Comparative plastome analysis of the sister genera Ceratocephala and Myosurus (Ranunculaceae) reveals signals of adaptive evolution to arid and aquatic environments.

BACKGROUND: Expansion and contraction of inverted repeats can cause considerable variation of plastid genomes (plastomes) in angiosperms. However, little is known about whether structural variations of plastomes are associated with adaptation to or occupancy of new environments. Moreover, adaptive evolution of angiosperm plastid genes remains poorly understood. Here, we sequenced the complete plastomes for four species of xerophytic Ceratocephala and hydrophytic Myosurus, as well as Ficaria verna. By an integration of phylogenomic, comparative genomic, and selection pressure analyses, we investigated evolutionary patterns of plastomes in Ranunculeae and their relationships with adaptation to dry and aquatic habitats. RESULTS: Owing to the significant contraction of the boundary of IRA/LSC towards the IRA, plastome sizes and IR lengths of Myosurus and Ceratocephala are smaller within Ranunculeae. Compared to other Ranunculeae, the Myosurus plastome lost clpP and rps16, one copy of rpl2 and rpl23, and one intron of rpoC1 and rpl16, and the Ceratocephala plastome added an infA gene and lost one copy of rpl2 and two introns of clpP. A total of 11 plastid genes (14%) showed positive selection, two genes common to Myosurus and Ceratocephala, seven in Ceratocephala only, and two in Myosurus only. Four genes showed strong signals of episodic positive selection. The rps7 gene of Ceratocephala and the rpl32 and ycf4 genes of Myosurus showed an increase in the rate of variation close to 3.3 Ma. CONCLUSIONS: The plastomic structure variations as well as the positive selection of two plastid genes might be related to the colonization of new environments by the common ancestor of Ceratocephala and Myosurus. The seven and two genes under positive selection might be related to the adaptation to dry and aquatic habitats in Ceratocephala and Myosurus, respectively. Moreover, intensified aridity and frequent sea-level fluctuations, as well as global cooling, might have favored an increased rate of change in some genes at about 3.3 Ma, associated with adaptation to dry and aquatic environments, respectively. These findings suggest that changing environments might have influenced structural variations of plastomes and fixed new mutations arising on some plastid genes owing to adaptation to specific habitats.

Genomic data and ecological niche modeling reveal an unusually slow rate of molecular evolution in the Cretaceous Eupteleaceae.

Living fossils are evidence of long-term sustained ecological success. However, whether living fossils have little molecular changes remains poorly known, particularly in plants. Here, we have introduced a novel method that integrates phylogenomic, comparative genomic, and ecological niche modeling analyses to investigate the rate of molecular evolution of Eupteleaceae, a Cretaceous relict angiosperm family endemic to East Asia. We assembled a high-quality chromosome-level nuclear genome, and the chloroplast and mitochondrial genomes of a member of Eupteleaceae (Euptelea pleiosperma). Our results show that Eupteleaceae is most basal in Ranunculales, the earliest-diverging order in eudicots, and shares an ancient whole-genome duplication event with the other Ranunculales. We document that Eupteleaceae has the slowest rate of molecular changes in the observed angiosperms. The unusually low rate of molecular evolution of Eupteleaceae across all three independent inherited genomes and genes within each of the three genomes is in association with its conserved genome architecture, ancestral woody habit, and conserved niche requirements. Our findings reveal the evolution and adaptation of living fossil plants through large-scale environmental change and also provide new insights into early eudicot diversification.

Corrigendum: Organization, phylogenetic marker exploitation, and gene evolution in the plastome of Thalictrum (Ranunculaceae).

[This corrects the article DOI: 10.3389/fpls.2022.897843.].

The synergy of abiotic and biotic factors correlated with diversification of Fumarioideae (Papaveraceae) in the Cenozoic.

