Integrative biogeography: Validating hypotheses of species distribution

DEAR EDITOR,Biogeography is a scientific field dedicated to the investigation of the origins and distribution patterns of organisms,as well as predicting future alterations in their geographical distributions(Cox&Moore,2005).However,the majority of conclusions drawn within the field of biogeography are hypothetical.Rigorous testing of these biogeographic hypotheses remains a considerable challenge.This paper presents the concept of“integrative biogeography”,which emphasizes the experimental testing of biogeographic hypotheses through studies on geological history,as well as biotic and abiotic factors(Figure 1).

Progress in systematics and biogeography of Orchidaceae

Orchidaceae are one of the largest families of angiosperms in terms of species richness.In the last decade,numerous studies have delved into reconstructing the phylogenetic framework of Orchidaceae,leveraging data from plastid,mitochondrial and nuclear sources.These studies have provided new insights into the systematics,diversification and biogeography of Orchidaceae,establishing a robust foundation for future research.Nevertheless,pronounced controversies persist regarding the precise placement of certain lineages within these phylogenetic frameworks.To address these discrepancies and deepen our understanding of the phylogenetic structure of Orchidaceae,we provide a comprehensive overview and analysis of phylogenetic studies focusing on contentious groups within Orchidaceae since 2015,delving into discussions on the underlying reasons for observed topological conflicts.We also provide a novel phylogenetic framework at the subtribal level.Furthermore,we examine the tempo and mode underlying orchid species diversity from the perspective of historical biogeography,highlighting factors contributing to extensive speciation.Ultimately,we delineate avenues for future research aimed at enhancing our understanding of Orchidaceae phylogeny and diversity.

Island biogeography theory and the habitat heterogeneity jointly explain global patterns of Rhododendron diversity

Mountain biodiversity is of great importance to biogeography and ecology.However,it is unclear what ecological and evolutionary processes best explain the generation and maintenance of its high levels of species diversity.In this study,we determined which of six common hypotheses(e.g.,climate hypotheses,habitat heterogeneity hypothesis and island biogeography theory)best explain global patterns of species diversity in Rhododendron.We found that Rhododendron diversity patterns were most strongly explained by proxies of island biogeography theory(i.e.,mountain area)and habitat heterogeneity(i.e.,elevation range).When we examined other relationships important to island biogeography theory,we found that the planimetric area and the volume of mountains were positively correlated with the Rhododendron diversity,whereas the‘mountains-to-mainland’distance was negatively correlated with Rhododendron diversity and shared species.Our findings demonstrate that Rhododendron diversity can be explained by island biogeography theory and habitat heterogeneity,and mountains can be regarded as islands which supported island biogeography theory.

Why is the beautyberry so colourful? Evolution,biogeography,and diversification of fruit colours in Callicarpa(Lamiaceae)

Fruit colour is essential to seed dispersal,speciation,and biological diversity in global ecosystems.The relationship between fruit-colour variation and species diversification has long been of interest in evolutionary biology,but remains poorly understood at the genus level.Here,we used Callicarpa,a typical representative of pantropical angiosperm,to analyse whether fruit colours are correlated with biogeographic distribution,dispersal events,and diversification rate.We estimated a time-calibrated phylogeny for Callicarpa and reconstructed ancestral fruit colour.Utilizing phylogenetic methods,we estimated the major dispersal events across the phylogenetic tree and the most likely fruit colours related to each dispersal event,and tested whether the dispersal frequencies and distances of the four fruit colours between major biogeographical areas were equal.We then tested whether fruit colours are correlated with latitude,elevation,and diversification rate.Biogeographical reconstructions showed that Callicarpa originated in the East Asia and Southeast Asia during the Eocene(-35.53 Ma) and diverse species diverged mainly in the Miocene and lasted into the Pleistocene.Large-scale dispersal events were significantly associated with violet-fruited lineages.Furthermore,different fruit colours were markedly correlated with different latitudes and elevations(e.g.,violet fruits were correlated with higher latitudes and elevations;red fruits and black fruits with lower latitudes;white fruits with higher elevations).Notably,violet fruits were statistically associated with highest diversification rates,driving fruit colour variation among different regions globally.Our results contribute to further understanding why fruit colour is so variable at the genus level of angiosperms in different areas around the world.

