Historical biogeography and evolutionary diversification of Lilium(Liliaceae): New insights from plastome phylogenomics

Here, we infer the historical biogeography and evolutionary diversification of the genus Lilium. For this purpose, we used the complete plastomes of 64 currently accepted species in the genus Lilium(14plastomes were newly sequenced) to recover the phylogenetic backbone of the genus and a timecalibrated phylogenetic framework to estimate biogeographical history scenarios and evolutionary diversification rates of Lilium. Our results suggest that ancient climatic changes and geological tectonic activities jointly shaped the distribution range and drove evolutionary radiation of Lilium, including the Middle Miocene Climate Optimum(MMCO), the late Miocene global cooling, as well as the successive uplift of the Qinghai-Tibet Plateau(QTP) and the strengthening of the monsoon climate in East Asia during the late Miocene and the Pliocene. This case study suggests that the unique geological and climatic events in the Neogene of East Asia, in particular the uplift of QTP and the enhancement of monsoonal climate, may have played an essential role in formation of uneven distribution of plant diversity in the Northern Hemisphere.

Plant diversity in Yunnan:Current status and future directions

Yunnan,located in southwestern China,harbors more than 19,000 higher plants,which represents the highest plant diversity in the country.However,plant diversity in Yunnan faces enormous threats today,including habitat destruction and fragmentation,environmental pollution,and over-exploitation of natural resources.Despite recent efforts to protect biodiversity,there are still thousands of threatened species,some of which have become extinct.We analyzed available data to gain a greater understanding of plant diversity and the status of plant conservation in Yunnan.We found that southern,southeastern,and northwestern Yunnan are hotspots of total species,endemic species,specimens,new species and threatened species,whereas southeastern Yunnan is a hotspot for plant species with extremely small populations.Moreover,we found that there are still conservation gaps and poorly protected areas in central,eastern,and northeastern Yunnan.We conclude that conservation of plant diversity in Yunnan requires modern field investigation,systematic research,the development of comprehensive databases,and government support.We recommend that conservationists pay more attention to building and improving functional protection systems and popularizing science.

Spatial phylogenetics of two topographic extremes of the Hengduan Mountains in southwestern China and its implications for biodiversity conservation

Previous attempts to elucidate the drivers of speciation mechanisms and spatial distribution patterns of biodiversity in mountain regions have treated different floras within a single geological region as one flora,ignoring the potential contributions of high habitat/ecosystem heterogeneity.Furthermore,current conservation strategies largely focus on forest ecosystems and/or specific flagship species,ignoring marginal ecosystems,leaving species in these ecosystems at risk.Here,we compared the spatial patterns of biodiversity and the potential drivers of these patterns in the river valley and subnival ecosystems of the Hengduan Mountains region(HDM)in southwestern China.Specifically,we compared spatial patterns of diversity,endemism,and threatened species in these ecosystems based on both traditional measurements and recent phylogenetic approaches.We then examined how those patterns were related to environmental factors and human activity in these same regions.We found that the middle-southern HDM supports the highest diversity and endemism for the river valley and subnival ecosystems;however,the distribution patterns of neo-and paleo-endemism in these two ecosystems differ.Regression models indicate that habitat diversity and paleo-climatic fluctuation are important drivers of diversity and endemism for these two ecosystems.Temperature and precipitation,however,showed different influences on the spatial patterns in different ecosystems.Categorical analysis of neo-and paleoendemism(CANAPE)indicated that most endemism centers are not covered by current nature reserves.Moreover,the intensity of human activity is highest in the southern and southeastern HDM,which coincides with the distribution patterns of diversity,mixed-endemism and high-priority(and threatened)species.These findings suggest that different floras within a single geographic/floristic region respond differently to environmental factors and show different spatial phylogenetic patterns.We,therefore,recommend that future research into the drivers of biodiversity consider the contributions of various ecosystem types within a single geological region.This study also provides a theoretical basis for protecting habitat diversity.Our work confirms that current conservation efforts are insufficient to protect ecosystem diversity in the river valley and subnival ecosystems of the Hengduan Mountains.Therefore,we recommend the establishment of nature reserves in the regions identified in this study;furthermore,we strongly recommend improving current and establishing new management policies for biodiversity conservation in this region.

