Hybrid Origin Research Articles

Evaluating hybrid speciation and swamping in wild carnivores with a decision-tree approach.

Hybridization is an important evolutionary force with a principal role in the origin of new species, known as hybrid speciation. However, ongoing hybridization can create hybrid swamping, in which parental genomes are completely lost. This can become a biodiversity threat if it involves species that have adapted to certain environmental conditions and occur nowhere else. Because conservation scientists commonly have a negative attitude toward hybrids, it is important to improve understanding of the influence of interspecific gene flow on the persistence of species. We reviewed the literature on species hybridization to build a list of all known cases in the order Carnivora. To examine the relative impact, we also noted level of introgression, whether fertile offspring were produced, and whether there was mention of negative or positive evolutionary effects (hybrid speciation and swamping). To evaluate the conservation implications of hybrids, we developed a decision-making tree with which to determine which actions should be taken to manage hybrid species. We found 53 hybrids involving 68 unique taxa, which is roughly 23% of all carnivore species. They mainly involved monophyletic (83%) and sympatric species (75%). For 2 species, the outcome of the assessment was to eliminate or restrict the hybrids: Ethiopian wolf (Canis simensis) and Scottish wildcat (Felis silvestris silvestris). Both species hybridize with their domestic conspecifics. For all other cases, we suggest hybrids be protected in the same manner as native species. We found no evidence of genomic extinction in Carnivora. To the contrary, some species appear to be of hybrid origin, such as the Asiatic black bear (Ursus thibetanus) and African golden wolf (Canis lupaster). Other positive outcomes of hybridization are novel genetic diversity, adaptation to extreme environments, and increased reproductive fitness. These outcomes are particularly valuable for counterbalancing genetic drift and enabling adaptive introgression in a human-dominated world.

Two-headed parthenogenetic lizard embryo from southern Georgia

Abstract Visual inspection of several embryos of the parthenogenetic lizard Darevskia armeniaca revealed the presence of an embryo with axial bifurcation (“two-headed”) on the stage of pigmented eyes and plate-like limb buds with a distinct border at the edges. This is the third recorded case of axial bifurcation in D. armeniaca, although two previous cases were mentioned without further discussion. Here the bicephalic embryo is described in detail and the potential reasons are discussed. The analysis of the literature on axial bifurcation in lacertids suggests that this type of developmental disorder may be particularly common in this parthenogenetic form. Hybridization may cause multiple developmental disorders, including incomplete separation of twin embryos; all parthenogenetic Darevskia have a hybrid origin, and this may cause the disorders rather than parthenogenetic reproduction by itself. The hypothesis needs further study with more representative samples of parthenogenetic and sexually reproducing Darevskia.

Phenological phases of <i>Weigela×wagneri</i> L. H. Bailey under conditions of humid subtropics in Russia

Weigela varieties of hybrid origin, known as Weigela hortensis (W. hortensis C.A. Mey) or <i>Weigela×wagneri</i> (W.wagneri L. H. Bailey) are cultivated on the Black Sea coast of Krasnodar Krai. A current range of this beautifully flowering shrub includes more than 150 varieties. However, only 24 grow in the region and are predominately selected in the early XX century and are rarely used in the landscaping of the resort town. Ornamental varieties of Weigela grow mostly in limited use areas (Sochi Arboretum, Subtropical Botanical Garden in Kuban region, Friendship Tree Garden Museum). The study aims at investigating the phenological phases of <i>Weigela×wagneri</i> L. H. Bailey under humid subtropical conditions of the Black Sea coast, Krasnodar Krai, to be used for the design of gardens with continuous flowering plants, as well as for breeding. The study was conducted in the period from 2013 to 2019 in the Friendship Tree Garden Museum and Subtropical Botanical Garden in Kuban region. The study involved 15 varieties of W.×wagneri. The authors established differences in phenological phases, including the start/end of growing season and flowering, duration of these periods, as well as the sums of effective temperatures required for these phases. The start of the growing season was established to vary from February 12 (Arlequin) with an accumulated sum of effective temperature of 261.2℃ to March 14 (Brictol Ruby) and a sum of temperature of 376.9℃. Differences between varieties in this phenophase account for 30 days. On the basis of the long-term average annual data, the varieties were divided into groups according to the floral initiation: early flowering (from April 14 to April 21) group included Arlequin, Gustave Malet, Mon Blanc, Newport Red, Venusta, Madame Lemoine; medium-flowering (April 22 to April 30) group included Lacepede, Ballet, Pavillon Blanc, Brictol Ruby, Madame Lemoine; Eva Ratke, Kosteriana variegata, Red Prince, Augusta were included into a late-flowering (from May 01 to May 06) group. According to the dates of the start and end of growing season, the varieties were divided into the following phenological groups: EE – Early starting (before Feb 12) and Early ending vegetation (before Dec 05); EL – Early starting (before Feb 12) and Late ending (after Dec 19); LE – Late starting (after March 4) and Early ending (before Dec 5); LL – Late starting (after March 4) and Late ending vegetation (after Dec 19).