Rapid diversification of a group is often associated with exploiting an ecological opportunity and/or the evolution of a key innovation. However, how the interplay of such abiotic and biotic factors correlates with organismal diversification has been rarely documented in empirical studies, especially for organisms inhabiting drylands. Fumarioideae is the largest subfamily in Papaveraceae and is mainly distributed in temperate regions of the Northern Hemisphere. Here, we used one nuclear (ITS) and six plastid (rbcL, atpB, matK, rps16, trnL-F, and trnG) DNA sequences to investigate the spatio-temporal patterns of diversification and potential related factors of this subfamily. We first present the most comprehensive phylogenetic analysis of Fumarioideae to date. The results of our integrated molecular dating and biogeographic analyses indicate that the most recent common ancestor of Fumarioideae started to diversify in Asia during the Upper Cretaceous, and then dispersed multiple times out of Asia in the Cenozoic. In particular, we discover two independent dispersal events from Eurasia to East Africa in the late Miocene, suggesting that the Arabian Peninsula might be an important exchange corridor between Eurasia and East Africa in the late Miocene. Within the Fumarioideae, increased speciation rates were detected in two groups, Corydalis and Fumariinae. Corydalis first experienced a burst of diversification in its crown group at âˆ¼ 42 Ma, and further accelerated diversification from the mid-Miocene onwards. During these two periods, Corydalis had evolved diverse life history types, which could have facilitated the colonization of diverse habitats originating from extensive orogenesis in the Northern Hemisphere as well as Asian interior desertification. Fumariinae underwent a burst of diversification at âˆ¼ 15 Ma, which temporally coincides with the increasing aridification in central Eurasia, but is markedly posterior to the shifts in habitat (from moist to arid) and in life history (from perennial to annual) and to range expansion from Asia to Europe, suggesting that Fumariinae species may have been pre-adapted to invade European arid habitats by the acquisition of annual life history. Our study provides an empirical case that documents the importance of pre-adaptation on organismal diversification in drylands and highlights the significant roles of the synergy of abiotic and biotic factors in promoting plant diversification.

Biogeographic diversification of Actaea (Ranunculaceae): Insights into the historical assembly of deciduous broad-leaved forests in the Northern Hemisphere.

The deciduous broad-leaved forests (DBLFs) cover large temperate and subtropical high-altitude regions in the Northern Hemisphere. They are home to rich biodiversity, especially to numerous endemic and relict species. However, we know little about how this vegetation in the Northern Hemisphere has developed through time. Here, we used Actaea (Ranunculaceae), an herbaceous genus almost exclusively growing in the understory of the Northern Hemisphere DBLFs, to shed light on the historical assembly of this biome in the Northern Hemisphere. We present a complete species-level phylogenetic analysis of Actaea based on five plastid and nuclear loci. Using the phylogenetic framework, we estimated divergence times, ancestral ranges, and diversification rates. Phylogenetic analyses strongly support Actaea as monophyletic. Sections Podocarpae and Oligocarpae compose a clade, sister to all other Actaea. The sister relationship between sections Chloranthae and Souliea is strongly supported. Section Dichanthera is not monophyletic unless section Cimicifuga is included. Actaea originated in East Asia, likely the Qinghai-Tibet Plateau, in the late Paleocene (c. 57 Ma), and subsequently dispersed into North America in the middle Eocene (c. 43 Ma) via the Thulean bridge. Actaea reached Europe twice, Japan twice, and Taiwan once, and all these five colonization events occurred in the late Miocene-early Pliocene, a period when sea level dropped. Actaea began to diversify at c. 43 Ma. The section-level diversification took place at c. 27-37 Ma and the species-level diversification experienced accelerations twice, which occurred at c. 15 Ma and c. 5 Ma, respectively. Our findings suggest that the Northern Hemisphere DBLFs might have risen in the middle Eocene and further diversified in the late Eocene-Oligocene, middle Miocene and early Pliocene, in association with climatic deterioration during these four periods.

Plastome evolution and phylogenomics of Trichosporeae (Gesneriaceae) with its morphological characters appraisal.

