Plant Diversification Research Articles

Land Conservation and The Potential Goal for Food Security in Urban City

Population growth and increasing demand for land for urban development have led to the conversion of agricultural land. Land conversion harms the reduction of agricultural areas and indirectly affects food availability, so efforts are needed to preserve it. The study aims to obtain the availability of paddy fields and the conservation strategies. Evaluation of land use change and availability was analyzed by high-resolution SPOT 6/7 satellite imagery data, slope maps, soil type maps, sub-district administrative boundaries maps, raw rice field maps, spatial pattern planning maps, climate data, and criteria for land suitability for food crops. The strategy of conservation of paddy fields based on the wisdom of Subak (Balinese cultural base irrigation system for paddy fields) was analyzed by SWOT. The analysis showed that the converted land areas were 78.5 Ha. The available paddy fields that needed to be conserved were 895.02 Ha, consisting of a moderate suitability class of 556.74 Ha and a very suitable suitability level of 338.28 Ha. The strategy for conservation of paddy fields based on Subak wisdom must be implemented through 1) Developing tourist attractions based on Subak agricultural activities and rituals, 2) Developing a network of cooperation with the government and business people, 3) Implementing strict Subak rules (awig-awig), 4) Encouraging Subak to be more business-oriented through plant diversification that has market prospects.

Terrestrialization in the Ordovician

Abstract This contribution reviews the evidence for terrestrial organisms during the Ordovician (microbial, land plant, fungal, animal) and for the nature of the terrestrial biota. The evidence regarding the origin and early diversification of land plants combines information from both fossils and living organisms. Extant plants can be utilized in: (1) phylogenetic analyses to provide evidence for the nature of the algal–land plant transition and the characteristics of the most basal land plants; (2) evolutionary developmental biology studies of the characters that enabled the invasion of the land; (3) molecular clock analysis to provide evidence regarding timing of the origin and diversification of land plants. We conclude that the Ordovician was a critical period during the terrestrialization of planet Earth that witnessed the transition from a microbial terrestrial biota to one dominated by a vegetation of the most basal land plants.

Bioactive Extracts: Strategies to Generate Diversified Natural Product- Like Libraries

Abstract: Natural products have stimulated the interest of chemists owing to their abundant structural diversity and complexity. Indeed, natural products have performed an essential role, particularly in the cure of cancerous and infectious diseases, thereby providing medicinal researchers with several unexplored chemotypes for the innovation of new drugs. Fusion of chemical derivatization and combinatorial synthesis forms the basis of the concept of chemo diversification of plants. Diverse libraries of natural product analogs are constructed through existing biological and chemical approaches using unique schemes to expand natural product frameworks. This review aims to present several approaches employed to offer innovative opportunities to synthesize NP-inspired compound libraries. Reactive molecular fragments present in most natural products are chemically converted to chemically engineered extracts (CEEs) or semisynthetic compounds constituting distinct libraries. Bio-guided isolation for natural products required vital tools like reverse phase chromatography and bioautographic assays. Different established strategies from DTS, BIOS, CtD, FOS, FBDD to late-stage diversification facilitate the expansion of molecules with physicochemical properties. In particular, fragment-like natural products with novel skeletons may be used as preliminary points for chemical biology and medicinal chemistry programs with great capacity. In this review, we sum up how NPs have proven fruitful for the novel methodologies responsible for the diversification of complex natural products; therefore, it is worth going over the upcoming integration of natural products with combinatorial chemistry.

Hexicladia, a new genus of the Cisuralian conifer from Hexi Corridor, China

Enriching our knowledge of Paleozoic conifers helps our understanding of plant diversification and climate change in this period. Here we report a compression conifer with well-preserved leaf twigs and seed cones discovered in the Cisuralian Shanxi Formation in Yongchang, Gansu Province, northwest China. The conifer was identified as a new genus, Hexicladia (H. yongchangensis gen. et sp. nov.), according to detailed morphological comparisons of vegetative and reproductive organs with related fossil genera of Paleozoic conifers. The vegetative shoots have helically-arranged ascending branches. The leaves are spirally arranged and broadly attached. The seed cones are terminal and erect, with several bract-scale complexes around the cone axis. The new fossil is assigned to the Voltziales, based on its whole architecture, and its similarities to some “walchian” conifers. Nevertheless, the discovery of Hexicladia gen. nov. adds to our knowledge of Paleozoic conifers, and reveals that conifers had already evolved complex features in the early Permian.

