Intercontinental comparison of phylogenetic relatedness in introduced plants at the transition from naturalization to invasion:A case study on the floras of South Africa and ChinaOA

Invasive species may pose significant threats to biodiversity and ecosystem structure and functioning.The number of introduced species that have become invasive is substantial and is rapidly increasing.Identifying potentially invasive species and preventing their expansion are of critical importance in invasion ecology.Phylogenetic relatedness between invasive and native species has been used in predicting invasion success.Previous studies on the phylogenetic relatedness of plants at the transit...     

Response of Polygonum viviparum species and community level to long-term livestock grazing in alpine shrub meadow in Qinghai-Tibet Plateau

Grazing by domestic herbivores is generally recognized as a major ecological factor and an important evolutionary force in grasslands. Grazing has both extensive and profound effects on individual plants and communities. We investigated the response patterns of Polygonum viviparum species and the species diversity of an alpine shrub meadow in response to long-term livestock grazing by a field manipulative experiment controlling livestock numbers on the Qinghai-Tibet Plateau in China. Here, we hypothesize that within a range of grazing pressure, grazing can alter relative allocation to different plant parts without changing total biomass for some plant species if there is life history trade-offs between plant traits. The same type of communities exposed to different grazing pressures may only alter relative species' abundances or species composition and not vary species diversity because plant species differ in resistant capability to herbivory. The results show that plant height and biomass of different organs differed among grazing treatments but total biomass remained constant. Biomass allocation and absolute investments to both reproduction and growth decreased and to belowground storage increased with increased grazing pressure, indicating the increasing in storage function was attained at a cost of reducing reproduction of bulbils and represented an optimal allocation and an adaptive response of the species to long-term aboveground damage. Moreover, our results showed multiform response types for either species groups or single species along the gradient of grazing Intensity. Heavy grazing caused a 13.2％ increase in species richness. There was difference in species composition of about 18％--20％ among grazing treatment. Shannon-Wiener (H') diversity index and species evenness (E) index did not differ among grazing treatments. These results support our hypothesis.     

Phylogenetic Relationship of Dendranthema （DC.） Des Moul. Revealed by Fluorescent In Situ Hybridization

Phylogenetic relationships of the different species in the genus Dendranthema (DC.) Des Moul. were estimated based on chromosome fluorescent in situ hybridization (FISH) with 18S-26S rDNA of Arabidopsis and genomic DNA of Dendranthema as probes. The results revealed that there was no positive correlation between the number of nuclear organization region (NOR) loci and the ploidy of Dendranthema.The exact cytogenetic information of NORs about 14 operational taxonomic units (OTUs) indicated that D.vestitum (Hemsl.) Ling et Shih was closer to the cultivars than other putative species, whereas D. zawadskii (Herb.) Tzvel. was the most distinct. The ambiguously distributed signals of genomic in situ hybridization (GISH) with genomic DNA of lower ploidy species as probes suggested that different genomes among Dendranthema were mixed. The result also indicated the limitation of GISH in studies on the phylogenetic relationships of the different species in this genus Dendranthema and on the origin of cultivated chrysanthemums. Based on these results and previous research, the origin of Chinese cultivated chrysanthemum is discussed.     

Remote sensing and geographic information systems in the spatial temporal dynamics modeling of infectious diseases

Similar to species immigration or exotic species invasion,infectious disease transmis-sion is strengthened due to the globalization of human activities. Using schistosomiasis as an exam-ple,we propose a conceptual model simulating the spatio-temporal dynamics of infectious diseases. We base the model on the knowledge of the interrelationship among the source,media,and the hosts of the disease. With the endemics data of schistosomiasis in Xichang,China,we demonstrate that the conceptual model is feasible; we introduce how remote sensing and geographic information systems techniques can be used in support of spatio-temporal modeling; we compare the different effects caused to the entire population when selecting different groups of people for schistosomiasis control. Our work illustrates the importance of such a modeling tool in supporting spatial decisions. Our mod-eling method can be directly applied to such infectious diseases as the plague,lyme disease,and hemorrhagic fever with renal syndrome. The application of remote sensing and geographic informa-tion systems can shed light on the modeling of other infectious disease and invasive species studies.     