Trichosporeae is the largest and most taxonomically difficult tribe of Gesneriaceae due to its diverse morphology. Previous studies have not clarified the phylogenetic relationships within this tribe on several DNA markers, including the generic relationships within subtribes. Recently, plastid phylogenomics have been successfully employed to resolve the phylogenetic relationships at different taxonomic levels. In this study, plastid phylogenomics were used to explore the relationships within Trichosporeae. Eleven plastomes of Hemiboea were newly reported. Comparative analyses, phylogeny and morphological character evolution within Trichosporeae were conducted on 79 species representing seven subtribes. The Hemiboea plastomes range from 152,742 bp to 153,695 bp in length. Within Trichosporeae, the sampled plastomes range from 152,196 bp to 156,614 bp and GC content from 37.2% to 37.8%. A total of 121-133 genes were annotated in each species, including 80-91 protein-coding genes, 34-37 tRNA genes, and 8 rRNA genes. The contraction and expansion of IR borders were not detected, and gene rearrangements and inversions did not occur. The 13 hypervariable regions were proposed as the potential molecular markers for species identification. A total of 24,299 SNPs and 3,378 indels were inferred, and most of the SNPs were functionally missense and silent variations. There were 1968 SSRs, 2055 tandem repeats and 2802 dispersed repeats. The RSCU and ENC values indicated that the codon usage pattern was conserved in Trichosporeae. Both the phylogenetic frameworks based on the whole plastome and 80 CDSs were basically concordant. The sister relationships between Loxocarpinae and Didymocarpinae were confirmed, and Oreocharis was a sister group of Hemiboea with high support. The morphological characters showed a complex evolutionary pattern of Trichosporeae. Our findings may contribute to future research on genetic diversity, morphological evolutionary patterns, and conservation of the tribe Trichosporeae.

The pan-plastome of tartary buckwheat (fagopyrum tataricum): key insights into genetic diversity and the history of lineage divergence.

BACKGROUND: Tartary buckwheat (Fagopyrum tataricum) is an important food and medicine crop plant, which has been cultivated for 4000 years. A nuclear genome has been generated for this species, while an intraspecific pan-plastome has yet to be produced. As such a detailed understanding of the maternal genealogy of Tartary buckwheat has not been thoroughly investigated. RESULTS: In this study, we de novo assembled 513 complete plastomes of Fagopyrum and compared with 8 complete plastomes of Fagopyrum downloaded from the NCBI database to construct a pan-plastome for F. tartaricum and resolve genomic variation. The complete plastomes of the 513 newly assembled Fagopyrum plastome sizes ranged from 159,253 bp to 159,576 bp with total GC contents ranged from 37.76 to 37.97%. These plastomes all maintained the typical quadripartite structure, consisting of a pair of inverted repeat regions (IRA and IRB) separated by a large single copy region (LSC) and a small single copy region (SSC). Although the structure and gene content of the Fagopyrum plastomes are conserved, numerous nucleotide variations were detected from which population structure could be resolved. The nucleotide variants were most abundant in the non-coding regions of the genome and of those the intergenic regions had the most. Mutational hotspots were primarily found in the LSC regions. The complete 521 Fagopyrum plastomes were divided into five genetic clusters, among which 509 Tartary buckwheat plastomes were divided into three genetic clusters (Ft-I/Ft-II/Ft-III). The genetic diversity in the Tartary buckwheat genetic clusters was the greatest in Ft-III, and the genetic distance between Ft-I and Ft-II was the largest. Based on the results of population structure and genetic diversity analysis, Ft-III was further subdivided into three subgroups Ft-IIIa, Ft-IIIb, and Ft-IIIc. Divergence time estimation indicated that the genera Fagopyrum and Rheum (rhubarb) shared a common ancestor about 48 million years ago (mya) and that intraspecies divergence in Tartary buckwheat began around 0.42 mya. CONCLUSIONS: The resolution of pan-plastome diversity in Tartary buckwheat provides an important resource for future projects such as marker-assisted breeding and germplasm preservation.