Polyploidy: its consequences and enabling role in plant diversification and evolution.

Most, if not all, green plant (Virdiplantae) species including angiosperms and ferns are polyploids themselves or have ancient polyploid or whole genome duplication signatures in their genomes. Polyploids are not only restricted to our major crop species such as wheat, maize, potato and the brassicas, but also occur frequently in wild species and natural habitats. Polyploidy has thus been viewed as a major driver in evolution, and its influence on genome and chromosome evolution has been at the centre of many investigations. Mechanistic models of the newly structured genomes are being developed that incorporate aspects of sequence evolution or turnover (low-copy genes and regulatory sequences, as well as repetitive DNAs), modification of gene functions, the re-establishment of control of genes with multiple copies, and often meiotic chromosome pairing, recombination and restoration of fertility. World-wide interest in how green plants have evolved under different conditions - whether in small, isolated populations, or globally - suggests that gaining further insight into the contribution of polyploidy to plant speciation and adaptation to environmental changes is greatly needed. Forward-looking research and modelling, based on cytogenetics, expression studies, and genomics or genome sequencing analyses, discussed in this Special Issue of the Annals of Botany, consider how new polyploids behave and the pathways available for genome evolution. They address fundamental questions about the advantages and disadvantages of polyploidy, the consequences for evolution and speciation, and applied questions regarding the spread of polyploids in the environment and challenges in breeding and exploitation of wild relatives through introgression or resynthesis of polyploids. Chromosome number, genome size, repetitive DNA sequences, genes and regulatory sequences and their expression evolve following polyploidy - generating diversity and possible novel traits and enabling species diversification. There is the potential for ever more polyploids in natural, managed and disturbed environments under changing climates and new stresses.

Biotic and abiotic factors in promoting the starting point of hybridization in the Neotropical flora: implications for conservation in a changing world

AbstractCoevolution between floral traits and specific pollination behaviour is a significant evolutionary force in angiosperm diversification. However, hybridization is also reported to occur between plants with specialist pollination syndromes. Understanding the role of pollinators in plant diversification is crucial, especially in megadiverse regions, such as the Neotropics. In this review, we examine plant hybridization studies in the Neotropics with the aim of providing a perspective on biotic and abiotic factors starting hybrid zone formation. The Pleistocene was the most widely cited time for the occurrence of hybridization facilitated by geographical range shifts, but time-calibrated analyses are needed to recover a more realistic scenario. Our synthesis of hybridization and pollination systems suggested that specialist and generalist pollinators were associated with the starting point of hybridization in the Neotropical flora. Bees and hummingbirds are most likely to be the primary vectors of interspecific gene flow, and even sporadic visits by bees or other generalist pollinators could allow the formation of a new hybrid zone. We highlight that seed and pollen dispersal vectors should be included in an integrative discussion on hybridization in the Neotropical flora. We also provide a preliminary map of hybrid zones in the Neotropics, including Brazilian vegetation cover and losses in the last 30 years, with the aim of encouraging research into human-driven anthropogenic changes and formation and/or shift of hybrid zones through time.

Pan-mitogenomics reveals the genetic basis of cytonuclear conflicts in citrus hybridization, domestication, and diversification

