Abstract In order to verify the escape‐from‐enemy hypothesis from the changes of nutrient substance and fitness of natural enemies on alien plants, contents of free amino acids in native and invasive plant populations of Ageratina adenophora and life history parameters of specialist herbivore Procecidochares utilis reared on these plants were investigated. Our results showed that the contents of glycine, valine, γ‐aminobutyric acid, proline, serine, alanine, and arginine in the invasive plants were higher than those in the native plants of A. adenophora . There was a shorter developmental duration and higher fecundity of P. utilis when fed on the invasive plants. The results indicated a possible fitness tradeoff of natural enemies between invasive and native plants arose from nutrient substance changes.
A harmonious society shows that a society system makes all aspects well-organized,coordinated and promoted each other.General social problems are scientifically resolved by the Marxist views of development,which is unification of harmonious,comprehensive and sustainable development views among human,society and nature.A harmonious society stresses the comprehensive,coordinated and sustainable aim,which is also the approach for developing the harmonious society.Comprehensive and sustainable development can not stay in a given phase,but proceed continuously,which is the basic requirements of either developing economic social science or constructing socialistic harmonious society.
Abstract Some research indicates that soil seed banks can promote species coexistence through storage effects. However, the seed bank mechanism that maintains plant assembly and its role in degraded grassland restoration are still not clear. We collected seed bank samples from early, mid and late secondary successional stages of an abandoned subalpine meadow on the Tibetan Plateau, and samples from each stage were exposed to full (i.e., natural), mid, and low light treatments in the field to represent light availability at the bottom/understory (soil surface) of a plant community in the early, mid and late stages of succession, respectively. Species richness, seed density, species composition, and community weighted mean values (CWMs) of seed mass of the species whose seeds germinated in soil samples were evaluated. In response to the light treatments, species richness increased significantly with increased light only for the late successional stage, seed density increased significantly with increased light only in the early and mid successional stages, and seed mass decreased significantly with increased light only in the mid and late successional stages. Species composition differed significantly among the light treatments only in the late successional stage. For the successional series, species richness and seed mass of the species that germinated increased significantly with succession only under mid and full light treatments. Seed density decreased significantly with succession in each light treatment. Species composition differed significantly between the early‐ and late stage and between the mid and late stage in each light treatment. Both the abiotic (light) and biotic (seed mass) factors influence seed bank recruitment to the plant community. Regeneration of small‐seeded species in the seed bank was inhibited under low light in the late successional stage. The balance of stochastic and deterministic processes along a successional gradient was determined by regeneration from the seed bank depending on light intensity change. Differences in seed response to light intensity change largely determined plant community assembly. Our findings should help in the development of effective conservation and restoration strategies.
Informed species delimitation is crucial in diverse biological fields; however, it can be problematic for species complexes. Showing a peripatric distribution pattern, Stewartia gemmata and S. acutisepala (the S. gemmata complex) provide us with an opportunity to study species boundaries among taxa undergoing nascent speciation. Here, we generated genomic data from representative individuals across the natural distribution ranges of the S. gemmata complex using restriction site-associated DNA sequencing (RAD-seq). Based on the DNA sequence of assembled loci containing 41,436 single-nucleotide polymorphisms (SNPs) and invariant sites, the phylogenetic analysis suggested strong monophyly of both the S. gemmata complex and S. acutisepala, and the latter was nested within the former. Among S. gemmata individuals, the one sampled from Mt. Tianmu (Zhejiang) showed the closest evolutionary affinity with S. acutisepala (which is endemic to southern Zhejiang). Estimated from 2996 high-quality SNPs, the genetic divergence between S. gemmata and S. acutisepala was relatively low (an Fst of 0.073 on a per-site basis). Nevertheless, we observed a proportion of genomic regions showing relatively high genetic differentiation on a windowed basis. Up to 1037 genomic bins showed an Fst value greater than 0.25, accounting for 8.31% of the total. After SNPs subject to linkage disequilibrium were pruned, the principal component analysis (PCA) showed that S. acutisepala diverged from S. gemmata along the first and the second PCs to some extent. By applying phylogenomic analysis, the present study determines that S. acutisepala is a variety of S. gemmata and is diverging from S. gemmata, providing empirical insights into the nascent speciation within a species complex.
Weeds detection plays a vital role in weeds removal. To obtain a competitive performance weed detection model, extensive annotated data related to weeds is required which is expensive and time– consuming. Furthermore, it is challenging for model training as weeds are always changing. Data augmentation is one of the methods to make variations in training dataset which can be used in this problem. We propose an Automatic Generative Adversarial Network Augmentation method that combines the advantages of Generative Adversarial Network (GAN) and data augmentation to increase the diversity of weeds morphology and improve the model feature extraction ability of different types of weeds. In addition, we combine the GAN model with the interested areas in images to generate weeds images. We also propose a data augmentation method to automatically add new weeds images into the original one and save the new annotations. We collect pictures of three weed species (Bitter Gentian, Hawk’s Beard, Pedunculate) in natural scenes and label them to build a dataset with clear annotations. We test the efficiency of the proposed Automatic Generative Adversarial Network Augmentation (AGA) method in universal deep learning models and compare it with classical data augmentation methods. The experiments show that the proposed AGA method is superior with the shortest training time and highest accuracy both on our weeds dataset and a public crop-weed dataset which shows strong generalization ability.