Master graph: an essential integrated assembly model for the plant mitogenome based on a graph-based framework.

Unlike the typical single circular structure of most animal mitochondrial genomes (mitogenome), the drastic structural variation of plant mitogenomes is a result of a mixture of molecules of various sizes and structures. Obtaining the full panoramic plant mitogenome is still considered a roadblock in evolutionary biology. In this study, we developed a graph-based sequence assembly toolkit (GSAT) to construct the pan-structural landscape of plant mitogenome with high-quality mitochondrial master graphs (MMGs) for model species including rice (Oryza sativa) and thale cress (Arabidopsis thaliana). The rice and thale cress MMGs have total lengths of 346 562 and 358 041 bp, including 9 and 6 contigs and 12 and 8 links, respectively, and could be further divided into 6 and 3 minimum master circles and 4 and 2 minimum secondary circles separately. The nuclear mitochondrial DNA segments (NUMTs) in thale cress strongly affected the frequency evaluation of the homologous structures in the mitogenome, while the effects of NUMTs in rice were relatively weak. The mitochondrial plastid DNA segments (MTPTs) in both species had no effects on the assessment of the MMGs. All potential recombinant structures were evaluated, and the findings revealed that all, except for nuclear-homologous structures, MMG structures are present at a much higher frequency than non-MMG structures are. Investigations of potential circular and linear molecules further supported multiple dominant structures in the mitogenomes and could be completely summarized in the MMG. Our study provided an efficient and accurate model for assembling and applying graph-based plant mitogenomes to assess their pan-structural variations.

A complete genus-level phylogeny reveals the Cretaceous biogeographic diversification of the poppy family.

Angiosperms, a trigger for the Cretaceous Terrestrial Revolution (KTR), underwent a rapid expansion and occupied all the environments during the Mid-Upper Cretaceous. Yet, Cretaceous biogeographic patterns and processes underlying the distribution of angiosperm diversity in the Northern Hemisphere are still poorly known. Here, we elucidated the biogeographic diversification of the angiosperm family Papaveraceae, an ancient Northern Hemisphere clade characterized by poor dispersal ability and high level of regional endemism. Based on both plastome and multi-locus datasets, we reconstructed a robust time-calibrated phylogeny that includes all currently recognized 45 genera of this family. Within the time-calibrated phylogenetic framework, we conducted 72 biogeographic analyses by testing the sensitivity of uncertainties of area delimitation, maxarea constraints, and the parameters of the model, i.e., j (describing jump-dispersal events) and w (modifying dispersal multiplier matrices), to ancestral range estimations. We also inferred ancestral habitat and ecological niches. Phylogenetic analyses strongly support Papaveraceae as monophyletic. Pteridophylloideae is strongly supported as sister to Hypecoideae-Fumarioideae. Our results indicate that the j parameter and number of predefined areas strongly affect ancestral range estimates, generating questionable ancestral ranges, whereas maxarea constraint and w parameter have no effect and improve model fit. After accounting for these uncertainties, our results indicate that Papaveraceae differentiated in Asian wet forests during the Lower Cretaceous and subsequently occupied the Asian and western North American arid and open areas. Three dispersals from Asia to western North America via the Bering land bridge occurred in the Mid-Upper Cretaceous, largely in agreement with the KTR. Habitat shift and ecological niche divergence resulted in the subsequent disjunctions between Asia and western North America. These findings suggest that the interplay of range expansion and niche divergence-driven vicariance might have shaped Cretaceous biogeographic patterns of angiosperms with Papaveraceae-like ecological requirements and dispersal abilities in the Northern Hemisphere, hence contributing to the knowledge on the geographic expansion of angiosperms during the KTR.

Karyotypes and Physical Mapping of Ribosomal DNA with Oligo-Probes in Eranthis sect. Eranthis (Ranunculaceae).