Historical development of karst evergreen broadleaved forests in East Asia has shaped the evolution of a hemiparasitic genus Brandisia(Orobanchaceae)

Brandisia is a shrubby genus of about eight species distributed basically in East Asian evergreen broadleaved forests(EBLFs),with distribution centers in the karst regions of Yunnan,Guizhou,and Guangxi in southwestern China.Based on the hemiparasitic and more or less liana habits of this genus,we hypothesized that its evolution and distribution were shaped by the development of EBLFs there.To test our hypothesis,the most comprehensive phylogenies of Brandisia hitherto were constructed based on plastome and nuclear loci(nrDNA,PHYA and PHYB);then divergence time and ancestral areas were inferred using the combined nuclear loci dataset.Phylogenetic analyses reconfirmed that Brandisia is a member of Orobanchaceae,with unstable placements caused by nuclear-plastid incongruences.Within Brandisia,three major clades were well supported,corresponding to the three subgenera based on morphology.Brandisia was inferred to have originated in the early Oligocene(32.69 Mya)in the Eastern Himalayas-SW China,followed by diversification in the early Miocene(19.45 Mya)in karst EBLFs.The differentiation dates of Brandisia were consistent with the origin of keystone species of EBLFs in this region(e.g.,Fagaceae,Lauraceae,Theaceae,and Magnoliaceae)and the colonization of other characteristic groups(e.g.,Gesneriaceae and Mahonia).These findings indicate that the distribution and evolution of Brandisia were facilitated by the rise of the karst EBLFs in East Asia.In addition,the woody and parasitic habits,and pollination characteristics of Brandisia may also be the important factors affecting its speciation and dispersal.

Fossil fruits of Firmiana and Tilia from the middle Miocene of South Korea and the efficacy of the Bering land bridge for the migration of mesothermal plants

Determining whether the high-latitude Bering land bridge(BLB)was ecologically suitable for the migration of mesothermal plants is significant for Holarctic phytogeographic inferences.Paleobotanical studies provide a critical source of data on the latitudinal positions of different plant lineages at different times,permitting assessment of the efficacy of the BLB for migration.Here we report exceptionally preserved fossils of Firmiana and Tilia endochrysea from the middle Miocene of South Korea.This represents a new reliable record of Firmiana and the first discovery of the T.endochrysea lineage in the fossil record of Asia.The occurrence of these fossils in South Korea indicates that the two lineages had a distribution that extended much farther north during the middle Miocene,but they were still geographically remote from the BLB.In light of the broader fossil record of Asia,our study shows that,in the middle Miocene,some mesothermal plants apparently inhabited the territory adjacent to the BLB and thus they were possibly capable of utilizing the BLB as a migratory corridor.Some other mesothermal plants,such as Firmiana and the T.endochrysea lineages,however,are restricted to more southern regions relative to the BLB based on current fossil evidence.These lineages may have been ecologically unable to traverse the BLB,which raises questions about the efficacy of the BLB as a universal exchange route for mesothermal plants between Asia and North America during the middle Miocene.

Central Asia revealed as a key area in evolution of Eremurus (Asphodelaceae)

Eremurus was described at the beginning of the 19th century.However,due to limited sampling and the small number of gene markers to date,its phylogeny and evolution are largely unknown.In this study,we analyzed plastomes from 27 species belonging to 2 subgenera and 3 sections of Eremurus,which are found in Central Asia(its center of diversity)and China.We also analyzed nuclear DNA ITS of 33 species,encompassing all subgenera and sections of the genus in Central Asia,southwest Asia and China.Our findings revealed that the genus was monophyletic,although both subgenera Eremurus and Henningia were found to be paraphyletic.Both plastome and nrDNA-based phylogenetic trees had three clades that did not reflect the current taxonomy of the genus.Our biogeographical and time-calibrated trees suggest that Eremurus originated in the ancient Tethyan area in the second half of the Eocene.Diversification of Eremurus occurred from the early Oligocene to the late Miocene.Paratethys Sea retreat and several orogenetic events,such as the progressive uplift of the Qinghai-Tibet Plateau and surrounding mountain belts(Altai,Pamir,Tian Shan),caused serious topographic and climate(aridification)changes in Central Asia that may have triggered a split of clades and speciation.In this transformed Central Asia,speciation proceeded rapidly driven mainly by vicariance caused by numerous mountain chains and specialization to a variety of climatic,topographic and soil conditions that exist in this region.

