Plastome evolution in Santalales involves relaxed selection prior to loss of ndh genes and major boundary shifts of the inverted repeat.

BACKGROUND AND AIMS: Biological aspects of haustorial parasitism have significant effects on the configuration of the plastid genome. Approximately half the diversity of haustorial parasites belongs to the order Santalales, where a clearer picture of plastome evolution in relation to parasitism is starting to emerge. However, in previous studies of plastome evolution there is still a notable under-representation of members from non-parasitic and deep-branching hemiparasitic lineages, limiting evolutionary inference around the time of transition to a parasitic lifestyle. To expand taxon sampling relevant to this transition we therefore targeted three families of non-parasites (Erythropalaceae, Strombosiaceae, and Coulaceae), two families of root-feeding hemiparasites (Ximeniaceae and Olacaceae), and two families of uncertain parasitic status (Aptandraceae and Octoknemaceae). With data from these lineages we aimed to explore plastome evolution in relation to evolution of parasitism. METHODS: From 29 new samples we sequenced and annotated plastomes and the nuclear ribosomal cistron. We examined phylogenetic patterns, plastome evolution, and patterns of relaxed or intensified selection in plastid genes. Available transcriptome data were analyzed to investigate potential transfer of infA to the nuclear genome. RESULTS: Phylogenetic relationships indicate a single functional loss of all plastid ndh genes (ndhA-K) in a clade formed by confirmed parasites and Aptandraceae, and the loss coincides with major size and boundary shifts of the inverted repeat (IR) region. Depending on an autotrophic or heterotrophic lifestyle in Aptandraceae, plastome changes are either correlated with or predate evolution of parasitism. Phylogenetic patterns also indicate repeated loss of infA from the plastome, and based on presence of transcribed sequences with presequences corresponding to thylakoid luminal transit peptides, we infer that the genes were transferred to the nuclear genome. CONCLUSIONS: Except for the loss of the ndh complex, relatively few genes have been lost from the plastome in deep-branching root parasites in Santalales. Prior to loss of the ndh genes, they show signs of relaxed selection indicative of their dispensability. To firmly establish a potential correlation between ndh gene loss, plastome instability and evolution of parasitism, it is pertinent to refute or confirm a parasitic lifestyle all Santalales clades.

TopHap: rapid inference of key phylogenetic structures from common haplotypes in large genome collections with limited diversity.

MOTIVATION: Building reliable phylogenies from very large collections of sequences with a limited number of phylogenetically informative sites is challenging because sequencing errors and recurrent/backward mutations interfere with the phylogenetic signal, confounding true evolutionary relationships. Massive global efforts of sequencing genomes and reconstructing the phylogeny of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strains exemplify these difficulties since there are only hundreds of phylogenetically informative sites but millions of genomes. For such datasets, we set out to develop a method for building the phylogenetic tree of genomic haplotypes consisting of positions harboring common variants to improve the signal-to-noise ratio for more accurate and fast phylogenetic inference of resolvable phylogenetic features. RESULTS: We present the TopHap approach that determines spatiotemporally common haplotypes of common variants and builds their phylogeny at a fraction of the computational time of traditional methods. We develop a bootstrap strategy that resamples genomes spatiotemporally to assess topological robustness. The application of TopHap to build a phylogeny of 68 057 SARS-CoV-2 genomes (68KG) from the first year of the pandemic produced an evolutionary tree of major SARS-CoV-2 haplotypes. This phylogeny is concordant with the mutation tree inferred using the co-occurrence pattern of mutations and recovers key phylogenetic relationships from more traditional analyses. We also evaluated alternative roots of the SARS-CoV-2 phylogeny and found that the earliest sampled genomes in 2019 likely evolved by four mutations of the most recent common ancestor of all SARS-CoV-2 genomes. An application of TopHap to more than 1 million SARS-CoV-2 genomes reconstructed the most comprehensive evolutionary relationships of major variants, which confirmed the 68KG phylogeny and provided evolutionary origins of major and recent variants of concern. AVAILABILITY AND IMPLEMENTATION: TopHap is available at https://github.com/SayakaMiura/TopHap. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

An Evolutionary Portrait of the Progenitor SARS-CoV-2 and Its Dominant Offshoots in COVID-19 Pandemic.