Although interactions between the cytoplasmic and nuclear genomes occurred during diversification of many plants, the evolutionary conflicts due to cytonuclear interactions are poorly understood in crop breeding. Here, we constructed a pan-mitogenome and identified chimeric open reading frames (ORFs) generated by extensive structural variations (SVs). Meanwhile, short reads from 184 accessions of citrus species were combined to construct three variation maps for the nuclear, mitochondrial, and chloroplast genomes. The population genomic data showed discordant topologies between the cytoplasmic and nuclear genomes because of differences in mutation rates and levels of heteroplasmy from paternal leakage. An analysis of species-specific SVs indicated that mitochondrial heteroplasmy was common and that chloroplast heteroplasmy was undetectable. Interestingly, we found a prominent divergence in the mitogenomes and the highest genetic load in the, which may provide the basis for cytoplasmic male sterility (CMS) and thus influence the reshuffling of the cytoplasmic and nuclear genomes during hybridization. Using cytoplasmic replacement experiments, we identified a type of species-specific CMS in mandarin related to two chimeric mitochondrial genes. Our analyses indicate that cytoplasmic genomes from mandarin have rarely been maintained in hybrids and that paternal leakage produced very low levels of mitochondrial heteroplasmy in mandarin. A genome-wide association study (GWAS) provided evidence for three nuclear genes that encode pentatricopeptide repeat (PPR) proteins contributing to the cytonuclear interactions in the Citrus genus. Our study demonstrates the occurrence of evolutionary conflicts between cytoplasmic and nuclear genomes in citrus and has important implications for genetics and breeding.

Unusual patterns of hybridization involving two alpine Salvia species: Absence of both F1 and backcrossed hybrids.

Natural hybridization plays an important role in speciation; however, we still know little about the mechanisms underlying the early stages of hybrid speciation. Hybrid zones are commonly dominated by F1s, or backcrosses, which impedes further speciation. In the present study, morphological traits and double digest restriction-site associated DNA sequencing (ddRAD-seq) data have been used to confirm natural hybridization between Salvia flava and S. castanea, the first case of identification of natural hybridization using combined phenotypic and molecular evidence in the East Asian clade of Salvia. We further examined several reproductive barriers in both pre-zygotic and post-zygotic reproductive stages to clarify the causes and consequences of the hybridization pattern. Our results revealed that reproductive isolation between the two species was strong despite the occurrence of hybridization. Interestingly, we found that most of the hybrids were likely to be F2s. This is a very unusual pattern of hybridization, and has rarely been reported before. The prevalence of geitonogamy within these self-compatible hybrids due to short distance foraging by pollinators might explain the origin of this unusual pattern. F2s can self-breed and develop further, therefore, we might be witnessing the early stages of hybrid speciation. Our study provides a new case for understanding the diversification of plants on the Qinghai-Tibet Plateau.

Maintaining remnant vegetation along with plant diversification in vineyards is optimal for conserving arthropods in an agricultural mosaic in a biodiversity-rich region

Maintaining remnant vegetation along with plant diversification in vineyards is optimal for conserving arthropods in an agricultural mosaic in a biodiversity-rich region

Variación interespecífica de ensambles de polinizadores en Nierembergia (Solanaceae) en relación con la localización geográfica y la variación fenotípica de las flores

Understanding how the interactions of related plant species with pollinators vary on a spatial scale provides the opportunity to establish links between macroevolutionary patterns and microevolutionary processes, as well as to approach the mechanisms underlying plant diversification. In this work, we explore the variation in pollinator assemblages of 15 species and varieties of Nierembergia (Solanaceae) across the distribution range of the genus in Argentina, in relation to variation in floral phenotype and geographic location. By field observations, morphometric measurements of flowers and comparative phylogenetic methods, pollinator assemblages and flowers of Nierembergia taxa were characterized and compared, and the association between pollinator assemblage composition, geographic location, floral morphology and phylogenetic relationships was evaluated. 13 species of oil-collecting bees were recorded as pollinators. The assemblage composition was strongly associated with geographic location, that is, Nierembergia taxa in nearby areas had greater similarity in their pollinator assemblages than geographically distant taxa. This pattern was not associated with phylogenetic relationships among taxa, except for a group of high mountain species in northwestern Argentina. On the other hand, interspecific variation was found in the floral phenotype, mainly in the corolla and the oil-producing gland size. However, Nierembergia taxa with similar floral phenotypes did not share the composition of the pollinator assemblage, as expected. In conclusion, we found a mixed macroevolutionary pattern in which some phylogenetically distant Nierembergia taxa converge geographically in the composition of pollinator assemblages, while this attribute is conserved in a phylogenetic clade. This pattern suggests that the role of pollinators in Nierembergia diversification is more complex than previously thought.