A comparative karyotype analysis of four species of yellow-flowered Eranthis sect. Eranthis, i.e., E. bulgarica, E. cilicica, E. hyemalis, and E. longistipitata from different areas, has been carried out for the first time. All the studied specimens had somatic chromosome number 2n = 16 with basic chromosome number x = 8. Karyotypes of the investigated plants included five pairs of metacentric chromosomes and three pairs of submetacentric/subtelocentric chromosomes. The chromosome sets of the investigated species differ mainly in the ratio of submetacentric/subtelocentric chromosomes, their relative lengths, and arm ratios. A new oligonucleotide probe was developed and tested to detect 45S rDNA clusters. Using this probe and an oligonucleotide probe to 5S rDNA, 45S and 5S rDNA clusters were localized for the first time on chromosomes of E. cilicica, E. hyemalis, and E. longistipitata. Major 45S rDNA clusters were identified on satellite chromosomes in all the species; in E. cilicica, minor clusters were also identified in the terminal regions of one metacentric chromosome pair. The number and distribution of 5S rDNA clusters is more specific. In E. cilicica, two major clusters were identified in the pericentromeric region of a pair of metacentric chromosomes. Two major clusters in the pericentromeric region of a pair of submetacentric chromosomes and two major clusters in the interstitial region of a pair of metacentric chromosomes were observed in E. longistipitata. E. hyemalis has many clusters of different sizes, localized mainly in the pericentromeric regions. Summarizing new data on the karyotype structure of E. sect. Eranthis and previously obtained data on E. sect. Shibateranthis allowed conclusions to be formed about the clear interspecific karyological differences of the genus Eranthis.

Organization, Phylogenetic Marker Exploitation, and Gene Evolution in the Plastome of Thalictrum (Ranunculaceae).

Thalictrum is a phylogenetically and economically important genus in the family Ranunculaceae, but is also regarded as one of the most challengingly difficult in plants for resolving the taxonomical and phylogenetical relationships of constituent taxa within this genus. Here, we sequenced the complete plastid genomes of two Thalictrum species using Illumina sequencing technology via de novo assembly. The two Thalictrum plastomes exhibited circular and typical quadripartite structure that was rather conserved in overall structure and the synteny of gene order. By updating the previously reported plastome annotation of other nine Thalictrum species, we found that the expansion or contraction of the inverted repeat region affect the boundary of the single-copy regions in Thalictrum plastome. We identified eight highly variable noncoding regions-infA-rps8, ccsA-ndhD, trnSUGA-psbZ, trnHGUG-psbA, rpl16-rps3, ndhG-ndhI, ndhD-psaC, and ndhJ-ndhK-that can be further used for molecular identification, phylogenetic, and phylogeographic in different species. Selective pressure and codon usage bias of all the plastid coding genes were also analyzed for the 11 species. Phylogenetic relationships showed Thalictrum is monophyly and divided into two major clades based on 11 Thalictrum plastomes. The availability of these plastomes offers valuable genetic information for accurate identification of species and taxonomy, phylogenetic resolution, and evolutionary studies of Thalictrum, and should assist with exploration and utilization of Thalictrum plants.

Integrated multi-omic data and analyses reveal the pathways underlying key ornamental traits in carnation flowers.

Carnation (Dianthus caryophyllus) is one of the most popular ornamental flowers in the world. Although numerous studies on carnations exist, the underlying mechanisms of flower color, fragrance, and the formation of double flowers remain unknown. Here, we employed an integrated multi-omics approach to elucidate the genetic and biochemical pathways underlying the most important ornamental features of carnation flowers. First, we assembled a high-quality chromosome-scale genome (636 Mb with contig N50 as 14.67 Mb) of D. caryophyllus, the 'Scarlet Queen'. Next, a series of metabolomic datasets was generated with a variety of instrumentation types from different parts of the flower at multiple stages of development to assess spatial and temporal differences in the accumulation of pigment and volatile compounds. Finally, transcriptomic data were generated to link genomic, biochemical, and morphological patterns to propose a set of pathways by which ornamental traits such as petal coloration, double flowers, and fragrance production are formed. Among them, the transcription factors bHLHs, MYBs, and a WRKY44 homolog are proposed to be important in controlling petal color patterning and genes such as coniferyl alcohol acetyltransferase and eugenol synthase are involved in the synthesis of eugenol. The integrated dataset of genomics, transcriptomics, and metabolomics presented herein provides an important foundation for understanding the underlying pathways of flower development and coloration, which in turn can be used for selective breeding and gene editing for the development of novel carnation cultivars.