Genetic analyses of ancient tea trees provide insights into the breeding history and dissemination of Chinese Assam tea(Camellia sinensis var.assamica)

Chinese Assam tea(Camellia sinensis var.assamica)is an important tea crop with a long history of cultivation in Yunnan,China.Despite its potential value as a genetic resource,its genetic diversity and domestication/breeding history remain unclear.To address this issue,we genotyped 469 ancient tea plant trees representing 26 C.sinensis var.assamica populations,plus two of its wild relatives(six and three populations of C.taliensis and C.crassicolumna,respectively)using 16 nuclear microsatellite loci.Results showed that Chinese Assam tea has a relatively high,but comparatively lower gene diversity(H_(S)=0.638)than the wild relative C.crassicolumna(H_S=0.658).Clustering in STRUCTURE indicated that Chinese Assam tea and its two wild relatives formed distinct genetic groups,with considerable interspecific introgression.The Chinese Assam tea accessions clustered into three gene pools,corresponding well with their geographic distribution.However,New Hybrids analysis indicated that 68.48%of ancient Chinese Assam tea plants from Xishuangbanna were genetic intermediates between the Puer and Lincang gene pools.In addition,10%of the ancient Chinese Assam tea individuals were found to be hybrids between Chinese Assam tea and C.taliensis.Our results suggest that Chinese Assam tea was domesticated separately in three gene pools(Puer,Lincang and Xishuangbanna)in the Mekong River valley and that the hybrids were subsequently selected during the domestication process.Although the domestication history of Chinese Assam tea in southwestern Yunnan remains complex,our results will help to identify valuable genetic resources that may be useful in future tea breeding programs.

Molecular phylogeny and taxonomy of Phlomoides(Lamiaceae subfamily Lamioideae)in China:Insights from molecular and morphological data

Phlomoides,with 150-170 species,is the second largest and perhaps most taxonomically challenging genus within the subfamily Lamioideae(Lamiaceae).With about 60 species,China is one of three major biodiversity centers of Phlomoides.Although some Phlomoides species from China have been included in previous molecular phylogenetic studies,a robust and broad phylogeny of this lineage has yet to be completed.Moreover,given the myriad new additions to the genus,the existing infrageneric classification needs to be evaluated and revised.Here,we combine molecular and morphological data to investigate relationships within Phlomoides,with a focus on Chinese species.We observed that plastid DNA sequences can resolve relationships within Phlomoides better than nuclear ribosomal internal and external transcribed spacer regions(nrITS and nrETS).Molecular phylogenetic analyses confirm the monophyly of Phlomoides,but most previously defined infrageneric groups are not monophyletic.In addition,morphological analysis demonstrates the significant taxonomic value of eight characters to the genus.Based on our molecular phylogenetic analyses and morphological data,we establish a novel section Notochaete within Phlomoides,and propose three new combinations as well as three new synonyms.This study presents the first molecular phylogenetic analyses of Phlomoides in which taxa representative of the entire genus are included,and highlights the phylogenetic and taxonomic value of several morphological characters from species of Phlomoides from China.Our study suggests that a taxonomic revision and reclassification for the entire genus is necessary in the future.

Eco-evolutionary evidence for the global diversity pattern of Cycas(Cycadaceae)

The evolution of the latitudinal diversity gradient(LDG),characterized by a peak in diversity toward the tropics,has captured significant attention in evolutionary biology and ecology.However,the inverse LDG(i-LDG)mechanism,wherein species richness increases toward the poles,remains inadequately explored.Cycads are among one of the oldest lineages of extant seed plants and have undergone extensive diversification in the tropics.Intriguingly,the extant cycad abundance exhibits an i-LDG pattern,and the underlying causes for this phenomenon remain largely elusive.Here,using 1,843 nuclear genes from a nearly complete sampling,we conducted comprehensive phylogenomic analyses to establish a robust species-level phylogeny for Cycas,the largest genus within cycads.We then reconstructed the spatial-temporal dynamics and integrated global environmental data to evaluate the roles of species ages,diversification rates,contemporary environment,and conservatism to ancestral niches in shaping the i-LDG pattern.We found Cycas experienced decreased diversification rates,coupled with the cooling temperature since its origin in the Eocene from continental Asia.Different regions have distinctively contributed to the formation of i-LDG for Cycas,with the northern hemisphere acting as evolutionary museums and the southern hemisphere serving as cradles.Moreover,water-related climate variables,specifically precipitation seasonality and potential evapotranspiration,were identified as paramount factors constraining Cycas species richness in the rainforest biome near the equator.Notably,the adherence to ancestral monsoonal climates emerges as a critical factor in sustaining the diversity pattern.This study underscores the imperative of integrating both evolutionary and ecological approaches to comprehensively unravel the mechanisms underpinning global biodiversity patterns.