Global sequencing of genomes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has continued to reveal new genetic variants that are the key to unraveling its early evolutionary history and tracking its global spread over time. Here we present the heretofore cryptic mutational history and spatiotemporal dynamics of SARS-CoV-2 from an analysis of thousands of high-quality genomes. We report the likely most recent common ancestor of SARS-CoV-2, reconstructed through a novel application and advancement of computational methods initially developed to infer the mutational history of tumor cells in a patient. This progenitor genome differs from genomes of the first coronaviruses sampled in China by three variants, implying that none of the earliest patients represent the index case or gave rise to all the human infections. However, multiple coronavirus infections in China and the United States harbored the progenitor genetic fingerprint in January 2020 and later, suggesting that the progenitor was spreading worldwide months before and after the first reported cases of COVID-19 in China. Mutations of the progenitor and its offshoots have produced many dominant coronavirus strains that have spread episodically over time. Fingerprinting based on common mutations reveals that the same coronavirus lineage has dominated North America for most of the pandemic in 2020. There have been multiple replacements of predominant coronavirus strains in Europe and Asia as well as continued presence of multiple high-frequency strains in Asia and North America. We have developed a continually updating dashboard of global evolution and spatiotemporal trends of SARS-CoV-2 spread (http://sars2evo.datamonkey.org/).

Agathis trees of Patagonia's Cretaceous-Paleogene death landscapes and their evolutionary significance.

PREMISE OF THE STUDY: The fossil record of Agathis historically has been restricted to Australasia. Recently described fossils from the Eocene of Patagonian Argentina showed a broader distribution than found previously, which is reinforced here with a new early Paleocene Agathis species from Patagonia. No previous phylogenetic analyses have included fossil Agathis species. METHODS: We describe macrofossils from Patagonia of Agathis vegetative and reproductive organs from the early Danian, as well as leaves with Agathis affinities from the latest Maastrichtian. A total evidence phylogenetic analysis is performed, including the new Danian species together with other fossil species having agathioid affinities. KEY RESULTS: Early Danian Agathis immortalis sp. nov. is the oldest definite occurrence of Agathis and one of the most complete Agathis species in the fossil record. Leafy twigs, leaves, pollen cones, pollen, ovuliferous complexes, and seeds show features that are extremely similar to the living genus. Dilwynites pollen grains, associated today with both Wollemia and Agathis and known since the Turonian, were found in situ within the pollen cones. CONCLUSIONS: Agathis was present in Patagonia ca. 2 million years after the K-Pg boundary, and the putative latest Cretaceous fossils suggest that the genus survived the K-Pg extinction. Agathis immortalis sp nov. is recovered in a stem position for the genus, while A. zamunerae (Eocene, Patagonia) is recovered as part of the crown. A Mesozoic divergence for the Araucariaceae crown group, previously challenged by molecular divergence estimates, is supported by the combined phylogenetic analyses including the fossil taxa.

Genetic Structure of the Bacterial Endosymbiont Buchnera aphidicola from Its Host Aphid Schlechtendalia chinensis and Evolutionary Implications.

Buchnera aphidicola is a primary symbiotic bacterium which provides essential amino acids to aphids. In this study, we sequenced nuclear 16s rDNA and atpAGD genes for 156 individuals of B. aphidicola from eight geographically distant populations to investigate the genetic diversity and structure of B. aphidicola associated to the sumac gall aphid Schlechtendalia chinensis in central and southern China. Our analyses of the combined sequences showed that B. aphidicola from S. chinensis had high haplotype and nucleotide diversity (h = 0.893; π = 0.00164). One of the 16 haplotypes detected had a wide geographic distribution across the central and southern China and was probably the ancestral haplotype of B. aphidicola from S. chinensis. A network and phylogenetic analysis revealed a geographic structure in which the 16 haplotypes of B. aphidicola were divided into the northern and southern clades separated by the Yangtze River. The two clades diverged from each other at 22.1 ± 3.7 Mya according to our divergence time estimations. Therefore, the modern genetic structure in B. aphidicola from S. chinensis has been probably impacted by historical geological events. Combined with the data from GenBank, we also reconstructed the phylogenetic relationships of three aphid subfamilies and their symbiont bacteria. The results indicated significant topological correlations between the aphid and bacterial phylogenies at interspecific levels.

Comparative analyses of eight complete plastid genomes of two hemiparasitic Cassytha vines in the family Lauraceae.