The History and Diversity of Rice Domestication as Resolved From 1464 Complete Plastid Genomes.

The plastid is an essential organelle in autotrophic plant cells, descending from free-living cyanobacteria and acquired by early eukaryotic cells through endosymbiosis roughly one billion years ago. It contained a streamlined genome (plastome) that is uniparentally inherited and non-recombinant, which makes it an ideal tool for resolving the origin and diversity of plant species and populations. In the present study, a large dataset was amassed by de novo assembling plastomes from 295 common wild rice (Oryza rufipogon Griff.) and 1135 Asian cultivated rice (Oryza sativa L.) accessions, supplemented with 34 plastomes from other Oryza species. From this dataset, the phylogenetic relationships and biogeographic history of O. rufipogon and O. sativa were reconstructed. Our results revealed two major maternal lineages across the two species, which further diverged into nine well supported genetic clusters. Among them, the Or-wj-I/II/III and Or-wi-I/II genetic clusters were shared with cultivated (percentage for each cluster ranging 54.9%∼99.3%) and wild rice accessions. Molecular dating, phylogeographic analyses and reconstruction of population historical dynamics indicated an earlier origin of the Or-wj-I/II genetic clusters from East Asian with at least two population expansions, and later origins of other genetic clusters from multiple regions with one or more population expansions. These results supported a single origin of japonica rice (mainly in Or-wj-I/II) and multiple origins of indica rice (in all five clusters) for the history of rice domestication. The massive plastomic data set presented here provides an important resource for understanding the history and evolution of rice domestication as well as a genomic resources for use in future breeding and conservation efforts.

Biogeographic diversification of Eranthis (Ranunculaceae) reflects the geological history of the three great Asian plateaus.

The evolutionary history of organisms with poor dispersal abilities usually parallels geological events. Collisions of the Indian and Arabian plates with Eurasia greatly changed Asian topography and affected regional and global climates as well as biotic evolution. However, the geological evolution of Asia related to these two collisions remains debated. Here, we used Eranthis, an angiosperm genus with poor seed dispersal ability and a discontinuous distribution across Eurasia, to shed light on the orogenesis of the Qinghai-Tibetan, Iranian and Mongolian Plateaus. Our phylogenetic analyses show that Eranthis comprises four major geographical clades: east Qinghai-Tibetan Plateau clade (I-1), North Asian clade (I-2), west Qinghai-Tibetan Plateau clade (II-1) and Mediterranean clade (II-2). Our molecular dating and biogeographic analyses indicate that within Eranthis, four vicariance events correlate well with the two early uplifts of the Qinghai-Tibetan Plateau during the Late Eocene and the Oligocene-Miocene boundary and the two uplifts of the Iranian Plateau during the Middle and Late Miocene. The origin and divergence of the Mongolian Plateau taxa are related to the two uplifts of the Mongolian Plateau during the Middle and Late Miocene. Additionally, our results are in agreement with the hypothesis that the central part of Tibet only reached an altitude of less than 2.3 km at approximately 40 Ma. This study highlights that organismal evolution could be related to the formation of the three great Asian plateaus, hence contributing to the knowledge on the timing of the key tectonic events in Asia.

Biogeographic diversification of Mahonia (Berberidaceae): Implications for the origin and evolution of East Asian subtropical evergreen broadleaved forests.