Phytoplanktonic biogeography in the subtropical coastal waters,East China Sea along intensive anthropogenic stresses: roles of environmental versus spatial factors

Understanding the relative roles of local environmental effects and spatial effects on phytoplankton community is of essential importance to study the biogeography of them at regional scale. However, the determinants that driving the biogeography of phytoplankton communities in the coastal area of northern Zhejiang still remained unclear. We surveyed phytoplankton community compositions in water columns associated with environmental and spatial influences across five subzones that geographically covering this region over four seasons. Diatoms and dinoflagellates were recorded as the main dominant groups and Coscinodiscus oculs-iridis, Coscinodiscus jonesianus, and Skeletonema costatum, were identified as the major abundant species existing in all seasons.Spatially structured environmental conditions, rather than pure spatial or environmental factors, substantially shaped the biogeography of phytoplankton community, with the former mainly comprised of water temperature,dissolved oxygen, phosphate, pH, and salinity, and the latter referring to a non-negligible factor. This study was the first integrated research that combining environmental filtering with spatial factors in structuring phytoplankton communities at a complete tempo-spatial scale. Our results may facilitate to the further study of harmful algal blooms early-warning in this region.

Inventory, Systematic and Biogeography of Brachyuran Crabs (Crustacea: Decapoda: Brachyura) on the Tunisian Coast

Several prospects on the northern, central and southern Tunisian coasts were carried out for the sake of a better interpretation of Brachyuran species distribution. Animals were either, captured by hand, caught with a fine mesh net or brought back by fishermen in nets or dredges. A total of 21 species belonging to twelve families and inhabiting different substrates were collected and divided into littoral species and species of depth. Five species were reported for the first time, in Tunisia. The littoral species are Carcinus aestuarii, Liocarcinus corrugatus, Liocarcinus vernalis, Pachygrapsus marmoratus, Pachygrapsus maurus, Brachynotus sexdentatus, Eriphia verrucosa, Maja squinado, Maja crispata, Acanthonyx lunulatus and Pisa tetraodon. The species of depths are Portunus hastatus, Euchirograpsus liguricus, Xantho granulicarpus, Ilia nucleus, Inachus dorsettensis, Lissa chiragra, Pisa corallina, Pisa armata, Calappa granulata and Dromia personata. All these species are reported in the Mediterranean. Some are reported for the first time in Tunisia: P. maurus, A. lunulatus, P. hastatus, E. liguricus, L. chiragra and P. corallina. In order to know the frequency of each species, the presence index was calculated. Carcinus aestuarii present in 91% of prospected stations is the most frequent and wide-distributed brachyuran species along Tunisian coasts.

Reconstructing ancestral ranges in historical biogeography:properties and prospects

Recent years have witnessed a proliferation of quantitative methods for biogeographic inference. In particular, novel parametric approaches represent exciting new opportunities for the study of range evolution. Here, we review a selection of current methods for biogeographic analysis and discuss their respective properties. These methods include generalized parsimony approaches, weighted ancestral area analysis, dispersal-vicariance analysis, the dispersal--extinction--cladogenesis model and other maximum likelihood approaches, and Bayesian stochastic mapping of ancestral ranges, including a novel approach to inferring range evolution in the context of island biogeography. Some of these methods were developed specifically for problems of ancestral range reconstruction, whereas others were designed for more general problems of character state reconstruction and subsequently applied to the study of ancestral ranges. Methods for reconstructing ancestral history on a phylogenetic tree differ not only in the types of ancestral range states that are allowed, but also in the various historical events that may change the ancestral ranges. We explore how the form of allowed ancestral ranges and allowed transitions can both affect the outcome of ancestral range estimation. Finally, we mention some promising avenues for future work in the development of model-based approaches to biogeographic analysis.