Distributional responses to climate change for alpine species of Cyananthus and Primula endemic to the Himalaya-Hengduan Mountains

Global warming increases the vulnerability of plants, especially alpine herbaceous species, to local extinction. In this study, we collected species distribution information from herbarium specimens for ten selected Cyananthus and Primula alpine species endemic to the Himalaya-Hengduan Mountains(HHM).Combined with climate data from WorldClim, we used Maximum Entropy Modeling(MaxEnt) to project distributional changes from the current time period to 2070. Our predictions indicate that, under a wide range of climate change scenarios, the distributions of all species will shift upward in elevation and northward in latitude; furthermore, under these scenarios, species will expand the size of their range. For the majority of the species in this study, habitats are available to mitigate upward and northward shifts that are projected to be induced by changing climate. If current climate projections, however, increase in magnitude or continue to increase past our projection dates, suitable habitat for future occupation by alpine species will be limited as we predict range contraction or less range expansion for some of the species under more intensified climate scenarios. Our study not only underscores the value of herbarium source information for future climate model projections but also suggests that future studies on the effects of climate change on alpine species should include additional biotic and abiotic factors to provide greater resolution of the local dynamics associated with species persistence under a warming climate.

Genetic diversity and population structure of Hibiscus aridicola, an endangered ornamental species in dry-hot valleys of Jinsha River

Hibiscus aridicola is an endangered ornamental shrub of the family Malvaceae that is endemic to the dryhot valleys of Jinsha River in southwestern China.This species is a typical plant species with extremely small populations(PSESP).To support and monitor future conservation,develop management measures,and genotype this species,we performed extensive field studies together with genetic analyses.Specifically,we screened eleven microsatellite loci of 69 individuals of H.aridicola from four accessions.The population genetics analyses indicated that H.aridicola possesses high genetic diversity at both the population(0.6962-0.7293)and species level(0.7837)compared to other endemic/endangered species in China.The low differentiation of populations(Fst=0.0971)and the high gene flow between populations of H.aridicola(Nm=2.3236)could be due to its distribution along rivers in the hot-valleys of the Jinsha River and the wind-mediated dispersal of its seeds.Furthermore,the genetic diversity of H.aridicola is slightly positively correlated with geographic distance.Two populations are undergoing a genetic bottleneck,and require more specific attention from conservationists.Additionally,our analyses of the population genetics of H.aridicola demonstrate that the declines in populations are not the result of the internal genetics of these populations but due to external human activities over the past decades.

Elevational patterns of functional diversity and trait of Delphinium(Ranunculaceae)in Hengduan Mountains,China

Elevational patterns of trait occurrence and functional diversity provide an important perspective for understanding biodiversity.However,previous studies have mostly examined functional diversity at the community scale.Here,we examined large-scale patterns of trait occurrence and functional diversity in Delphinium along an elevational gradient from 1000 to 5700 m in the Hengduan Mountains,SW China.Elevational distribution and trait data of 102 Delphinium species were compiled to evaluate the patterns of interspecific traits,species richness,and functional diversity.We found that the distribution of species richness showed a unimodal curve that peaked between 3500 and 4000 m;functional diversity and traits showed different patterns along an elevational gradient The functional diversity increased at a lower rate along an elevation gradient,whereas species richness continued to increase.Species with large ranges and non-endemic species were most affected by geometric constraints.Richness of species endemic to the Hengduan Mountains peaked at higher elevations,likely due to increased speciation and restricted dispersion under alpine conditions.We conclude that the middle elevation region is not only the functionally richest but also the most functionally stable region for Delphinium,which could be insurance against environmental change.Extreme conditions and strong environmental filters in an alpine environment may cause the convergence of species traits,which could relate to reducing nutrient trait investment and increasing reproductive trait investment.We conclude that large-scale studies are consistent with previous studies at the community scale.This may indicate that the relationship between functional diversity and species richness across different scales is the same.