Increased ACS Enzyme Dosage Causes Initiation of Climacteric Ethylene Production in Tomato.

Fruits of wild tomato species show different ethylene-dependent ripening characteristics, such as variations in fruit color and whether they exhibit a climacteric or nonclimacteric ripening transition. 1-Aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) and ACC oxidase (ACO) are key enzymes in the ethylene biosynthetic pathway encoded by multigene families. Gene duplication is a primary driver of plant diversification and angiosperm evolution. Here, interspecific variations in the molecular regulation of ethylene biosynthesis and perception during fruit ripening in domesticated and wild tomatoes were investigated. Results showed that the activated ACS genes were increased in number in red-ripe tomato fruits than in green-ripe tomato fruits; therefore, elevated dosage of ACS enzyme promoted ripening ethylene production. Results showed that the expression of three ACS isogenes ACS1A, ACS2, and ACS4, which are involved in autocatalytic ethylene production, was higher in red-ripe tomato fruits than in green-ripe tomato fruits. Elevated ACS enzyme dosage promoted ethylene production, which corresponded to the climacteric response of red-ripe tomato fruits. The data suggest that autoinhibitory ethylene production is common to all tomato species, while autocatalytic ethylene production is specific to red-ripe species. The essential regulators Non-ripening (NOR) and Ripening-Inhibitor (RIN) have experienced gene activation and overlapped with increasing ACS enzyme dosage. These complex levels of transcript regulation link higher ethylene production with spatiotemporal modulation of gene expression in red-ripe tomato species. Taken together, this study shows that bursts in ethylene production that accompany fruit color changes in red-ripe tomatoes are likely to be an evolutionary adaptation for seed dispersal.

Differences in pseudogene evolution contributed to the contrasting flavors of turnip and Chiifu, two Brassica rapa subspecies

Pseudogenes are important resources for investigation of genome evolution and genomic diversity because they are nonfunctional but have regulatory effects that influence plant adaptation and diversification. However, few systematic comparative analyses of pseudogenes in closely related species have been conducted. Here, we present a turnip (Brassica rapa ssp. rapa) genome sequence and characterize pseudogenes among diploid Brassica species/subspecies. The results revealed that the number of pseudogenes was greatest in Brassica oleracea (CC genome), followed by B. rapa (AA genome) and then Brassica nigra (BB genome), implying that pseudogene differences emerged after species differentiation. In Brassica AA genomes, pseudogenes were distributed asymmetrically on chromosomes because of numerous chromosomal insertions/rearrangements, which contributed to the diversity among subspecies. Pseudogene differences among subspecies were reflected in the flavor-related glucosinolate (GSL) pathway. Specifically, turnip had the highest content of pungent substances, probably because of expansion of the methylthioalkylmalate synthase-encoding gene family in turnips; these genes were converted into pseudogenes in B. rapa ssp. pekinensis (Chiifu). RNA interference-based silencing of the gene encoding 2-oxoglutarate-dependent dioxygenase 2, which is also associated with flavor and anticancer substances in the GSL pathway, resulted in increased abundance of anticancer compounds and decreased pungency of turnip and Chiifu. These findings revealed that pseudogene differences between turnip and Chiifu influenced the evolution of flavor-associated GSL metabolism-related genes, ultimately resulting in the different flavors of turnip and Chiifu.

Spatial distribution of species richness and endemism of Solanum (Solanaceae) in Mexico