A paradox: rapid evolution rates of germline-limited sequences are associated with conserved patterns of rearrangements in cryptic species of Chilodonella uncinata(Protista,Ciliophora)

Some of the most extreme genome wide rearrangements are found in ciliates, which are unique in possessing both germline micronucleus and somatic macronucleus in every cell/organism. A series of DNA rearrangement events, including DNA elimination, chromosomal fragmentation, gene unscrambling and alternative processing, happen during macronuclear development. To assess the molecular evolution of macronuclear and germline-limited sequences in different cryptic species of Chilodonella uncinata, we characterized the actin, α-tubulin and β-tubulin genes in the micronucleus and macronucleus genomes of USA-SC2 strain and compared them with other strains(i.e. cryptic species). Three main results are:(i) rearrangement patterns between germline and soma are conserved for each gene among the cryptic species of C. uncinata;(ii) in contrast, the germlinelimited regions are highly divergent in sequence and length among the cryptic species;(iii) pointer shifting is frequent among the cryptic species. We speculate that pointer sequences may serve as the buffer between the conserved macronuclear destined sequences and rapidly-evolving internal eliminated sequences. The data combined with previous studies demonstrate the plasticity of gene rearrangement among different groups of ciliates and add to the growing data for the role of genome rearrangements in species differentiation.     

Different paths to sexual size dimorphism in two praying mantids,Pseudomantis albofimbriata and Hierodula majuscula

Sexual size dimorphism （SSD） is widespread among diverse animal taxa and has attracted the attention of evolutionary biologists for over a century. SSD is likely to be adaptive and the result of divergent selection on different size optima for males and females, given their different roles in reproduction. The developmental trajectory leading to SSD may help us to understand how selection acts on male and female size. Here, we describe the growth and development of two Australian praying mantids, Pseudomantis albofimbriata and Hierodula majuscula including the number of moults, time to adulthood, size at each moult, and the degree of SSD. While both species exhibit the common pattern of female-biased SSD, the number of moults required for individuals to reach adulthood differed between males and females and between species. Despite their larger adult size, P. albofimbriata females require fewer moults and less time than males to reach adulthood, but are significantly larger than males from the second instar onwards. In contrast, H. majuscula males reached adulthood in fewer moults, and less time than females, however males and females did not differ in size until females went through their final moult into adulthood. H. majuscula also required more time and more moults to reach adulthood than 17. albofimbriata. We discuss these different developmental pathways in light of the existing knowledge of reproductive biology for each species. We also suggest that these differences may relate to the different phenologies that occur in strongly seasonal temperate environments compared with those in the tropics. This study provides evidence that SSD can result from two different patterns of growth and development in closely related species.     

Sex-specific facilitation and reproduction of the gynodioecious cushion plant Arenaria polytrichoides on the Himalaya-Hengduan mountains,SW ChinaOA

When benefiting other beneficiaries, cushion plants may reciprocally receive feedback effects. The feedback effects on different sex morphs, however, remains unclear. In this study, taking the gynodioecious Arenaria polytrichiodes as a model species, we aimed to assess the sex-specific facilitation intensity of cushion plant by measuring the beneficiary cover ratio, and to assess the potential costs in cushion reproductive functions by measuring the flower and fruit cover ratios. The total benef...     

Wind-dispersed seeds blur phylogeographic breaks:The complex evolutionary history of Populus lasiocarpa around the Sichuan BasinOA

The strength of phylogeographic breaks can vary among species in the same area despite being subject to the same geological and climate history due to differences in biological traits.Several important phylogeographic breaks exist around the Sichuan Basin in Southwest China but few studies have focused on wind-dispersed plants.Here,we investigated the phylogeographic patterns and the evolutionary history of Populus lasiocarpa,a wind-pollinated and wind-dispersed tree species with a circum-Sichua...     