Cassytha is the sole genus of hemiparasitic vines (ca. 20 spp.) belonging to the Cassytheae tribe of the Lauraceae family. It is extensively distributed in tropical and subtropical regions. In this study, we determined the complete plastid genome sequences of C. filiformis and C. larsenii, which do not possess the typical quadripartite structure. The length of C. filiformis plastomes ranged from 114,215 to 114,618 bp, whereas that of C. larsenii plastomes ranged from 114,900 to 114,988 bp. Comparative genomic analysis revealed 1,013 mutation sites, four large intragenomic deletions, and five highly variable regions in the eight plastome sequences. Phylogenetic analyses based on 61 complete plastomes of Laurales species, 19 ITS sequences, and trnK barcodes from 91 individuals of Cassytha spp. confirmed a non-basal group comprising individuals of C. filiformis, C. larsenii, and C. pubescens in the family Lauraceae and proposed a sister relationship between C. filiformis and C. larsenii. Further morphological comparisons indicated that the presence or absence of hairs on the haustoria and the shape or size of fruits were useful traits for differentiating C. filiformis and C. larsenii.

The complete chloroplast genome and phylogenetic relationship of Apocynum pictum (Apocynaceae), a Central Asian shrub and second-class national protected species of western China.

Apocynum pictum of the dogbane family, Apocynaceae, is a perennial semi-shrub species of ecological, medicinal, and economic value. It is mainly distributed in semi-arid, saline-alkaline, and desert regions of Xinjiang, Qinghai, and Gansu of western China and adjacent regions from Kazakhstan and Mongolia. Here, we reported the complete chloroplast (cp) genome of A. pictum for the first time, and we found that it had a circular structure with an estimated length of 150,749 bp and a GC content of 38.3%. The cp genome was composed of a large single copy (LSC), a single small single copy (SSC), and two inverted repeat (IR) regions, which were 81,888 bp, 17,251 bp and 25,805 bp long, respectively. The cp genome of A. pictum encoded 134 genes and contained 66 simple sequence repeats (SSRs). A comparative analysis with other cp genomes from Apocynaceae indicated that the cp genome of A. pictum was very conserved, except for subtle differences occurring in the protein-coding genes accD, ndhF, rpl22, rpl32, rpoC2, ycf1 and ycf2. A phylogenetic reconstruction showed that A. pictum and A. venetum were sister species, forming a strongly supported clade with Trachelospermum. Interestingly, nucleotide substitution ratios (Ka/Ks) between A. pictum and A. venetum on accD and ndhF were >1.0, suggesting positive selective pressure on these genes. Our result enriches the genomic resources for the diverse dogbane family and provides critical molecular resources to develop future studies on ecological adaptation to desert habitats in Apocynum.

Decaisninatomentosa (Loranthaceae), a new species of mistletoe from Samar Island, Philippines.

Background: The extensive forests over limestone of the Samar Island Natural Park (SINP) on Samar Island, Philippines harbour a rich variety of unique species. In this contribution, we describe and illustrate a new Loranthaceous mistletoe, endemic to Samar Island named Decaisninatomentosa, representing the 12th member of the genus reported to the Philippines. New information: This new species is similar to D.confertiflora (Merr.) Barlow with respect to the presence of shortly and densely off-white tomentose inflorescence and 6-merous flowers. However, it is unique amongst congeners in having tomentose and partially fused bracteoles which cover almost or entirely the ovary of individual flowers in the triads. To date, D.tomentosa seems to be restricted to the SINP and is only known from a handful of individuals. More studies are needed to properly assess the demography, host range, conservation status and phylogenetic position of this distinctive species of mistletoe.

TopHap: Rapid inference of key phylogenetic structures from common haplotypes in large genome collections with limited diversity.

MOTIVATION: Building reliable phylogenies from very large collections of sequences with a limited number of phylogenetically informative sites is challenging because sequencing errors and recurrent/backward mutations interfere with the phylogenetic signal, confounding true evolutionary relationships. Massive global efforts of sequencing genomes and reconstructing the phylogeny of SARS-CoV-2 strains exemplify these difficulties since there are only hundreds of phylogenetically informative sites and millions of genomes. For such datasets, we set out to develop a method for building the phylogenetic tree of genomic haplotypes consisting of positions harboring common variants to improve the signal-to-noise ratio for more accurate phylogenetic inference of resolvable phylogenetic features. RESULTS: We present the TopHap approach that determines spatiotemporally common haplotypes of common variants and builds their phylogeny at a fraction of the computational time of traditional methods. To assess topological robustness, we develop a bootstrap resampling strategy that resamples genomes spatiotemporally. The application of TopHap to build a phylogeny of 68,057 genomes (68KG) produced an evolutionary tree of major SARS-CoV-2 haplotypes. This phylogeny is concordant with the mutation tree inferred using the co-occurrence pattern of mutations and recovers key phylogenetic relationships from more traditional analyses. We also evaluated alternative roots of the SARS-CoV-2 phylogeny and found that the earliest sampled genomes in 2019 likely evolved by four mutations of the most recent common ancestor of all SARS-CoV-2 genomes. An application of TopHap to more than 1 million genomes reconstructed the most comprehensive evolutionary relationships of major variants, which confirmed the 68KG phylogeny and provided evolutionary origins of major variants of concern. AVAILABILITY: TopHap is available on the web at https://github.com/SayakaMiura/TopHap . CONTACT: s.kumar@temple.edu.