The spatial distribution of the species richness is not aleatory. It responds to evolutionary, geographical, and climatic events, and it is important to establish biodiversity management and conservation priorities. The mountainous zones around the globe have been identified as centers of plant diversification. In Mexico, the Mexican Transition Zone (MTZ) which comprises the main mountainous chains is recognized as an area of high species richness and endemism. The genus Solanum (Solanaceae) includes 1228 accepted species distributed all over the world, but with centers of species richness and endemism in the neotropical mountains. Based on patterns observed in geographical distribution of Mexican biodiversity, we expect the MTZ to host the highest species richness and endemism of Solanum. Here, we evaluated the spatial distribution of the species richness and endemism of Solanum in Mexico. For that purpose, we used 10043 unique georeferenced records obtained from herbarium specimens, specimens cited in literature and electronic databases. Then, we quantified species richness and endemism using biogeographical regions and provinces, a grid-cell of 50 × 50 km, political division, vegetation types, elevational, latitudinal, as well as longitudinal gradients. In addition, we analyzed endemism through weighted endemism and corrected weighted endemism. In Mexico, there were 134 species of Solanum including 43 endemics. The species richness and endemism were concentrated along the MTZ, specifically in the Chiapas Highlands, Sierra Madre del Sur (SMS), and Transmexican Volcanic Belt (TVB). Eight cells containing 63.43% of the species were obtained in the grid-cell analysis. The species richness distribution assessment by vegetation type, elevation, and political division confirmed the MTZ as the richest region. Likewise, the endemism was found along the MTZ in the Sierra Madre Oriental, SMS, TVB as well as in Chihuahuan Desert. Complex geological and paleoclimatic history, irregular topography, current climate diversity, dispersal, and persistence influenced these patterns. Lastly, we confirmed the remarkable importance of the MTZ as a center of origin, diversification and endemism of Mexican plants, using one of the most representative genera in Mexico.

Plant Diversification with Biopesticide Application in the Production of Cucumber (Cucumis sativus Linn.) under Carmen, Davao del Norte Conditions

The cucumber is one of the most important vegetable crops in the world regarding its nutrient composition and uses. However, this crop is also very susceptible to pest infestations that lead to significant yield loss. Therefore, this study was designed to investigate the effects of intercropping as a pest management approach in cucumbers. Results revealed that intercropping Zinnia flower with oriental herbal nutrient application significantly reduces the incidence of many important pests such as aphids, whiteflies, and cucurbit leaf beetles. On the other hand, intercropping the Zinnia flower plus the application of OHN was also found to increase the number of natural enemies in cucumber, such as parasitoids and ladybird beetles. It is therefore concluded that intercropping flowers in tandem with biopesticide can be a promising pest management strategy to minimize the dependence on synthetic insecticides. Further research must be carried out in this line of study to gain more insights and provide more scientific evidence supporting intercropping as a very important strategy and component in pest management programs. Keywords : Arthropod diversity, habitat modification, intercropping, pest management, vegetable crop

Climate windows of opportunity for plant expansion during the Phanerozoic

Earth’s long-term climate may have profoundly influenced plant evolution. Local climatic factors, including water availability, light, and temperature, play a key role in plant physiology and growth, and have fluctuated substantially over geological time. However, the impact of these key climate variables on global plant biomass across the Phanerozoic has not yet been established. Linking climate and dynamic vegetation modelling, we identify two key ‘windows of opportunity’ during the Ordovician and Jurassic-Paleogene capable of supporting dramatic expansions of potential plant biomass. These conditions are driven by continental dispersion, paleolatitude of continental area and a lack of glaciation, allowing for an intense hydrological cycle and greater water availability. These windows coincide with the initial expansion of land plants and the later angiosperm radiation. Our findings suggest that the timing and expansion of habitable space for plants played an important role in plant evolution and diversification.

Fruits of Firmiana and Craigia (Malvaceae) from the Eocene of the Central Tibetan Plateau with emphasis on biogeographic history

AbstractThe fossil record evidences an old origin and diversification of Malvaceae in the Northern Hemisphere. The central Tibetan Plateau was at a low elevation with a monsoon influence during the Eocene, allowing the development of a subtropical flora containing Malvaceae. The taxonomic study of fossils from the Eocene of what is now the Tibetan Plateau is still ongoing. Malvaceae fossils from the Eocene Jianglang flora, are attributed to sub‐families Tilioideae and Sterculioideae, and are compared with modern species. A new specimen of Firmiana is described based on a fruit valve with a pinnate venation, the secondary veins starting at the ventral suture and reaching the midvein, and the seeds attached at the proximal part of the ventral suture. This specimen represents the earliest known occurrence of the genus. A new occurrence of Craigia is also reported based on detached membranous valves of a fruit capsule with a prominent fusiform locular area and radiating venation. Based on the fossil record of Firmiana and its modern distribution, we infer that the genus may have originated in East Asia and subsequently diversified in South China and Southeast Asia. The new occurrence of Craigia indicates that the genus was distributed in humid areas in South, Southwest and North China during the Eocene. Both fossil records evidence the important role that the Tibetan region played in the diversification of plants in East and Southeast Asia.