Biogeography of the leafhopper subfamily Stegelytrinae(Hemiptera:Cicadellidae),based on a cluster analysis of geographical distribution in areas of endemism combined with phylogeny of the subfamily

Biogeography of the leaflaopper subfamily Stegelytrinae Baker is studied based on an analysis of geographical distribution of this subfamily worldwide using a cluster analysis of the zoological distribution of areas of endemism as well as the phylogeny of representatives of this subfamily. Results show that the Stegelytrinae mainly occur in the Oriental Region and in the Mediterranean area of the Palaearctic Region, and this extends to the east side of both Wallaee＇s and Weber＇s lines. Eleven areas of endemism of this subfamily are recognized. The proportions of endemic taxa in different areas of endemism are generally very high in comparison with other leaflaopper groups, but distinct differences could be found among the different areas of endemism of Stegelytrinae. This subfamily is most intensively diversified in the Indochina Peninsula （INCN）. This is the stegelytrine distribution center, having the highest biodiversity at both genetic and species levels. The dendrogram of endemic areas of Stegelytrinae constructed using cluster analysis of the zoological distribution of Stegelytrinae at generic level shows the endemic areas of Stegelytrinae can be divided into 4 large groups. Relationships among different endemic areas of Stegelytrinae correspond largely to the geologic history of related areas, which indicates that the evolution and vicariance of this subfamily have been closely related to the history of continental drift and climate changes. It is deduced that the presumed monophyletic Stegelytrinae originated in the Oriental Region after North America had separated from Eurasia; this is the case in the monophyletic genera group which is supported by the lateral frontal sutures extending dorsally well beyond the corresponding ocellus. In addition, two expanding traces of the Stegelytrinae are presumed, which remain plausible explanations for the dispersal of Stegelytrinae： （1） New Guinea （and probably （＋ Australia）） - Kalimantan - Sumatra - Malay Peninsula - Indochina Peninsula - Central and Southern China - （Southwestern China ＋ Nepal ＋ Northeastern India） - （Northwestern India ＋ Eastern Afghanistan）; and （2） Indochina Peninsula- Central and Southern China- （Western Asia ＋ Mediterranean Sea coastal area）.

Molecular diversity and biogeography of benthic ciliates in the Bohai Sea and Yellow Sea

This study explored the molecular diversity and biogeography of benthic ciliates in Chinese marginal seas, the Bohai Sea(BHS), North Yellow Sea(NYS) and South Yellow Sea(SYS). From a previous 18S rRNA gene pyrosequencing dataset of the benthic microeukaryotes, we retrieved the sequences affiliated with phylum Ciliophora and analyzed alpha and beta diversities of ciliate communities. We found that BHS had the highest ciliate operational taxonomic unit(OTU) richness than NYS and SYS, whereas the richness was not significantly different between summer and winter. Among all the measured environmental variables, water depth showed consistently the strongest correlations with alpha diversities. Overall, the class Spirotrichea(mostly Choreotrichia and unassigned lineages within the class) dominated the communities in terms of both relative proportion of sequences(77.0%) and OTU richness(66.5%). OTU-level ciliate community structure was significant different among the three basins, but not between the seasons. Structurally, significant differences in relative proportion among the basins were detected for the class Litostomatea, but not for other classes. Partial Mantel tests demonstrated that water depth difference was more important than geographic and environment distances in shaping the community structure of benthic ciliates in the studied area. About 60% OTUs were not assigned at a class or order level and at least 45% OTUs shared a sequence similarity no more than 97% with the described species, indicating a great potential for ciliate species discovery in the offshore sediments. Compared with previous morphology-based surveys, the spatial pattern of ciliate diversity(decreasing from NYS to SYS) is also identified in the present study. Nevertheless, structurally, the dominant class appeared to be Spirotrichea in the sequencing dataset, which differs from previous morphology-based results(dominance of classes Prostomatea and Karyorelictea in biomass). The potential causes for the discrepancies between molecular and morphological findings are also discussed.

A New Material of Lindera (Lauraceae) of the Late Pliocene from Tengchong, Yunnan and the Genus' Biogeography Significance