Sex-determining region complements traditionally used in phylogenetic studies nuclear and chloroplast sequences in investigation of Aigeiros Duby and Tacamahaca Spach poplars (genus Populus L., Salicaceae).

Members of the genus Populus L. play an important role in the formation of forests in the northern hemisphere and are used in urban landscaping and timber production. Populus species of closely related sections show extensive hybridization. Therefore, the systematics of the genus is rather complicated, especially for poplars of hybrid origin. We aimed to assess the efficiency of application of the sex-determining region (SDR) in addition to the nuclear and chloroplast genome loci traditionally used in phylogenetic studies of poplars to investigate relationships in sections Aigeiros Duby and Tacamahaca Spach. Targeted deep sequencing of NTS 5S rDNA, ITS, DSH 2, DSH 5, DSH 8, DSH 12, DSH 29, 6, 15, 16, X18, trnG-psbK-psbI, rps2-rpoC2, rpoC2-rpoC1, as well as SDR and ARR17 gene was performed for 379 poplars. The SDR and ARR17 gene together with traditionally used multicopy and single-copy loci of nuclear and chloroplast DNA allowed us to obtain a clustering that is most consistent with poplar systematics based on morphological data and to shed light on several controversial hypotheses about the origin of the studied taxa (for example, the inexpediency of separating P. koreana, P. maximowiczii, and P. suaveolens into different species). We present a scheme of relationships between species and hybrids of sections Aigeiros and Tacamahaca based on molecular genetic, morphological, and geographical data. The geographical proximity of species and, therefore, the possibility of hybridization between them appear to be more important than the affiliation of species to the same section. We speculate that sections Aigeiros and Tacamahaca are distinguished primarily on an ecological principle (plain and mountain poplars) rather than on a genetic basis. Joint analysis of sequencing data for the SDR and chloroplast genome loci allowed us to determine the ancestors of P. × petrovskoe - P. laurifolia (female tree) × P. × canadensis (male tree), and P. × rasumovskoe - P. nigra (female tree) × P. suaveolens (male tree). Thus, the efficiency of using the SDR for the study of poplars of sections Aigeiros and Tacamahaca and the prospects of its use for the investigation of species of the genus Populus were shown.

The results of the study of multiple selections in a breeding nursery when creating new soybean varieties

Relevance. At the present stage for agricultural production, the creation of new domestic competitive varieties of various plants is of paramount importance within the framework of the large-scale program of the Russian Federation for import substitution, while one of the most important and sought-after crops in Russia is soybean.Methods. The material for the research was the hybrid populations F7-F17 generations of the breeding nursery (SP), which is annually replenished with selections of individual plants from the F6 hybrid nursery.Results. An estimate of the duration of multiple selections by the pedigry method in a breeding nursery (SP) until obtaining homozygous lines is given. The analysis of the conducted studies showed that out of 29 soybean varieties of hybrid origin included in the State Register of Breeding Achievements of the Russian Federation and being tested for 2023, 13 varieties (Harmoniya, Lydia, Nega 1, MK-100, Lebedushka, Zhuravushka, Lacemaker, Cinderella, Tisey, Lyana, Olimp, Lastochka, Tatiana) (44.8%) were obtained on the basis of multiple selections F7-F9 in the breeding nursery, and the variety Persona, which is included in the State Register for 11 regions and is in demand in the Amur Region, was isolated from the hybrid population of the F17 generation. As a result of the assessment for 2020–2022. F7-F17 generations of the breeding nursery according to the duration of splitting in hybrid populations, it was found that multiple selection up to the tenth generation is most effective (F7 — 35.1%, F8 — 30.8%, F9 — 12.1%), but promising highly productive lines with economically valuable traits can also be obtained from later generations