Leaf hydraulics coordinated with leaf economics and leaf size in mangrove species along a salinity gradientOA

Independence among leaf economics,leaf hydraulics and leaf size confers plants great capability in adapting to heterogeneous environments.However,it remains unclear whether the independence of the leaf traits revealed across species still holds within species,especially under stressed conditions.Here,a suite of traits in these dimensions were measured in leaves and roots of a typical mangrove species,Ceriops tagal,which grows in habitats with a similar sunny and hot environment but different soi...     

Differences in Incubation Length and Hatchling Morphology among Five Species of Oviparous Phrynocephalus Lizards （Agamidae） from China

We incubated eggs of five Phrynocephalus species （P. albolineatus, P. axillaries, P. grumgrzimailoi, P. helioscopus and P. przewalskii） at three constant temperatures （24℃, 28℃ and 32℃） to examine differences in incubation length and hatchling morphology among species and among temperature treatments. We combined data from this study with those reported previously for P. frontalis and P. versicolor to examine whether embryonic stage at laying is a causal factor for interspecific variation in incubation length, and whether the phylogenetic relationship inferred from hatchling morphology is consistent with the relationship based on mitochondrial DNA data. Mean values for incubation length differed among the five species studied herein and, in all these five species, incubation length decreased at a decreasing rate as temperature increased. In none of the five species did hatchling size （snout-vent length and body mass） and other morphological variables differ among the three temperature treatments. The seven oviparous Phrynocephalus lizards found in China differ from each other in hatchling morphology, and embryonic stage at laying is a causal factor of inter- and intra-specific variation in incubation length. The phylogenetic relationship inferred from hatchling morphology is not always consistent with the currently known relationship based on mitochondrial DNA data. Data from this study and those reported previously allow the conclusion that any Phrynocephalus species may have its unique position along the axis defined by hatchling morphology.     

ISSR Analysis of the Genetic Diversity of the Endangered Species Sinopodophyllum hexandrum （Royle） Ying from Western Sichuan Province, China

Slnopodophyllum hexandrum （Royle） Ying Is an Important medicinal and endangered species. Inter-simple sequence repeats （ISSR） analysis was conducted on seven natural populations from western Slchuan Province to Investigate the genetic diversity of S. hexandrum. Leaf samples of 140 Individuals were collected. Of the 139 discernible fragments generated by 12 selected primers （among 100 primers）, 54 appeared to be polymorphlc. The percentage of polymorphlc bands （PPB） was 38.85% at the species level, and PPB within a population ranged from 7.91% to 23.74%. Low levels of genetic variation （He = 0.092, Ho = 0.142） and high levels of genetic differentiation among the populations （Gst= 62.25%） was detected on the basis of results from POPGENE and analysis of molecular variance （AMOVA）, respectively. Furthermore, the limited gene flow （Nm = 0.361） may result from biological characteristics, such as self-pollination and short distance seed dispersal. Based on the genetic and ecological Information available for S. hexandrum, we propose some appropriate strategies for the conservation of the endangered medicinal species in this region, namely rescuing and conserving the core populations for in situ conservation and sampling and preserving more populations with fewer Individuals from each population for ex situ conservation.     