Lindera is a large genus of graceful, pleasantly scented and common native trees and shrubs of southern China and neighboring regions of SE Asia. There is a well-documented Cenozoic fossil record not only in these regions but also from elsewhere. A new fossil leaf record has been found in diatomite beds from the Upper Pliocene Mangbang Formation of Tuantian, Tengchong County, Yunnan. The leaves are identified and assigned to Lindera acuminatissima K. Q. Dao et B. N. Sun sp. nov., by comparing their leaf architecture and epidermal characteristics with those of 51 extant Lauraceae species and with 15 known fossil Lindera taxa. The specimens have well-preserved cuticles, with typical leaf architecture and epidermal characteristics of the Lanraceae, including entire leaf margin, intramarginal veins, basal ternate acrodromous primary veins, one-cell trichome base, paracytic stomatal apparatus, sunken guard cells, subsidiary hardly staining cells and presence of oil cells. These characteristics are consistent with Lindera sect. Daphnidium but are different from reported fossil and extant species of Lindera. The cuticles of Lindera are fragile and delicate with only three Lindera fossils reported based on this tissue. In terms of paleobiogeography, the fossil record indicates that Lindera is distributed in high- to mid-latitude regions of the Late Cretaceous to Paleocene northern hemisphere. Coincidentally, the records of Lindera located on both sides of the Bering Land Bridge possibly support the hypothesis that ancient plants extended via transcontinental exchanges through the Bering Corridor. In the Eocene, ancient Lindera spread to Europe through the Northern Degeer Route and the Southern Thulian Route. At the same time, ancient Lindera spread into Central Asia. Climatic changes and tectonization since the Neogene prevented the propagation of Lindera throughout Asia, North America and Europe, and hence the distribution areas have just regressed to the low-latitude regions in Asia and North America. From the Paleogene to the Neogene, Lindera has changed its distribution by surviving extreme climate changes. Quaternary glaciations ultimately led to Lindera becoming extinct in Europe. The new record from Tengchong, Yunnan, with its lower latitude located in tropical and subtropical regions, indicates that Lindera has lived in those regions since the late Pliocene.

Phylogenetic relationship,biogeography,and conservation genetics of endangered Fraxinus chiisanensis(Oleaceae),endemic to South Korea

Endemic plants are important for understanding phylogenetic relationships,biogeographical history,and genetic variation because of their restricted distribution and their role in conserving biodiversity.Here,we investigated the phylogenetic relationships of the Korean endemic Fraxinus chiisanensis by reconstructing the molecular phylogeny of Fraxinus based on two nuclear DNA(nrITS and phantastica)and two chloroplast DNA(psbA-trnH and rp132-trnL)regions.Within our fossil-calibrated phylogenetic framework,we also inferred the biogeographical history of F.chiisanensis.To provide a scientific basis for the conservation of F.chiisanensis,we determined the levels of genetic diversity and genetic differentiation in this species.Combining information from nuclear and chloroplast DNA sequence data,our molecular phylogenetic analyses identified F.chiisanensis as a genetically distinct unit from its sister group,Fraxinus platypoda from Japan.Our molecular dating analyses using nuclear and chloroplast DNA data sets show F.chiisanensis diverged from its sister F.platypoda in the Early or Middle Miocene and differentiated in the Late Miocene on the Korean Peninsula.Our results suggest that the divergence of F.chiisanensis was associated with the submergence of the East China Sea land bridge and enhanced monsoons in East Asia.When compared to F.platypoda,F.chiisanensis exhibits low genetic diversity within populations and high genetic differentiation among populations.These results help us to understand the evolutionary history of F.chiisanensis and to develop a conservation strategy for this species.

Plastid phylogenomics and biogeography of the medicinal plant lineage Hyoscyameae(Solanaceae)

The cosmopolitan family Solanaceae,which originated and first diversified in South America,is economically important.The tribe Hyoscyameae is one of the three clades in Solanaceae that occurs outside of the New World;Hyoscyameae genera are distributed mainly in Europe and Asia,and have centers of species diversity in the Qinghai-Tibet Plateau and adjacent regions.Although many phylogenetic studies have focused on Solanaceae,the phylogenetic relationships within the tribe Hyoscyameae and its biogeographic history remain obscure.In this study,we reconstructed the phylogeny of Hyoscyameae based on whole chloroplast genome data,and estimated lineage divergence times according to the newly reported fruit fossil from the Eocene Patagonia,Physalis infinemundi,the earliest known fossil of Solanaceae.We reconstructed a robust phylogeny of Hyoscyameae that reveals the berry fruit-type Atropa is sister to the six capsule-bearing genera(Hyoscyameae sensu stricto),Atropanthe is sister to the clade(Scopolia,Physochlaina,Przewalskia),and together they are sister to the robustly supported AnisoduseHyoscyamus clade.The stem age of Hyoscyameae was inferred to be in the Eocene(47.11 Ma,95%HPD:36.75e57.86 Ma),and the crown ages of Hyoscyameae sensu stricto were estimated as the early Miocene(22.52 Ma,95%HPD:15.19e30.53 Ma),which shows a close correlation with the rapid uplift of the Qinghai-Tibet Plateau at the Paleogene/Neogene boundary.Our results provide insights into the phylogenetic relationships and the history of the biogeographic diversification of the tribe Hyoscyameae,as well as plant diversification on the Qinghai-Tibet Plateau.