Flexible drought deciduousness in a neotropical understory herb.

PremiseAdaptive divergence across environmental gradients is a key driver of speciation. Precipitation seasonality gradients are common in the tropics, yet drought adaptation is nearly unexplored in neotropical understory herbs. Here, we examined two recently diverged neotropical spiral gingers, one adapted to seasonal drought and one reliant on perennial water, to uncover the basis of drought adaptation.MethodsWe combined ecophysiological trait measurements in the field and greenhouse with experimental and observational assessments of real‐time drought response to determine how Costus villosissimus (Costaceae) differs from C. allenii to achieve drought adaptation.ResultsWe found that drought‐adapted C. villosissimus has several characteristics indicating flexible dehydration avoidance via semi‐drought‐deciduousness and a fast economic strategy. Although the two species do not differ in water‐use efficiency, C. villosissimus has a more rapid growth rate, lower leaf mass per area, lower stem density, higher leaf nitrogen, and a strong trend of greater light‐saturated photosynthetic rates. These fast economic strategy traits align with both field‐based observations and experimental dry‐down results. During drought, C. villosissimus displays facultative drought‐deciduousness, losing lower leaves during the dry season and rapidly growing new leaves in the wet season.ConclusionsWe revealed a drought adaptation strategy that has not, to our knowledge, previously been documented in tropical herbs. This divergent drought adaptation evolved recently and is an important component of reproductive isolation between C. villosissimus and C. allenii, indicating that adaptive shifts to survive seasonal drought may be an underappreciated axis of neotropical understory plant diversification.

The strength of reproductive isolating barriers in seed plants: Insights from studies quantifying premating and postmating reproductive barriers over the past 15 years.

Speciation is driven by the evolution of reproductive isolating barriers that reduce, and ultimately prevent, substantial gene flow between lineages. Despite its central role in evolutionary biology, the process can be difficult to study because it proceeds differently among groups and may occur over long timescales. Due to this complexity, we typically rely on generalizations of empirical data to describe and understand the process. Previous reviews of reproductive isolation (RI) in flowering plants have suggested that prezygotic or extrinsic barriers generally have a stronger effect on reducing gene flow compared to postzygotic or intrinsic barriers. Past conclusions have rested on relatively few empirical estimates of RI; however, RI data have become increasingly abundant over the past 15 years. We analyzed data from recent studies quantifying multiple pre- and postmating barriers in plants and compared the strengths of isolating barriers across 89 taxa pairs using standardized RI metrics. Individual prezygotic barriers were on average stronger than individual postzygotic barriers, and the total strength of prezygotic RI was approximately twice that of postzygotic RI. These findings corroborate that ecological divergence and extrinsic factors, as opposed to solely the accumulation of genetic incompatibilities, are important to speciation and the maintenance of species boundaries in plants. Despite an emphasis in the literature on asymmetric postmating and postzygotic RI, we found that prezygotic barriers acted equally asymmetrically. Overall, substantial variability in the strengths of 12 isolating barriers highlights the great diversity of mechanisms that contribute to plant diversification.

Rapid preservation of Jehol Biota in Northeast China from high precision 40Ar/39Ar geochronology