An evolutionary portrait of the progenitor SARS-CoV-2 and its dominant offshoots in COVID-19 pandemic.

We report the likely most recent common ancestor of SARS-CoV-2 - the coronavirus that causes COVID-19. This progenitor SARS-CoV-2 genome was recovered through a novel application and advancement of computational methods initially developed to reconstruct the mutational history of tumor cells in a patient. The progenitor differs from the earliest coronaviruses sampled in China by three variants, implying that none of the earliest patients represent the index case or gave rise to all the human infections. However, multiple coronavirus infections in China and the USA harbored the progenitor genetic fingerprint in January 2020 and later, suggesting that the progenitor was spreading worldwide as soon as weeks after the first reported cases of COVID-19. Mutations of the progenitor and its offshoots have produced many dominant coronavirus strains, which have spread episodically over time. Fingerprinting based on common mutations reveals that the same coronavirus lineage has dominated North America for most of the pandemic. There have been multiple replacements of predominant coronavirus strains in Europe and Asia and the continued presence of multiple high-frequency strains in Asia and North America. We provide a continually updating dashboard of global evolution and spatiotemporal trends of SARS-CoV-2 spread (http://sars2evo.datamonkey.org/).

Splitting the Pisonia birdcatcher trees: re-establishment of Ceodes and Rockia (Nyctaginaceae, Pisonieae).

Several genera of Nyctaginaceae, currently merged under Pisonia, have been described for the Indo-Pacific region. Results from a recent molecular phylogenetic study of tribe Pisonieae showed that Pisonia is non-monophyletic and comprises three well-supported lineages: one including typical Pisonia and allies (Pisonia s.str.), a clade of species which corresponds to the original description of Ceodes and a third lineage whose single representative was formerly treated under the monotypic genus Rockia. Thus, as part of an effort to achieve a natural classification for tribe Pisonieae, this work proposes to re-establish Ceodes and Rockia to accommodate taxa with inconspicuous glands on anthocarps, recognising 21 species (20 for the former and one for the latter), of which 16 are new combinations: Ceodes amplifolia comb. nov., Ceodes artensis comb. nov., Ceodes austro-orientalis comb. nov., Ceodes brownii comb. nov., Ceodes cauliflora comb. nov., Ceodes coronata comb. nov., Ceodes diandra comb. nov., Ceodes gigantocarpa comb. nov., Ceodes gracilescens comb. nov., Ceodes lanceolata comb. nov., Ceodes merytifolia comb. nov., Ceodes muelleriana comb. nov., Ceodes rapaensis comb. nov., Ceodes sechellarum comb. nov., Ceodes taitensis comb. nov. and Ceodes wagneriana comb. nov. A general distribution of each species recognised in this work is also included, along with line drawings and colour pictures of representative species of Ceodes, Pisonia and Rockia and an updated dichotomous key based on reproductive characters for the nine genera (Ceodes, Cephalotomandra, Grajalesia, Guapira, Neea, Neeopsis, Pisonia, Pisoniella and Rockia) comprising the tribe Pisonieae. Résumé Plusieurs genres de Nyctaginaceae actuellement fusionnés sous Pisonia ont été décrits pour la région Indo-Pacifique. Les résultats d'une récente étude phylogénétique moléculaire de la tribu Pisonieae ont montré que Pisonia est non monophylétique et comprend trois lignées bien supportées: une comprenant Pisonia typique et ses alliés (Pisonia s.str.), un clade d'espèces qui correspond à la description originale de Ceodes et une troisième lignée dont l'unique représentant était auparavant traité sous le genre monotypique Rockia. Ainsi, dans le cadre d'un effort pour parvenir à une classification naturelle de la tribu Pisonieae, ce travail proposons de rétablir les Ceodes et Rockia pour accueillir des taxons avec des glandes discrètes sur les anthocarpes, reconnaissant 21 espèces (20 pour les premières et une pour les dernières), dont 16 sont de nouvelles combinaisons: Ceodes amplifolia comb. nov., Ceodes artensis comb. nov., Ceodes austro-orientalis comb. nov., Ceodes brownii comb. nov., Ceodes cauliflora comb. nov., Ceodes coronata comb. nov., Ceodes diandra comb. nov., Ceodes gigantocarpa comb. nov., Ceodes gracilescens comb. nov., Ceodes lanceolata comb. nov., Ceodes merytifolia comb. nov., Ceodes muelleriana comb. nov., Ceodes rapaensis comb. nov., Ceodes sechellarum comb. nov., Ceodes taitensis comb. nov. et Ceodes wagneriana comb. nov. Une distribution générale de chaque espèce reconnue dans ce travail est également incluse, ainsi que des dessins au trait et des images en couleur des espèces représentatives de Ceodes, Pisonia et Rockia, et préparé une clé dichotomique mise à jour basée sur les caractères reproductifs des neuf genres (Ceodes, Cephalotomandra, Grajalesia, Guapira, Neea, Neeopsis, Pisonia, Pisoniella et Rockia) comprenant la tribu Pisonieae.