Molecular phylogeny,biogeography and character evolution of the montane genus Incarvillea Juss.(Bignoniaceae)

The complex orogeny of the Himalaya and the Qinghai-Tibet Plateau(QTP)fosters habitat fragmentation that drives morphological differentiation of mountain plant species.Consequently,determining phylogenetic relationships between plant subgenera using morphological characters is unreliable.Therefore,we used both molecular phylogeny and historical biogeographic analysis to infer the ancestral states of several vegetative and reproductive characters of the montane genus Incarvillea.We determined the taxonomic position of the genus Incarvillea within its family and inferred the biogeographical origin of taxa through Bayesian inference(BI),maximum likelihood(ML)and maximum parsimony(MP)analyses using three molecular data sets(trnL-trnF sequences,nr ITS sequences,and a data set of combined sequences)derived from 81%of the total species of the genus Incarvillea.Within the genus-level phylogenetic framework,we examined the character evolution of 10 key morphological characters,and inferred the ancestral area and biogeographical history of the genus.Our analyses revealed that the genus Incarvillea is monophyletic and originated in Central Asia during mid-Oligocene ca.29.42 Ma.The earliest diverging lineages were subsequently split into theWestern Himalaya and Sino-Himalaya during the early Miocene ca.21.12 Ma.These lineages resulted in five re-circumscribed subgenera(Amphicome,Olgaea,Niedzwedzkia,Incarvillea,and Pteroscleris).Moreover,character mapping revealed the ancestral character states of the genus Incarvillea(e.g.,suffruticose habit,cylindrical capsule shape,subligneous capsule texture,absence of capsule wing,and loculicidal capsule dehiscence)that are retained at the earliest diverging ancestral nodes across the genus.Our phylogenetic tree of the genus Incarvillea differs from previously proposed phylogenies,thereby recommending the placement of the subgenus Niedzwedzkia close to the subgenus Incarvillea and maintaining two main divergent lineages.

Phylogenetic analysis of combined mitochondrial genome and 32 nuclear genes provides key insights into molecular systematics and historical biogeography of Asian warty newts of the genus Paramesotriton(Caudata: Salamandridae)

The Paramesotriton Chang, 1935 genus of Asian warty newts is the second most diverse genus in the family Salamandridae, currently containing 14recognized species from northern Vietnam to southwest-central and southern China. Although species of this genus have been included in previous phylogenetic studies, the origin and interspecific relationships of the genus are still not fully resolved,especially at key nodes in the phylogeny. In this study, we sequenced mitochondrial genomes and 32nuclear genes from 27 samples belonging to 14species to reconstruct the interspecific phylogenetic relationships within Paramesotriton and explore its historical biogeography in southern China. Both Bayesianinferenceandmaximum-likelihood analyses highly supported the monophyly of Paramesotriton and its two recognized species groups(P. caudopunctatus and P. chinensis groups)and further identified five hypothetical phylogenetic cryptic species. Biogeographic analyses indicated that Paramesotriton originated in southwestern China(Yunnan-Guizhou Plateau/South China) during the late Oligocene. The time of origin of Paramesotriton corresponded to the second uplift of the Himalayan/Qinghai-Xizang(Tibetan) Plateau(QTP), rapid lateral extrusion of Indochina, and formation of karst landscapes in southwestern China.Principal component analysis(PCA), independent sample t-tests, and niche differentiation using bioclimatic variables based on locations of occurrence suggested that Paramesotriton habitat conditions in the three current regions(West, South,and East) differ significantly, with different levels of climatic niche differentiation. Species distribution model(SDM) predictions indicated that the most suitable distribution areas for the P. caudopunctatus and P. chinensis species groups are western and southern/eastern areas of southern China. This study increases our knowledge of the taxonomy,biodiversity, origin, and suitable distribution areas of the genus Paramesotriton based on phylogenetic,biogeographic, and species distribution models.