A revision of Clematis sect. Atragene （Ranunculaceae）

Clematis sect. Atragene is revised in this paper based on the examination of a large number of herbarium specimens, extensive field observations, and morphometric analyses. Brief taxonomic history and geographical distribution of the section are given, the relationships among the species are discussed, and the evolutionary trends of some characters in the section are evaluated. The staminodes of the plants in this section may have evolved from the outer stamens with petaloid filaments and gradually disappearing anthers. Subsequently, they may have evolved in two different ways. One possibility is that the staminodes elongate and become lanceolate, as long as sepals, and their apices turn into attenuate. The other is that the staminodes are spathulate, but not elongating, as long as stamens, and their apices turn into retuse from obtuse and rounded. The evolutionary trend of sepals may be from thin to thick in texture, and the veins from non-prominent to prominent. As a result, five new series are established and nine species, two subspecies and nine varieties （including three new ranks） are recognized in this section. An identification key is provided, and each taxon is described and illustrated. Clematis sibirica and Clematis ochotensis are treated as subspecies of Clematis alpina due to their subtle differences and lack of, or few, overlapping distributions. Clematis fusijamana and Clematisfauriei are recognized as varieties of C. alpina ssp. ochotensis for the continuous variation of the velutinous strips on the sepal margins. Clematis iliensis is treated as variety of C. alpina ssp. sibirica for the continuous variation of leaf division types. Extensive variations in sepal color and basal caruncle size support degrading Clematis chiisanensis as a variety of Clematis koreana. The North American ser. Occientales may be primitive, whereas ser. Macropetalae may be the most advanced taxon in this section. Ser. Alpinae and ser. Koreanae are closely related to each other. However, the systematic position of ser.     

Computational approaches to understanding protein aggregation in neurodegeneration

The generation of toxic non-native protein conformers has emerged as a unifying thread among disorders such as Alzheimer＇s disease, Parkinson＇s disease, and amyotrophic lateral sclerosis. Atomic-level detail regarding dynamical changes that facilitate protein aggre- gation, as well as the structural features of large-scale ordered aggregates and soluble non-native oligomers, would contribute signifi- cantly to current understanding of these complex phenomena and offer potential strategies for inhibiting formation of cytotoxic species. However, experimental limitations often preclude the acquisition of high-resolution structural and mechanistic information for aggregating systems. Computational methods, particularly those combine both aU-atom and coarse-grained simulations to cover a wide range of time and length scales, have thus emerged as crucial tools for investigating protein aggregation. Here we review the current state of computational methodology for the study of protein self-assembly, with a focus on the application of these methods toward understanding of protein aggregates in human neurodegenerative disorders.     

Molecular differentiation of the microgastrine species commonly found in paddy fields from Southeast Asia,with additional data on their phylogeny （Hymenoptera：Braconidae）

Partial DNA sequences of three genes, that is, mitochondrial large ribosomal subunit (16S), nuclear large ribosomal subunit (28S D2) and mitochondrial NADH1 dehydrogenase (NADH1) gene, were sequenced from different microgas trine species(Braconidae: Microgastrinae) collected fresh from paddy fields. The DNA sequences were used to determine the extent of sequence variation among species in order to evaluate the specific status of each species. Cladistic analysis was also used to infer a phylogenetic relationship among these species. The results showed that sequence divergence among species of the same genus Cotesia was much lower than those among different genera, such as Cotesia, Exoryza and Apanteles; the sequence similarity of 16S rDNA and NADH 1 genes between Cotesia sp. and C. chilonis was higher than that between C. sp. and C. ruficrus.Phylogenetic analyses suggested that four species of Cotesia were always grouped in the same clade regardless of using different analysis methods; Cotesia sp. and C. chilonis are more closely related to each other than to C. ruficrus, different from previous morphological results. Additionally, sequence analyses indicated that NADH1 gene has more parsimony informative characters than 28S rDNA D2 and 16S rDNA at the species-level analysis,indicating that NADH1 gene might be a useful marker for species-level analysis.     

Environmental filtering is the main assembly rule of ground beetles in the forest and its edge but not in the adjacent grassland

In a fragmented landscape,transitional zones between neighboring habitats are common,and our understanding of community organizational forces across such habitats is important.Edge studies are numerous,but the majority of them utilize information on species richness and abundance.Abundance and taxonomic diversity,however,provide little information on the functioning and phylogeny of the co-existing species.Combining the evaluation of their functional and phylogenetic relationships,we aimed to assess whether ground beetle assemblages are deterministically or stochastically structured along grassland-forest gradients.Our results showed different community assembly rules on opposite sides of the forest edge.In the grassland,co-occurring species were functionally and phylogenetically not different from the random null model,indicating a random assembly process.Contrary to this,at the forest edge and the interior,co-occurring species showed functional and phylogenetic clustering,thus environmental filtering was the likely process structuring carabid assemblages.Community assembly in the grassland was considerably affected by asymmetrical species flows (spillover)across the forest edge:more forest species penetrated into the grassland than open-habitat and generalist species entered into the forest.This asymmetrical species flow underlines the importance of the filter function of forest edges.As unfavorable,human-induced changes to the structure,composition and characteristics of forest edges may alter their filter function,edges have to be specifically considered during conservation management.     