Two new species of Dendrophthora (Viscaceae) from the Venezuelan Andes.

Two new species of Dendrophthora Eichler (Viscaceae) from northwestern Venezuela are described and illustrated. Both mistletoes, D. apiculata Canelón et al., sp. nov. and D. coronata Canelón et al., sp. nov., are confined to subpáramo and páramo ecosystems of the Venezuelan Andes and are, at present, only known from Guaramacal National Park (Portuguesa and Trujillo states). Ecological aspects and possible taxonomic affinities are discussed. A distribution map also is presented.

ResumenSe describen e ilustran dos nuevas especies de Dendrophthora Eichler (Viscaceae) del noroeste de Venezuela. Ambos muérdagos, D. apiculata Canelón et al., sp. nov. y D. coronata Canelón et al., sp. nov., se limitan a los ecosistemas subpáramo y páramo de los Andes venezolanos y, en la actualidad, solo se conocen en el Parque Nacional Guaramacal (estados Portuguesa y Trujillo). Se discuten aspectos ecológicos y posibles afinidades taxonómicas. También se presenta un mapa de distribución.

A distinctive new species of flowerpecker (Passeriformes: Dicaeidae) from Borneo.

The enigmatic 'Spectacled Flowerpecker'-a probable new bird species from the island of Borneo-was first sighted in the Danum Valley of Sabah, Malaysia in 2009. However, the absence of a holotype specimen has prevented its formal scientific description. Since then only a handful of reports from widely disparate localities across the island have emerged, all from lowland sites and often in close association with fruiting mistletoe. Here, we report the long-awaited capture of a specimen of this putative new species and confirm its morphological and molecular distinctiveness as a novel species in the genus Dicaeum.

Two new endemic tree species from Puerto Rico: Pisonia horneae and Pisonia roqueae (Nyctaginaceae).

In this paper, we describe two endemic tree species of Pisonia (Caryophyllales: Nyctaginaceae) from Puerto Rico that were erroneously catalogued under the single name Pisonia subcordata var. typica f. gigantophylla, misidentified as P. albida or P. subcordata, and informally named as "P. borinquena" and "P. woodburyana". The species here named as P. horneae is a rare to locally occasional tree from low elevations in the Northern Karst and the Sierra de Cayey. The other species, here named as P. roqueae, is a rare to locally common tree from mid to high elevations in the Central Mountain Range and the Luquillo Mountains. We provide an account of the taxonomical and nomenclatural history of both species, images, conservation notes, a distribution map, and a key to distinguish the species of Pisonia present in Puerto Rico.

ResumenEn esta publicación se describen dos especies de árboles endémicos de Pisonia (Caryophyllales: Nyctaginaceae) de Puerto Rico, las cuales fueron erróneamente catalogadas bajo un solo nombre como Pisonia subcordata var. typica f. gigantophylla, mal identificadas como P. albida o P. subcordata, e informalmente nombradas como "P. borinquena" y "P. woodburyana". La especie aquí nombrada como P. horneae es un árbol raro a localmente ocasional de bajas elevaciones en el Karso Norteño y la Sierra de Cayey. La segunda especie aquí nombrada como P. roqueae es un árbol raro o localmente común de elevaciones medias a altas en la Cordillera Central y las Montañas de Luquillo. Se provee un recuento de la historia taxonómica y nomenclatural de ambas especies, imágenes, notas de conservación, un mapa de distribución, y una clave para distinguir las especies de Pisonia presentes en Puerto Rico.