Red Palm Weevil, Rhynchophorus ferrugineus （Olivier）： Economic Importance, Biology, Biogeography and Integrated Pest Management

The Red Palm Weevil （RPW）, Rhynchophorus ferrugineus （Olivier）, （Coleoptera, Curculionidae, Rhynchophorinae）, is an invasive species that is originated from Southeast Asia. It has.invaded Middle East and several countries of the Mediterranean Basin during the last three decades where it attacks palm trees. During the last three decades, multiple introductions of RPW to the Middle East, Europe and Caribbean （Island of Curacao, Netherland Antilles）, Lebanon and United States of America （Laguna Beach, Orange County, California） （USA） have occurred and the RPW is now a serious pest of many palm species. Duration of all life parameters varies significantly where the entire life cycle takes about 45 to 298 days. Different artificial diets were developed and were tested for mass rearing of RPW. Control of RPW is difficult due to the concealed nature of the life cycle of the pest. Integrated Pest Management （IPM） strategy has been applied successfully to deal with RPW problem. The IPM strategy consists of various preventive and curative methods; those methods were categorized in nine categories in this review. The main objective of this work was to review the existing knowledge on RPW＇s different aspects, with an ultimate aim of revealing the actual situation of the research on RPW.

Optimizing Feedforward Neural Networks Using Biogeography Based Optimization for E-Mail Spam Identification

Spam e-mail has a significant negative impact on individuals and organizations, and is considered as a serious waste of resources, time and efforts. Spam detection is a complex and challenging task to solve. In literature, researchers and practitioners proposed numerous approaches for automatic e-mail spam detection. Learning-based filtering is one of the important approaches used for spam detection where a filter needs to be trained to extract the knowledge that can be used to detect the spam. In this context, Artificial Neural Networks is a widely used machine learning based filter. In this paper, we propose the use of a common type of Feedforward Neural Network called Multi-Layer Perceptron (MLP) for the purpose of e-mail spam identification, where the weights of this network model are found using a new nature-inspired metaheuristic algorithm called Biogeography Based Optimization (BBO). Experiments and results based on two different spam datasets show that the developed MLP model trained by BBO gets high generalization performance compared to other optimization methods used in the literature for e-mail spam detection.

Diversifying on the Ark:multiple new endemic lineages of dwarf geckos from the Western Ghats provide insights into the systematics and biogeography of South Asian Cnemaspis(Reptilia:Squamata)

The highly speciose gekkonid genus Cnemaspis Strauch,1887 is polyphyletic,with three distantly related and geographically isolated clades from Africa,South Asia(SA),and Southeast Asia.At present,there are 85 known species within SA Cnemaspis,although the number continues to increase rapidly with focused surveys and rigorous taxonomic work.Recent studies have provided valuable insights into the diversity and evolutionary history of SA Cnemaspis;however,most of these studies lack sufficient sampling in the Western Ghats(WG),where the genus has its greatest diversity.We addressed this research gap by conducting extensive sampling across the WG and re-examining museum specimens,thus providing a systematic account of various extant Cnemaspis species along with their distribution and natural history.We described 12 new species and a southern WG endemic clade of SA Cnemaspis.Ten of the newly described species are endemic to the forests of the southern WG.We also identified 10 well-supported subclades that can be separated across morphological,geographic,and phylogenetic axes.A time-calibrated phylogeny and ancestral area reconstructions confirmed the Paleocene origin of SA Cnemaspis in the WG and provide insights into its evolutionary history and biogeography.The discovery of multiple endemic and deeply divergent lineages further highlights the evolutionary significance of the WG for lizards.