The subtropical evergreen broadleaved forests (EBLFs) inhabit large areas of East Asia and harbor rich biodiversity and high endemism. However, the origin and evolution of biodiversity of East Asian subtropical EBLFs remain poorly understood. Here, we used Mahonia (Berberidaceae), an eastern Asian-western North American disjunct evergreen genus, to obtain new insights into the historical assembly of this biome. We present the most comprehensive phylogenetic analysis of Mahonia do date based on six nuclear and plastid loci. Using the phylogenetic framework, we estimated divergence times, reconstructed ancestral ranges, inferred evolutionary shift of habitats, and estimated diversification rates. Mahonia and each of its two groups (Orientales and Occidentales) are strongly supported as monophyletic. Mahonia originated in western North America during the late Eocene (c. 40.41 Ma) and subsequently dispersed into East Asia prior to the early Oligocene (c. 32.65 Ma). The North Atlantic Land Bridge might have played an important role in population exchanges of Mahonia between East Asia and western North America. The western North American Occidentales began to diversify in summer-dry climates and open landscapes in the early Miocene, whereas the eastern Asian Orientales began to diversify in subtropical EBLFs in the early Miocene and furthermore had a rapid lineage accumulation since the late Miocene. The net diversification rate of Mahonia in eastern Asia appeared to be higher than that in western North America, which is ascribed to lower extinction rates and ecological opportunity. Our findings suggest that western North America is a source of biodiversity of East Asian subtropical EBLFs. This biome in eastern Asia began to rise in the early Miocene and further diversified in the late Miocene, driven by the intensifying East Asian summer monsoon during these two periods.

An integrative taxonomic approach reveals a new species of Eranthis (Ranunculaceae) in North Asia.

A new endemic species, Eranthis tanhoensis sp. nov., is described from the Republic of Buryatia and Irkutsk Province, Russia. It belongs to Eranthis section Shibateranthis and is morphologically similar to E. sibirica and E. stellata. An integrative taxonomic approach, based on cytogenetical, molecular and biochemical analyses, along with morphological data, was used to delimit this new species.

A dated phylogeny of Lardizabalaceae reveals an unusual long-distance dispersal across the Pacific Ocean and the rapid rise of East Asian subtropical evergreen broadleaved forests in the late Miocene.

Temperate South American-Asian disjunct distributions are the most unusual in organisms, and challenging to explain. Here, we address the origin of this unusual disjunction in Lardizabalaceae using explicit models and molecular data. The family (c.40 species distributed in ten genera) also provides an opportunity to explore the historical assembly of East Asian subtropical evergreen broadleaved forests, a typical and luxuriant vegetation in East Asia. DNA sequences of five plastid loci of 42 accessions representing 23 species of Lardizabalaceae (c. 57.5% of estimated species diversity), and 19 species from the six other families of Ranunculales, were used to perform phylogenetic analyses. By dating the branching events and reconstructing ancestral ranges, we infer that extant Lardizabalaceae dated to the Upper Cretaceous of East Asia and that the temperate South American lineage might have split from its East Asian sister group at c. 24.4 Ma. A trans-Pacific dispersal possibly by birds from East Asia to South America is plausible to explain the establishment of the temperate South American-East Asian disjunction in Lardizabalaceae. Diversification rate analyses indicate that net diversification rates of Lardizabalaceae experienced a significant increase around c. 7.5 Ma. Our findings suggest that the rapid rise of East Asian subtropical evergreen broadleaved forests occurred in the late Miocene, associated with the uplift of the Tibetan Plateau and the intensified East Asian monsoon, as well as the higher winter temperature and atmospheric CO2 levels.

A multi-locus phylogeny for the Neotropical Anomospermeae (Menispermaceae): Implications for taxonomy and biogeography.