CONTAMINATED LEVEL AND RISK ASSESSMENT OF PAES IN THE UPPER REACHES OF THE YANGTZE RIVER北大核心CSCD

PAEs have been proved to be one of the major organic pollutants. The present study determined the level of PAEs using surface water samples from the upper reaches of the Yangtze River. The results showed that DEHP contributed the most to PAEs pollution, followed by DBP. Risk Quotients of PAEs were used for preliminary screening, and DEHP and BBP were identified as potential risk factors with RQ of 310 and 70.7. The MOS10 of DEHP and BBP were 1.40 and 1.32×105, respectively, indicating that BBP may pose little risk to aquatic organisms. The potential risk of DEHP was further analyzed with joint probabilistic curves. Among different biological groups, fish and zoobenthos were two major groups sensitive to DEHP-induced damage under current concentrations with 99.4% and 98.3% for 5% species of each group. While among the toxicity endpoints, reproduction may be more sensitive than others. The 5% and 10% aquatic species were suffered from reproductive damages by 100% and 97.8%, respectively. Overall, our results indicated that DEHP in the surface water of the upper Yangtze River may pose potential risk to aquatic organisms, especially on their reproduction. Therefore, more concerns should be paid in species protection and environmental management. © 2019, Institute of Hydrobiology, Chinese Academy of Sciences. All rights reserved.     

Survival of transplanted nests of the red wood ant Formica aquilonia （Hymenoptera： Formicidae）： The effects of intraspecific competition and forest clear-cutting

The fitness and survival of ant colonies depend on the resources near their nests. These resources may be limited due to poor habitat quality or by intra- and interspecific competitions, which in extreme cases may cause the ant colony to perish. We tested the effect of intraspecific competition and habitat degradation （forest clear-cutting） on colony survival by transplanting 26 nests of the red wood ant （Formica aquilonia Yarrow, 1955） in 26 different forest areas that contained 0-11 conspecific alien nests per hectare. F. aquilonia is highly dependent on canopy-dwelling aphids, thus the removal of trees should cause food limitation. During the course of the 4-year experiment, 9 of the forests were partially clear- cut. We found that while forest clear-cutting significantly decreased the colonies＇ survival, intraspecific competition did not. As a highly polygynous and polydomous species, E aquilonia seems to tolerate the presence of alien conspecific colonies to a certain extent.     

Asymmetric or diffusive co-evolution generates meta-populations in fig-fig wasp mutualisms

Co-evolutionary theory assumes co-adapted characteristics are a positive response to counter those of another species,whereby co-evolved species reach an evolutionarily stable interaction through bilateral adaptation.However,evidence from the fig-fig wasp mutualistic system implies very different co-evolutionary selection mechanisms,due to the inherent conflict among interacted partners.Fig plants appear to have discriminatively enforced fig wasps to evolve"adaptation characteristics"that provide greater benefit to the fig,and fig wasps appear to have diversified their evolutionary strategies in response to discriminative enforcement by figs and competition among different fig wasp species.In what appears to be an asymmetric interaction,the prosperity of cooperative pollinating wasps should inevitably lead to population increases of parasitic individuals,thus resulting in localized extinctions of pollinating wasps.In response,the sanctioning of parasitic wasps by the fig should lead to a reduction in the parasitic wasp population.The meta-populations created by such asymmetric interactions may result in each population of coevolved species chaotically oscillated,temporally or evolutionarily.