Phylogeny and biogeography of Maianthemum(Asparagaceae:Nolinoideae)revisited with emphasis on its divergence pattern in SW China

Maianthemum is a genus with more than 35 species from the tribe Polygonateae(Asparagaceae),widely distributed between North to Central Americas and eastern Asia with high diversity in the easternHimalayas to the Hengduan Mountains of SW China.Although most species from SW China form a well-supported clade,phylogenetic relationships within this clade remain unclear.With a broad level of taxon sampling and an extensive character sampling fromeight DNA regions,this study intends to revisit the phylogeny and biogeography of the genus to better understand the divergence patterns of species from SW China.Phylogenetic results suggested the monophyly of Maianthemum with recognition of nine strongly supported clades,but backbone relationships among these clades remained largely uncertain.For the SWChina clade,individuals from the same species are grouped into different lineages.Our results revealed that the fast radiation of the SWChina cladewas occurred in the eastern Himalayas,followed by subsequent radiation in the Hengduan Mountains in the Pliocene.Intercontinental disjunctions of Maianthemum in the Northern Hemisphere appear to have occurred multiple times during the late Miocene to the Pliocene,likely resulted by a combination of both vicariance and long-distance dispersal events.

A preliminary molecular historical biogeography of Caragana (Leguminosae) based on ITS and trnL-F DNA sequence data

The nrDNA internal transcribed spacer (ITS) and cpDNA trnL-F internal spacer (IGS) sequence data of Caragana eight species and one outgroup Halimodendron halodendron, was employed to reconstruct a phylogenetic tree, then the area relationship was analyzed by means of component analysis (CA), Brooks parsimony analysis (BPA), and dispersal-vicariance analysis (DIVA), six areas were selected from two divided distributions of East Asia and Tethys in Caragana. The phylogenetic tree indicated that there were three distinctive groups, which were attributed to some morphological characters, first with pinnate foliage and deciduous rachis, second with palmate foliage and persistent sclerotic stick rachis, and third with pinnate foliage and persistent sclerotic stick rachis. The results of CA and BPA illustrated general area relationships. An explicit area relationship should be Altai-Sayan, Far East NE China and North China (Hengduan Mountains). DIVA recognized several explanatory vicariance and dispersal events. As the scenario of Caragana distribution pattern, it looks like the vicariance versus dispersal plays more important role. In vicaraince, there are not only the isolated far-distance vicariance, but also the adjacent vicariance especially a vicariance between Hengduan Mountains and North China.

Benthic microbial biogeography along the continental shelf shaped by substrates from the Changjiang River plume

Coastal zones are active reactors of continental material including that transported by rivers via a series of microbiota-mediated reactions. Nevertheless, current knowledge of the ecology and functioning of the microbiota in coastal areas affected by large riverine inputs remains insufficient on a global scale. Here, an investigation on sediment microbial composition, including taxonomy and metabolic network, as well as their relationship with major benthic reaction substrates, namely carbon, nitrogen, sulphur and phosphorus, was conducted in the continental shelf affected by the spread of the Changjiang River plume. Surface sediment samples(48 samples)were collected during March 2018, obtaining a mean Operational Taxonomic Units(OTUs) number of 3 341.Proteobacteria, Acidobacteria and Actinobacteria were abundant phyla in the studied sediments. Bray-Curtis distance analysis classified the 48 samples into 4 clusters(MG1 to MG4) at the phylum-level. MG1 and MG2 are found near the river mouth, receiving substantial land-derived particles from the Changjiang River runoff.Particle-attached microbes may be settled in these regions and influenced the observed sediment microbial diversity and biomass, e.g., increased Crenarchaeota relative abundance. The relative enrichment of these two groups in heterotrophic microbes further suggests a reliance of benthic microbiota on substrates with terrestrial origin, particularly specialized on processing sulphur-rich substrates. Regions MG3 and MG4 are located in the outer margin of the area affected by the Changjiang River plume, mainly fed by settling pelagic particles from phytoplankton. Compared to MG1 and MG2, a significant increase in the abundance of Thaumarcheota(phylumlevel) and Nitrosopumilus(genus-level) was found in MG3, suggesting nitrogen-related transformations as the key reactions to sustain microbial metabolism in this region. Coupled with the identified variations in the taxonomic composition, significant differences in the keystone taxa between MG1/MG2 and MG3/MG4 were identified via OTU co-occurrence analyses. A higher abundance of Actinobacteria, Thaumarchaeota and Acidobacteria in MG3 and MG4 reinforced the identified spatial variability in benthic metabolism and highlighted the significance of substrate inputs on the sediment microbial structure and biogeography.