Encyclia × tixtlensis (Orchidaceae: Laeliinae), a possible natural hybrid between E. meliosma and E. atrorubens in Guerrero, México

Encyclia × tixtlensis, a possible natural hybrid between E. atrorubens and E. meliosma recently found in the State of Guerrero, Mexico, is described and illustrated. Aspects of its possible hybrid origin are discussed, and a comparison is made with other Encyclia taxa found in the same region. The conical-piriform shape of its pseudobulbs, the straight or slightly reflexed leaves, as well as its flowers with light to dark brown sepals and petals, the lip with wide lobes, brown at its base and profusely magenta-streaked, and the column with a bending in the basal third, distinguish it from any other taxon in the genus.

Re-Analysis of the Widely Used Recombinant Murine Cytomegalovirus MCMV-m157luc Derived from the Bacmid pSM3fr Confirms Its Hybrid Nature.

Murine cytomegalovirus (MCMV), and, in particular, recombinant virus derived from MCMV-bacmid pSM3fr, is widely used as the small animal infection model for human cytomegalovirus (HCMV). We sequenced the complete genomes of MCMV strains and recombinants for quality control. However, we noticed deviances from the deposited reference sequences of MCMV-bacmid pSM3fr. This prompted us to re-analyze pSM3fr and reannotate the reference sequence, as well as that for the commonly used MCMV-m157luc reporter virus. A correct reference sequence for this frequently used pSM3fr, containing a repaired version of m129 (MCK-2) and the luciferase gene instead of ORF m157, was constructed. The new reference also contains the original bacmid sequence, and it has a hybrid origin from MCMV strains Smith and K181.

Single hybrid population but multiple parental individuals at the origin of parthenogenetic rock lizards Darevskia sapphirina and D. bendimahiensis Schmidtler, & Eiselt Darevsky (1994) endemic to the area of Lake Van in East Turkey

Among vertebrates, obligate parthenogenesis is only found in Squamata, where it always has a hybrid origin and a few lizard genera contain most of the known hybridogenous parthenogenetic taxa. Parthenogenesis thus seems to be pre-conditioned at the genus level, but it is not clear how often the encounter between two parental sexually reproducing species can result in the parthenogenetic offspring, nor whether the success of such hybridization event requires certain conditions or the specific time frame. To address this question, we studied the rock lizards of genus Darevskia, where a pair of parental species, D. valentini and D. raddei, as well as their parthenogenetic daughter species D. bendimahiensis and D. sapphirina, are found in close proximity NE of the Lake Van in East Anatolia. Using ddRAD-seq genotyping on 19 parental and 18 hybrid individuals, we found that (i) all parthenogenetic individuals from both D. bendimahiensis and D. sapphirina have a monophyletic origin tracing back to a single initial hybrid population, but their current genetic variation is geographically structured; (ii) unlike the most probable paternal ancestor, the genetically closest extant population of the maternal ancestor is not the geographically nearest one; and (iii) in the parthenogens, about 1% of loci carry multiple haplotypes, frequently differentiated by multiple substitutions. This pattern, in addition to biases in the relative frequency of haplotypes of maternal and paternal origin, does not appear compatible with a scenario of the entire parthenogenic clonal population having descended from a single pair of parental individuals. Instead, the data suggest that multiple parental individual ancestries still persist in the parthenogenetic gene pool. This supports the notion that although hybridization leading to parthenogenesis is generally rare at the level of species, it may be more common at the individual/population level once the right conditions are met.

Red and melanized focal changes in white skeletal muscle in Atlantic salmon (Salmo salar): Comparative analysis of farmed, wild and hybrid fish reared under identical conditions.

