but, taking Lg-Granada as a representative, this bacterium tends to import more genes from Bacilli taxa than from other Lactococcus species.

Evolutionary processes in the emergence and recent spread of the syphilis agent, Treponema pallidum

The incidence of syphilis has risen worldwide in the last decade in spite of being an easily treated infection. The causative agent of this sexually transmitted disease is the bacterium Treponema pallidum subspecies pallidum (TPA), very closely related to subsp. pertenue (TPE) and endemicum (TEN), responsible for the human treponematoses yaws and bejel, respectively. Although much focus has been placed on the question of the spatial and temporary origins of TPA, the processes driving the evolution and epidemiological spread of TPA since its divergence from TPE and TEN are not well understood. Here, we investigate the effects of recombination and selection as forces of genetic diversity and differentiation acting during the evolution of T. pallidum subspecies. Using a custom-tailored procedure, named phylogenetic incongruence method, with 75 complete genome sequences, we found strong evidence for recombination among the T. pallidum subspecies, involving 12 genes and 21 events. In most cases, only one recombination event per gene was detected and all but one event corresponded to intersubspecies transfers, from TPE/TEN to TPA. We found a clear signal of natural selection acting on the recombinant genes, which is more intense in their recombinant regions. The phylogenetic location of the recombination events detected and the functional role of the genes with signals of positive selection suggest that these evolutionary processes had a key role in the evolution and recent expansion of the syphilis bacteria and significant implications for the selection of vaccine candidates and the design of a broadly protective syphilis vaccine.

Citrullination Was Introduced into Animals by Horizontal Gene Transfer from Cyanobacteria

Protein posttranslational modifications add great sophistication to biological systems. Citrullination, a key regulatory mechanism in human physiology and pathophysiology, is enigmatic from an evolutionary perspective. Although the citrullinating enzymes peptidylarginine deiminases (PADIs) are ubiquitous across vertebrates, they are absent from yeast, worms, and flies. Based on this distribution PADIs were proposed to have been horizontally transferred, but this has been contested. Here, we map the evolutionary trajectory of PADIs into the animal lineage. We present strong phylogenetic support for a clade encompassing animal and cyanobacterial PADIs that excludes fungal and other bacterial homologs. The animal and cyanobacterial PADI proteins share functionally relevant primary and tertiary synapomorphic sequences that are distinct from a second PADI type present in fungi and actinobacteria. Molecular clock calculations and sequence divergence analyses using the fossil record estimate the last common ancestor of the cyanobacterial and animal PADIs to be less than 1 billion years old. Additionally, under an assumption of vertical descent, PADI sequence change during this evolutionary time frame is anachronistically low, even when compared with products of likely endosymbiont gene transfer, mitochondrial proteins, and some of the most highly conserved sequences in life. The consilience of evidence indicates that PADIs were introduced from cyanobacteria into animals by horizontal gene transfer (HGT). The ancestral cyanobacterial PADI is enzymatically active and can citrullinate eukaryotic proteins, suggesting that the PADI HGT event introduced a new catalytic capability into the regulatory repertoire of animals. This study reveals the unusual evolution of a pleiotropic protein modification.

Phylogenomics resolves ambiguous relationships within Aciculata (Errantia, Annelida)

Aciculata (Eunicida + Phyllodocida) is among the largest clades of annelids, comprising almost half of the known diversity of all marine annelids. Despite the group's large size and biological importance, most phylogenomic studies on Annelida to date have had a limited sampling of this clade. The phylogenetic placement of many clades within Phyllodocida in particular has remained poorly understood. To resolve the relationships within Aciculata we conducted a large-scale phylogenomic analysis based on 24 transcriptomes (13 new), chosen to represent many family-ranked taxa that have never been included in a broad phylogenomic study. Our sampling also includes several enigmatic taxa with challenging phylogenetic placement, such as Histriobdella, Struwela, Lacydonia, Pilargis and the holopelagic worms Lopadorrhynchus, Travisiopsis and Tomopteris. Our robust phylogeny allows us to name and place some of these problematic clades and has significant implications on the systematics of the group. Within Eunicida we reinstate the names Eunicoidea and Oenonoidea. Within Phyllodocida we delineate Phyllodociformia, Glyceriformia, Nereidiformia, Nephtyiformia and Aphroditiformia. Phyllodociformia now includes: Lacydonia, Typhloscolecidae, Lopadorrhynchidae and Phyllodocidae. Nephtyiformia includes Nephtyidae and Pilargidae. We also broaden the delineation of Glyceriformia to include Sphaerodoridae, Tomopteridae and Glyceroidea (Glyceridae + Goniadidae). Furthermore, our study demonstrates and explores how conflicting, yet highly supported topologies can result from confounding signals in gene trees.