Involucre fossils of Carpinus,a northern temperate element,from the Miocene of China and the evolution of its species diversity in East Asia

East Asia has long been recognized as a major center for temperate woody plants diversity.Although several theories have been proposed to explain how the diversity of these temperate elements accumulated in the region,the specific process remains unclear.Here we describe six species of Carpinus,a typical northern hemisphere temperate woody plant,from the early Miocene of the Maguan Basin,southwestern China,southern East Asia.This constitutes the southernmost,and the earliest occurrence that shows a high species diversity of the genus.Together with other Carpinus fossil records from East Asia,we show that the genus had achieved a high diversity in East Asia at least by the middle Miocene.Of the six species here described,three have become extinct,indicating that the genus has experienced apparent species loss during its evolutionary history in East Asia.In contrast,the remaining three species closely resemble extant species,raising the possibility that these species may have persisted in East Asia at least since the early Miocene.These findings indicate that the accumulation of species diversity of Carpinus in East Asia is a complex process involving extinction,persistence,and possible subsequent speciation.

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.

Expansion and expression diversity of FAR1/FRS-like genes provides insights into flowering time regulation in roses

Roses are important horticultural plants with enormous diversity in flowers and flowering behavior.However,molecular regulation of flowering time variation in roses remains poorly characterized.Here,we report an expansion of the FAR1/FRS-like genes that correlates well with the switch to prostrate-toerect growth of shoots upon flowering in Rosa wichuraiana‘Basye's Thornless'(BT).With the availability of the high-quality chromosome-level genome assembly for BT that we developed recently,we identified 91 RwFAR1/FRS-like genes,a significant expansion in contrast to 52 in Rosa chinensis‘Old Blush’(OB),a founder genotype in modern rose domestication.Rose FAR1/FRS-like proteins feature distinct variation in protein domain structures.The dispersed expansion of RwFAR1/FRS-like genes occurred specifically in clade I and II and is significantly associated with transposon insertion in BT.Most of the RwFAR1/FRS-like genes showed relatively higher expression level than their corresponding orthologs in OB.FAR1/FRS-like genes regulate light-signaling processes,shade avoidance,and flowering time in Arabidopsis thaliana.Therefore,the expansion and duplication of RwFAR1/FRS-like genes,followed by diversification in gene expression,might offer a novel leverage point for further understanding the molecular regulation of the variation in shoot-growth behavior and flowering time in roses.

Patterns of phylogenetic relatedness of non-native plants across the introduction-naturalization-invasion continuum in China

Human activities have caused the exchange of species among different parts of the world.When introduced species become naturalized and invasive,they may cause great negative impacts on the environment and human societies,and pose significant threats to biodiversity and ecosystem structure.Knowledge on phylogenetic relatedness between native and non-native species and among non-native species at different stages of species invasion may help for better understanding the drivers of species invasion.Here,I analyze a comprehensive data set including both native and non-native angiosperm species in China to determine phylogenetic relatedness of introduced species across a full invasion continuum(from introduction through naturalization to invasion).This study found that(1) introduced plants are a phylogenetically clustered subset of overall(i.e.native plus non-native) angiosperm flora,(2) naturalized plants are a phylogenetically clustered subset of introduced plants,and(3) invasive plants are a phylogenetically clustered subset of naturalized plants.These patterns hold regardless of spatial scales examined(i.e.national versus provincial scale) and whether basal-or tip-weighted metric of phylogenetic relatedness is considered.These findings are consistent with Darwin's preadaptation hypothesis.

RAD-sequencing improves the genetic characterization of a threatened tree peony(Paeonia ludlowii)endemic to China:Implications for conservation