Selective breeding plays a vital role in the production of farmed Atlantic salmon and has shown success in many aspects. Still, challenges related to fish health and welfare continue to result in significant economic losses. One such challenge is red and melanized focal changes (RFC/MFC), which result from acute and chronic inflammation, respectively, in the skeletal muscle. Importantly, RFC/MFC has not been observed in wild Atlantic salmon, suggesting that both external and genetic factors may contribute to the development of inflammation. To investigate the underlying cause of RFC/MFC, we conducted a study involving 1854 Atlantic salmon of farmed, wild and hybrid origin. All fish were reared under identical conditions to minimize the influence of external factors. Throughout the production cycle, the fish was monitored for growth parameters and examined for RFC/MFC using macroscopic and histological analysis. We found no association between the experimental groups and the presence of RFC/MFC. Histological investigations revealed melano-macrophages in the soft tissue in freshwater smolt, although no macroscopic discoloration was observed. MFC showed granulomas in various stages, suggesting a complex progression of the condition. In summary, we conclude that RFC/MFC is primarily caused by external factors found in the rearing facilities of farmed Atlantic salmon.

Multiple paternally inherited chloroplast capture events associated with Taxus speciation in the Hengduan Mountains

Mountainous regions provide a multitude of habitats and opportunities for complex speciation scenarios. Hybridization leading to chloroplast capture, which can be revealed by incongruent phylogenetic trees, is one possible outcome.Four allopatric Taxus lineages (three species and an undescribed lineage) from the Hengduan Mountains, southwest China, exhibit conflicting phylogenetic relationships between nuclear and chloroplast phylogenies. Here, we use multi-omic data at the population level to investigate their historical speciation processes.Population genomic analysis based on ddRAD-seq data revealed limited contemporary inter-specific gene flow involving only populations located close to another species.In a historical context, chloroplast and nuclear data (transcriptome) consistently showed conflicting phylogenetic relationships for T. florinii and the Emei type lineage. ILS and chloroplast recombination were excluded as possible causes, and transcriptome and ddRAD-seq data revealed an absence of the mosaic nuclear genomes that characterize hybrid origin scenarios.Therefore, T. florinii appears to have originated when a lineage of T. florinii captured the T. chinensis plastid type, whereas plastid introgression in the opposite direction generated the Emei Type. All four species have distinct ecological niche based on community investigations and ecological niche analyses.We propose that the origins of both species represent very rare examples of chloroplast capture events despite the paternal cpDNA inheritance of gymnosperms. Specifically, allopatrically and/or ecologically diverged parental species experienced a rare secondary contact, subsequent hybridization and reciprocal chloroplast capture, generating two new lineages, each of which acquired a unique ecological niche. These events might have been triggered by orogenic activities of the Hengduan Mountains and an intensification of the Asian monsoon in the late Miocene, and may represent a scenario more common in these mountains than presently known.

Molecular identification of Bambusa changningensis is the natural bamboo hybrid of B. rigida × Dendrocalamus farinosus.

Bamboo is one of the fastest-growing plants commonly used in food, fibre, paper, biofuel, ornamental and medicinal industries. Natural hybridization in bamboo is rare due to its long vegetative period followed by gregarious flowering and death of the entire population. In the current study, a new bamboo species, Bambusa changningensis, shows intermediate characteristics of Dendrocalamus farinosus and B. rigida morphologically, but it is unknown whether B. changningensis is a natural hybrid. Moreover, B. changningensis has been identified as a superior variety of Sichuan Province with high pulping yield, fibre length and width. Therefore, we analyzed the morphological characteristics, DNA markers, DNA barcoding and chloroplast genomes to identify the hybrid origin of B. changningensis and possible maternal parent. We have developed the transcriptomic data for B. changningensis and mined the SSR loci. The putative parental lines and hybrid were screened for 64 SSR makers and identified that SSR14, SSR28, SSR31 and SSR34 markers showed both alleles of the parental species in B. changningensis, proving heterozygosity. Sequencing nuclear gene GBSSI partial regions and phylogenetic analysis also confirm the hybrid nature of B. changningensis. Further, we have generated the complete chloroplast genome sequence (139505 bp) of B. changningensis. By analyzing the cp genomes of both parents and B. changningensis, we identified that B. rigida might be the female parent. In conclusion, our study identified that B. changningensis is a natural hybrid, providing evidence for bamboo's natural hybridization. This is the first report on confirming a natural bamboo hybrid and its parents through SSR and chloroplast genome sequence.

No wonder, it is a hybrid. Natural hybridization between Jacobaea vulgaris and J. erucifolia revealed by molecular marker systems and its potential ecological impact.