Effects of salt stress on photosynthetic characteristics and Chlorophyll Fluorescence Parameters in leaves of three poplar cultivars were studied.The results showed that the contents of chlorophyll a(Chla),b(Chlb) in leaves of three poplar cultivars did not change significantly in the treatments with 100?200?300mM salt solution,but they decreased significantly in the treatment with 400mM salt solution compared with those in the control after 24 days of salt stress;The contents of carotenoid(Car) in leaves of three poplar cultivars did not change significantly from those in the control all through salt-treating process.The gas exchange parameters such as Pn,Tr,Gs declined and the change trend of Ls increased at the beginning then declined while the trend of Ci was reversed.It was stomatal limitation that leading the photosynthesis declined in the treatments with lower concentrations,on the contrary,non-stomatal limitation was the dominative causation in the treatments with higher concentrations.As the concentrations intensified the Chlorophyll Fluorescence Parameters such as Fo?Fm?Fv/Fm?NPQ all declined gradually.The gradation of salt-Tolerance of three poplar cultivars is P.×xiaozhuanica Populus simonii×P.euphratica×P.sp24Populus simonii×P.euphratica×P.sp19.
Reproductive bud differentiation is one of the most critical events for the reproductive success of seed plants. Yet, our understanding of genetic basis remains limited for the development of the reproductive organ of gymnosperms, namely, unisexual strobilus or cone, leaving its regulatory network largely unknown for strobilus bud differentiation. In this study, we analyzed the temporal dynamic landscapes of genes, long non-coding RNAs (lncRNAs), and microRNAs (miRNAs) during the early differentiation of female strobilus buds in Ginkgo biloba based on the whole transcriptome sequencing. Results suggested that the functions of three genes, i.e., Gb_19790 (GbFT), Gb_13989 (GinNdly), and Gb_16301 (AG), were conserved in both angiosperms and gymnosperms at the initial differentiation stage. The expression of genes, lncRNAs, and miRNAs underwent substantial changes from the initial differentiation to the enlargement of ovule stalk primordia. Besides protein-coding genes, 364 lncRNAs and 15 miRNAs were determined to be functional. Moreover, a competing endogenous RNA (ceRNA) network comprising 10,248 lncRNA-miRNA-mRNA pairs was identified, which was highly correlated with the development of ovulate stalk primordia. Using the living fossil ginkgo as the study system, this study not only reveals the expression patterns of genes related to flowering but also provides novel insights into the regulatory networks of lncRNAs and miRNAs, especially the ceRNA network, paving the way for future studies concerning the underlying regulation mechanisms of strobilus bud differentiation.
Cardamine occulta (Brassicaceae) is an octoploid weedy species (2n = 8x = 64) originated in Eastern Asia. It has been introduced to other continents including Europe and considered to be an invasive species. Despite its wide distribution, the polyploid origin of C. occulta remained unexplored. The feasibility of comparative chromosome painting (CCP) in crucifers allowed us to elucidate the origin and genome evolution in Cardamine species. We aimed to investigate the genome structure of C. occulta in comparison with its tetraploid (2n = 4x = 32, C. kokaiensis and C. scutata) and octoploid (2n = 8x = 64, C. dentipetala) relatives.Genomic in situ hybridization (GISH) and large-scale CCP were applied to uncover the parental genomes and chromosome composition of the investigated Cardamine species.All investigated species descended from a common ancestral Cardamine genome (n = 8), structurally resembling the Ancestral Crucifer Karyotype (n = 8), but differentiated by a translocation between chromosomes AK6 and AK8. Allotetraploid C. scutata originated by hybridization between two diploid species, C. parviflora and C. amara (2n = 2x = 16). By contrast, C. kokaiensis has an autotetraploid origin from a parental genome related to C. parviflora. Interestingly, octoploid C. occulta probably originated through hybridization between the tetraploids C. scutata and C. kokaiensis. The octoploid genome of C. dentipetala probably originated from C. scutata via autopolyploidization. Except for five species-specific centromere repositionings and one pericentric inversion post-dating the polyploidization events, the parental subgenomes remained stable in the tetra- and octoploids.Comparative genome structure, origin and evolutionary history was reconstructed in C. occulta and related species. For the first time, whole-genome cytogenomic maps were established for octoploid plants. Post-polyploid evolution in Asian Cardamine polyploids has not been associated with descending dysploidy and intergenomic rearrangements. The combination of different parental (sub)genomes adapted to distinct habitats provides an evolutionary advantage to newly formed polyploids by occupying new ecological niches.
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