Compared with traditional genetic markers,genomic approaches have proved valuable to the conservation of endangered species.Paeonia ludlowii having rarely and pure yellow flowers,is one of the world’s most famous tree peonies.However,only several wild populations remain in the Yarlung Zangbo Valley(Nyingchi and Shannan regions,Xizang)in China due to increasing anthropogenic impact on the natural habitats.We used genome-wide single nucleotide polymorphisms to elucidate the spatial pattern of genetic variation,population structure and demographic history of P.ludlowii from the fragmented region comprising the entire range of this species,aiming to provide a basis for conserving the genetic resources of this species.Unlike genetic uniformity among populations revealed in previous studies,we found low but varied levels of intra-population genetic diversity,in which lower genetic diversity was detected in the population in Shannan region compared to those in Nyingzhi region.These spatial patterns may be likely associated with different population sizes caused by micro-environment differences in these two regions.Additionally,low genetic differentiation among populations(Fst=0.0037)were detected at the species level.This line of evidence,combined with the result of significant genetic differentiation between the two closest populations and lack of isolation by distance,suggested that shared ancestry among now remnant populations rather than contemporary genetic connectivity resulted in subtle population structure.Demographic inference suggested that P.ludlowii probably experienced a temporal history of sharp population decline during the period of Last Glacial Maximum,and a subsequent bottleneck event resulting from prehistoric human activities on the Qinghai-Tibet Plateau.All these events,together with current habitat fragment and excavation might contribute to the endangered status of P.ludlowii.Our study improved the genetic characterization of the endangered tree peony(P.ludlowii)in China,and these genetic inferences should be considered when making different in situ and ex situ conservation actions for P.ludlowii in this evolutionary hotspot region.

Karyomorphology of three endemic plants(Brassicaceae:Euclidieae and Arabideae)from the Qinghai-Tibet Plateau and its significance

In the paper,chromosome number and karyotype of three endemic genera from China are reported for the first time.Our results show that Anzhengxia yechengnica has a karyotype formula2 n=2 x=14=6 m+8 sm and belongs to Stebbins-3 A;Shangrilaia nana karyotype formula is2 n=2 x=14=10 m+4 sm(2 sat) and belongs to Stebbins-1 A;Baimashania pulvinata karyotype formula is 2 n=2 x=16=12 m(2 sat)+4 sm and belongs to Stebbins-1 A.Anzhengxia and Shangrilaia are monospecific genera belonging to tribe Euclidieae and both have a basic chromosome x=7.Baimashania,which belongs to tribe Arabideae,has two species which have a basic chromosome x=8.The implications of these cytological data are compared with morphological support and the implications for each tribe are discussed.We also summarize chromosomal number variation and its systematic implications of two tribes from the Qinghai-Tibet Plateau.

Seedling survival after simulating grazing and drought for two species from the Pamirs,northwestern China

For plant populations to persist,seedling recruitment is essential,requiring seed germination,seedling survival and growth.Drought and grazing potentially reduce seedling recruitment via increased mortality and reduced growth.We studied these seederelated processes for two species indigenous to the Pamir Mountains of Xinjiang in northwestern China:Saussurea glacialis and Plantago lessingii.Seeds collected from Taxkorgan,Xinjiang,had a viability rate of 15.8%for S.glacialis but 100%for P.lessingii.Of the viable seeds,the highest germination rates were 62.9%for S.glacialis and 45.6%for P.lessingii.In a greenhouse experiment,we imposed a series of stressful conditions,involving a combination of simulated grazing and drought events.These had the most severe impact on younger seedlings.Modelling showed that 89%of S.glacialis mortality was due to early simulated grazing,whereas 80%of P.lessingii mortality was due to early simulated drought.Physiological differences could contribute to their differing resilience.S.glacialis may rely on water storage in leaves to survive drought events,but showed no shifts in biomass allocation that would improve grazing tolerance.P.lessingii appears more reliant on its root system to survive grazing,but the root reserves of younger plants could be insufficient to grow deeper in response to drought.After applying all mortality factors,17.7 seedlings/parent of P.lessingii survived,while only<0.1 seedlings/parent of S.glacialis survived,raising concerns for its capacity to persist in the Pamirs.Inherent genetic differences may underlie the two species’contrasting grazing and drought responses.Thus,differing conservation strategies are required for their utilization and protection.

Molecular and morphological evidence for a new species of Isodon (Lamiaceae) from southern China

Isodon brevipedunculatus,a new species from southern China,is described and illustrated.The phylogenetic position of the new species within the genus was analyzed based on two nuclear ribosomal DNA regions and an ingroup sampling of about 80%of Asian species of Isodon.The results show that I.brevipedunculatus is recovered in a clade that consists of species mainly with glandular mericarps and that are distributed in the Sino-Japanese region.Combining molecular and geographical evidence,our study reveals that I.brevipedunculatus is most closely related to Isodon amethystoides and Isodon bifidocalyx,but differs from the former in lamina shape,number of flowers per cyme,and peduncle length,and from the latter in lamina indumentum,calyx morphology,and corolla length.