Progressive changes in the environment are related to modifications of the habitat. Introducing exotic species, and interbreeding between species can lead to processes that in the case of rare species or small populations threatens their integrity. Given the declining trends of many populations due to increased hybridization, early recognition of hybrids becomes important in conservation management. Natural hybridization is prevalent in Jacobaea. There are many naturally occurring interspecific hybrids in this genus, including those between Jacobaea vulgaris and its relatives. Although Jacobaea erucifolia and J. vulgaris often co-occur and are considered closely related, apart from the few reports of German botanists on the existence of such hybrids, there is no information on research confirming hybridization between them. Morphologically intermediate individuals, found in the sympatric distributions of J. vulgaris and J. erucifolia, were hypothesized to be their hybrids. Two molecular marker systems (nuclear and chloroplast DNA markers) were employed to test this hypothesis and characterize putative hybrids. Nuclear and chloroplast DNA sequencing results and taxon-specific amplified fragment length polymorphism (AFLP) fragment distribution analysis confirmed the hybrid nature of all 25 putative hybrids. The AFLP patterns of most hybrids demonstrated a closer relationship to J. erucifolia, suggesting frequent backcrossing. Moreover, they showed that several individuals previously described as pure were probably also of hybrid origin, backcrosses to J. erucifolia and J. vulgaris. This study provides the first molecular confirmation that natural hybrids between J. vulgaris and J. erucifolia occur in Poland. Hybridization appeared to be bidirectional but asymmetrical with J. vulgaris as the usual maternal parent.

Molecular and morphological evidences for the hybrid origin of Kushui Rose

Molecular and morphological evidences for the hybrid origin of Kushui Rose

Comparative Pollen Morphology of the Genus Chaenomeles Lindl. (Rosaceae): Diagnostic Features and Implications for Taxonomy

The taxonomic placements of Chaenomeles Lindl. (Rosaceae) and their intrageneric species have long been controversial. This research aims to explore the palynomorphological characters of all Chaenomeles extant species in detail and to compare the results with phylogenetic relationships and the taxonomic classification scheme. The pollen morphology of 30 individuals of six taxa of Chaenomeles was investigated using both light microscopy and scanning electron microscopy. The pollens were measured, observed and statistically analyzed for 12 quantitative features and 2 qualitative ones. The study revealed that the Chaenomeles pollens are monad, tri-colporate, medium in size (P = 32.78–42.74 μm, E = 30.42–36.31 μm) and prolatespheroidal to subprolate in shape (P/E = 0.98–1.35). Based on exine ornamentation observed under SEM, two sexine sculpture types (type I—striate with microperforations, type II—striate with macroperforations) and two subtypes (twisted-striate, reticulate-striate) were recognized in the genus. Statistical analysis identified some pollen characteristics with diagnostic importance, including pollen shape, colpus dimension, length or direction of striae and diameter of perforation. These characteristics may have diagnostic and taxonomic value for the genus Chaenomeles and the family Rosaceae. An artificial key to studied species, based on pollen micromorphological attributes, is also provided. The obtained result was basically consistent with that of molecular studies published earlier. This study, for the first time, provides palynological evidence for the hybrid origin hypothesis of C. sinensis and supports the placement of this species in the monotypic genus Pseudocydonia.

Genotypical response of barley to increased cadmium content in soil

The results of a comparative evaluation of spring barley (Hordeum vulgare L.) varieties obtained by different methods on control and provocative soil background for cadmium are presented. A total of 10 varieties were studied: Rodnik Prikamya, Novichok, Dina, Zazersky 85, Triumph, Tallon (hybridization and selection); Forward, Bionic, Vitrum (cell selection); In memory of Dudin (mutagenesis). The studies were carried out in 2021 under the climatic conditions of the Kirov region. Seeds of the plants of each variety were sown in vegetation containers filled with soddy-podzolic soil. Cadmium provocative background (6.4 ± 0.5 mg/kg) was created by adding cadmium acetate to the soil. The average yield of barley varieties in the control (soil background without cadmium) was 279 g/m2; against a provocative background – 216 g/m2. Under the conditions of cadmium stress, the yield of hybrids decreased compared to the control by 12.2 %, regenerants – by 29.6 %, mutant – by 42.4 %. Among the studied varieties, the Bionic variety, which has a regenerated origin, showed a consistently high yield both on the control (334 g/m2) and cadmium background (263 g/m2). Productive bushiness of hybrid barley varieties against the control background varied from 2.8 to 4.1; in regenerants – from 3.4 to 4.8; mutant varieties – 4.3 pieces. Under the conditions of cadmium stress, productive bushiness decreased by an average of 2.7 – in hybrids; for 3.4 – for regenerants, for 2.6 pieces – a mutant. Bionic, regardless of the soil background, compared with other varieties, had the highest productive bushiness. Significant differences in the content of polyphenols in the grain of the studied varieties on the control and provocation soil background for cadmium were not revealed. Under the conditions of cadmium stress, a decrease in the content of flavonoids in grain was noted, as well as the accumulation of cadmium (0.29–0.92 mg/kg). Varieties of hybrid origin showed the ability to accumulate cadmium in grain to a greater extent.