In Liaoning Province, Northeastern China, the Early Cretaceous Jehol Biota records significant evolution and radiation of fauna in terms of diversity, abundance and complexity. The alluvial-to-fluvial Lujiatun and lacustrine Jianshangou beds of the lower Yixian Formation yield exceptionally well-preserved three-dimensional and articulated dinosaur and mammal fossils, and two-dimensional primitive birds/feathered dinosaurs, respectively. Published 40Ar/39Ar ages for the two fossil beds have uncertainties of ± 0.4 to 1.0 Ma (± 2σ analytical uncertainty), and these reflect the measurement of large, and potentially heterogeneous, populations of feldspar crystals. More precise constraints on the timing and duration of biological radiation recorded by this sequence can further quantify evolutionary patterns and rates of diversification of important Early Cretaceous animals and plants. Single crystal 40Ar/39Ar fusion experiments on sanidine from intercalated ash beds yield dates that constrain the deposition of the Jianshangou and Lujiatun fossil beds to between 125.374 ± 0.085 and 125.572 ± 0.120 Ma, and 125.541 ± 0.099 and 125.793 ± 0.127 Ma, respectively. These ages indicate that the lower part of Jianshangou fossil bed was deposited nearly contemporaneously with the Lujiatun fossil bed. Thus, mass mortality events reflected by dinosaur fossil concentrations in the Lujiatun fossil bed and feathered dinosaur/primitive bird fossils in the Jianshangou fossil bed were nearly coeval and short-lived. These 40Ar/39Ar ages, combined with astrochronologic and paleomagnetic results from the lacustrine sediments in the Jianshangou fossil bed, not only refine the duration and rapid radiation of primitive birds and feathered dinosaurs in the deposit, but also suggest that the distribution of magnetic polarity chron boundaries within the Barremian stage in the current geologic time scale (GTS 2020) requires a revision.

The evolutionary history of Cardamine bulbifera shows a successful rapid postglacial Eurasian range expansion in the absence of sexual reproduction.

Sexual reproduction is known to drive plant diversification and adaptation. Here we investigate the evolutionary history and spatiotemporal origin of a dodecaploid (2n = 12x = 96) Eurasian deciduous woodland species, Cardamine bulbifera, which reproduces and spreads via vegetative bulb-like structures only. The species has been among the most successful range-expanding understorey woodland plants in Europe, which raises the question of the genetic architecture of its gene pool, since its hexaploid (2n = 6x = 48) but putatively outcrossing closest relative, C. quinquefolia, displays a smaller distribution range in Eastern Europe towards the Caucasus region. Cardamine bulbifera belongs to a small monophyletic clade of four species comprising also C. abchasica (2n = 2x = 16) and C. bipinnata (unknown ploidy) from the Caucasus region. We sequenced the genomes of the two polyploids and their two putative ancestors using Illumina short-read sequencing technology (×7-8 coverage). Covering the entire distribution range, genomic data were generated for 67 samples of the two polyploids (51 samples of C. bulbifera, 16 samples of C. quinquefolia) and 6 samples of the putative diploid taxa (4 samples of C. abchasica, 2 samples of C. bipinnata) to unravel the evolutionary origin of the polyploid taxa using phylogenetic reconstructions of biparentally and maternally inherited genetic sequence data. Ploidy levels of C. bulbifera and C. quinquefolia were analysed by comparative chromosome painting. We used genetic assignment analysis (STRUCTURE) and approximate Bayesian computation (ABC) modelling to test whether C. bulbifera represents genetically differentiated lineages and addressed the hypothesis of its hybrid origin. Comparative ecological modelling was applied to unravel possible niche differentiation among the two polyploid species. Cardamine bulbifera was shown to be a non-hybridogenous, auto-dodecaploid taxon of early Pleistocene origin, but with a history of past gene flow with its hexaploid sister species C. quinquefolia, likely during the last glacial maximum in shared refuge areas in Eastern Europe towards Western Turkey and the Crimean Peninsula region. The diploid Caucasian endemic C. abchasica is considered an ancestral species, which also provides evidence for the origin of the species complex in the Caucasus region. Cardamine bulbifera successfully expanded its distribution range postglacially towards Central and Western Europe accompanied by a transition to exclusively vegetative propagation. A transition to vegetative propagation in C. bulbifera is hypothesized as the major innovation to rapidly expand its distribution range following postglacially progressing woodland vegetation throughout Europe. Preceding and introgressive gene flow from its sister species C. quinquefolia in the joint refuge area is documented. This transition and ecological differentiation may have been triggered by preceding introgressive gene flow from its sister species in the joint East European refuge areas.