Neotropical rainforests cover about half of the world's tropical rainforests and house most of the biodiversity available on Earth. Australasia has been suggested as a potential source for Neotropical diversity. However, it remains unclear whether megathermal lineages could indeed have migrated to South America though Antarctica. The Neotropical Anomospermeae (Menispermaceae) consists of large, canopy lianas and is entirely restricted to tropical lowland rainforests. The sister relationship identified between this group and its Australasian ally represents an excellent model to test hypotheses regarding past connections between those landmasses. In this study, we used six chloroplast and two nuclear DNA markers to reconstruct phylogenetic relationships within the Neotropical Anomospermeae (Menispermaceae). The phylogeny of this group was then used as basis to reconstruct its biogeographical history. The phylogenetic framework reconstructed here strongly supports the monophyly of the Neotropical Anomospermeae and recovers the species of Anomospermum in three different clades: (i) Anomospermum sect. Anomospermum plus Orthomene; (ii) Anomospermum grandifolium and A. solimoesanum (Anomospermum sect. Elissarrhena); and (iii) Anomospermum bolivianum (Anomospermum sect. Elissarrhena). Each of these clades is recognized as a different genus and the necessary taxonomic changes are proposed. Furthermore, the Neotropical Anomospermeae seems to have split from its Australasian sister-group at c. 62 Ma. Ancestral area reconstructions support an Australasian origin for the Neotropical Anomospermeae, providing additional support for the hypothesis that Australasia is a source of Neotropical diversity, with megathermal lineages having dispersed via Antarctica. The Neotropical Anomospermeae differentiated in the late Eocene and subsequently diversified rapidly into seven lineages, suggesting that Neotropical lowland rainforests resembling modern rainforests physiognomically and structurally might not have developed until the late Eocene. The Neotropical Anomospermeae exemplifies the contributions of Australasian migration to Neotropical diversity.

Trolliusaustrosibiricus (Ranunculaceae), a new species from South Siberia.

Trolliusaustrosibiricus Erst & Luferov, sp. nov., a new species from Russian South Siberia is described and illustrated. This new species is endemic to Western and Central Siberia. Morphologically, it is close to the East Asian species T.chinensis and T.macropetalus. However, it differs from the aforementioned species due to the morphology of the rhizomes, aerial shoots, sepals and petals. This species is also distinguished from T.asiaticus, which is widespread in Russia (Western and Eastern Siberia), Mongolia, China, north-eastern Kazakhstan and in the northeast of the European part of Russia, in having a smaller number of sepals, longer persistent styles and petals longer than sepals. In addition, an identification key for all Russian species is given and all species have been discussed.

Biogeography of Coptis Salisb. (Ranunculales, Ranunculaceae, Coptidoideae), an Eastern Asian and North American genus.

BACKGROUND: Numerous studies have favored dispersal (colonization) over vicariance (past fragmentation) events to explain eastern Asian-North American distribution patterns. In plants, however the disjunction between eastern Asia and western North America has been rarely examined using the integration of phylogenetic, molecular dating, and biogeographical methods. Meanwhile, the biogeographic patterns within eastern Asia remain poorly understood. The goldthread genus Coptis Salisb. includes 15 species disjunctly distributed in North America, Japan, mainland China, and Taiwan. We present a dated phylogeny for Coptis under the optimal clock model and infer its historical biogeography by comparing different biogeographic models. RESULTS: The split of Coptis and Xanthorhiza Marshall occurred in the middle Miocene (ca. 15.47 Ma). Coptis started their diversification in the early late Miocene (ca. 9.55 Ma). A late Miocene vicariance event resulted in the eastern Asian and western North American disjunction in the genus. Within eastern Asia, dispersals from mainland Asia to Japan and from Japan to Taiwan occurred at ca. 4.85 Ma and at ca. 1.34 Ma, respectively. CONCLUSIONS: Our analyses provide evidence that both vicariance and dispersal events have played important roles in shaping the current distribution and endemism of Coptis, likely resulting from eustatic sea-level changes, mountain formation processes and an increasing drier and cooler climate from the middle Miocene onwards.