Genome-wide analysis highlights genetic admixture in exotic germplasm resources of Eucalyptus and unexpected ancestral genomic composition of interspecific hybrids.

Eucalyptus is an economically important genus comprising more than 890 species in different subgenera and sections. Approximately twenty species of subgenus Symphyomyrtus account for 95% of the world's planted eucalypts. Discrimination of closely related eucalypt taxa is challenging, consistent with their recent phylogenetic divergence and occasional hybridization in nature. Admixture, misclassification or mislabeling of Eucalyptus germplasm resources maintained as exotics have been suggested, although no reports are available. Moreover, hybrids with increased productivity and traits complementarity are planted worldwide, but little is known about their actual genomic ancestry. In this study we examined a set of 440 trees of 16 different Eucalyptus species and 44 interspecific hybrids of multi-species origin conserved in germplasm banks in Brazil. We used genome-wide SNP data to evaluate the agreement between the alleged phylogenetic classification of species and provenances as registered in their historical records, and their observed genetic clustering derived from SNP data. Genetic structure analyses correctly assigned each of the 16 species to a different cluster although the PCA positioning of E. longirostrata was inconsistent with its current taxonomy. Admixture was present for closely related species' materials derived from local germplasm banks, indicating unintended hybridization following germplasm introduction. Provenances could be discriminated for some species, indicating that SNP-based discrimination was directly proportional to geographical distance, consistent with an isolation-by-distance model. SNP-based genomic ancestry analysis showed that the majority of the hybrids displayed realized genomic composition deviating from the expected ones based on their pedigree records, consistent with admixture in their parents and pervasive genome-wide directional selection toward the fast-growing E. grandis genome. SNP data in support of tree breeding provide precise germplasm identity verification, and allow breeders to objectively recognize the actual ancestral origin of superior hybrids to more realistically guide the program toward the development of the desired genetic combinations.

Torymus sinensis and its close relatives in Europe: a multilocus phylogeny, detailed morphological analysis, and identification key

The introduction of the biological control agent Torymus sinensis Kamijo (Hymenoptera, Chalcidoidea, Torymidae) to control the populations of the chestnut gall wasp Dryocosmus kuriphilus Yasumatsu (Hymenoptera, Cynipidae) is considered one of the successful programs in biological control. The species was involved in interspecific hybridisation in Japan and the specimens imported into Europe were derived from this hybrid lineage, showing signs of introgression. The discovery of mitochondrial haplotypes or possible Enolase haplotypes from T. beneficus or of specimens with shorter ovipositor does not necessarily imply that T. beneficus is present in Europe, only that the European specimens are of hybrid origin. Of the native European Torymus species associated with D. kuriphilus, the molecular and morphometric results indicate Torymus notatus (Walker) as the closest species to T. sinensis. The two are part of the same species-group (cyaneus group), are nested together in the multivariate ratio analysis and are the closest genetically based on all three nuclear markers: Enolase (1.5% divergence), Wingless (2%) and ITS2 (13%). However, on the mitochondrial marker COI the closest species is Torymus rubi (Schrank) at 9.9% divergence. As such, T. notatus is the most likely candidate for accidental interspecific hybridisation if this is to happen in Europe. We provide an illustrated identification key for the European species of Torymus associated with D. kuriphilus, an important but lacking tool for biological control programs.

Haplotype-resolved, chromosome-level assembly of white clover (Trifolium repens L., Fabaceae).

White clover (Trifolium repens L.; Fabaceae) is an important forage and cover crop in agricultural pastures around the world and is increasingly used in evolutionary ecology and genetics to understand the genetic basis of adaptation. Historically, improvements in white clover breeding practices and assessments of genetic variation in nature have been hampered by a lack of high-quality genomic resources for this species, owing in part to its high heterozygosity and allotetraploid hybrid origin. Here, we use PacBio HiFi and chromosome conformation capture (Omni-C) technologies to generate a chromosome-level, haplotype-resolved genome assembly for white clover totaling 998 Mbp (scaffold N50 = 59.3 Mbp) and 1 Gbp (scaffold N50 = 58.6 Mbp) for haplotypes 1 and 2, respectively, with each haplotype arranged into 16 chromosomes (8 per subgenome). We additionally provide a functionally annotated haploid mapping assembly (968 Mbp, scaffold N50 = 59.9 Mbp), which drastically improves on the existing reference assembly in both contiguity and assembly accuracy. We annotated 78,174 protein-coding genes, resulting in protein BUSCO completeness scores of 99.6% and 99.3% against the embryophyta_odb10 and fabales_odb10 lineage datasets, respectively.

Phylogenetic, cytogenetic and morphological evidences are critical for recognizing a new genus: Valdesiana, an Iberian intergeneric allopolyploid between Schenkia and Exaculum

The present taxonomic status of Schenkia elegans, endemism recently described in the Iberian Peninsula, and its relationship with the sympatric and the nearest morphological species Schenkia spicata and Exaculum pusillum is revaluated. Different kinds of evidence based on plant morphology, ploidy estimation by flow cytometry, karyotype characterisation, and phylogenetic data have been analysed. Two maternally inherited plastid DNA regions (trnL intron and trnL-F spacer) and biparentally inherited nuclear ribosomal DNA sequence region (nrDNA ITS) have been used. Comparative multivariate analyses show an intermediate morphology of the S. elegans plants between the other two species studied. Flow cytometry and karyotype analyses in S. elegans point to an allopolyploid origin, with the latter constituted by a mixture of those of the diploids S. spicata and E. pusillum. Phylogenetic analyses based on plastid and nuclear DNA regions cluster S. elegans in two different clades, those of S. spicata and E. pusillum, suggesting a possible hybrid origin of S. elegans between both species, acting as maternal or paternal progenitors. In consequence, taking in consideration the taxonomic relationships among genera (Exaculum, Schenkia and the closely related genus Zeltnera found in America), a monotypic genus Valdesiana gen. nov. is proposed to accommodate the allopolyploid species, combined as V. elegans, for which immediate conservation measures must be evaluated.

Stromatolite-like Structures Within Microbially Laminated Sandstones of the Paleoarchean Moodies Group, Barberton Greenstone Belt, South Africa.

We report abundant small calcareous mounds associated with fossilized kerogenous microbial mats in tidal-facies sandstones of the predominantly siliciclastic Moodies Group (ca. 3.22 Ga) of the Barberton Greenstone Belt (BGB), South Africa and Eswatini. Most of the bulbous, internally microlaminated mounds are several centimeters in diameter and formed at the sediment-water interface contemporaneously with sedimentation. They originally consisted of Fe-Mg-Mn carbonate, which is now largely silicified; subtle internal compositional laminations are composed of organic matter and sericite. Their presence for >6 km along strike, their restriction to the inferred photic zone, and the internal structure suggest that mineral precipitation was induced by photosynthetic microorganisms. Similar calcareous mounds in this unit also occur within and on top of fluid-escape conduits, suggesting that carbonate precipitation may either have occurred abiogenically or involved chemotrophic metabolism(s) utilizing the oxidation of organic matter, methane, or hydrogen, the latter possibly generated by serpentinization of underlying ultramafic rocks. Alternatively or additionally, carbonate may have precipitated abiotically where heated subsurface fluids, sourced by the intrusion of a major Moodies-age sill, reached the tidal flats. In summary, precipitation mechanisms may have been variable; the calcareous mounds may represent "hybrid carbonates" that may have originated from the small-scale overlap of bioinduced and abiotic processes in space and time. Significantly, the widespread occurrence of these stromatolite-like structures in a fully siliciclastic, high-energy tidal setting broadens search criteria in the search for life on Mars while their possible hybrid origin challenges our ability to unambiguously identify a biogenic component.