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Ecotourist trail-use affects the taxonomic, functional and phylogenetic diversity of mammals in a protected area: lessons for conservation management
No full textEcotourism, by definition, aims to engage peoples' interest in wildlife and the environment. The use of tourist roads and trails to access sites within protected areas (PAs) can detrimentally affect the behavior and distribution of species. The way mammals respond to anthropogenic pressures may differ across taxonomic, functional, and phylogenetic groups; nevertheless, how ecotourist trail-use affects these different diversity remains under-investigated. Here, we assessed 6 metrics of taxonomic, phylogenetic, and functional diversity for a mammal community in a PA in central China, recording how Trail use (using Trail type as a proxy) and habitat variables affected sightings and signs of mammals across 60 replicate 0.5 km transects. We then examined how Trail use affected the taxonomic, functional, and phylogenetic diversity indices of species (>1 kg). Using generalized liner mixed modeling, we identified that more used trail types had a greater adverse effect on all diversity richness indices than did less used trail types. Consequently, tourist pressure was associated with a general tendency to homogenize the site's mammal community. In contrast, the effects of Trail Types on all diversity evenness indices were non-significant. Furthermore, more developed and more heavily used trail types had a greater, significant negative effect on taxonomic, functional, and phylogenetic richness, whereas these richness indices were unaffected by minor trail types, used less intensively. As a general principle, lower biodiversity indices reduce ecosystem resilience, and so it is vital to better understand these responses to balance public access against biodiversity management in PAs
Impacts of methyl jasmonate on Selaginella martensii: volatiles, transcriptomics, phytohormones, and gas exchange
No full textExposing Selaginella martensiito methyl jasmonate caused profound transcriptomic changes, dose-dependent increases in stress volatile emissions, increased 12-oxo-phytodienoic and jasmonic acid concentrations, and decreased gas exchange rate. Methyl jasmonate (MeJA) induces various defence responses in seed plants, but for early plant lineages, information on the potential of jasmonates to elicit stress signalling and trigger physiological modifications is limited. The spikemoss Selaginella martensii was exposed to a range of MeJA concentrations (0, 10, 25, and 50 mM), and biogenic volatile organic compound (BVOC) emissions, photosynthetic rate (A), and stomatal conductance (g(s)) were continuously measured. In addition, changes in phytohormone concentrations and gene expression were studied. Enhancement of methanol, lipoxygenase pathway volatiles and linalool emissions, and reductions in A and g(s), were MeJA dose-dependent. Before MeJA treatment, the concentration of 12-oxo-phytodienoic acid (OPDA) was 7-fold higher than jasmonic acid (JA). MeJA treatment rapidly increased OPDA and JA concentrations (within 30 min), with the latter more responsive. Some genes involved in BVOC biosynthesis and OPDA-specific response were up-regulated at 30 min after MeJA spraying, whereas those in the JA signalling pathway were not affected. Although JA was synthesized in S. martensii, OPDA was prioritized as a signalling molecule upon MeJA application. MeJA inhibited primary and enhanced secondary metabolism; we propose that fast-emitted linalool could serve as a marker of elicitation of stress-induced metabolism in lycophytes
Plant communitymediated methane uptake in response to increasing nitrogen addition level in a saline-alkaline grassland by rhizospheric effects
No full textMethane (CH4) uptake in dryland ecosystems is a pathway in mitigating atmospheric CH4 concentrations. A number of studies have demonstrated that nitrogen availability is a key regulator of the CH4 oxidation process. However, how plants mediate soil CH4 oxidation in response to N addition, particularly in saline-alkaline grasslands in the vast regions of the northern China, has received little attention. We conducted a 3-yr (2017-2019) in-situ experiment with eight N addition levels to examine the effect of N on soil CH4 oxidation, and to explore the linkages between the N-induced changes of plant community and the seasonal dynamics of CH4 in a saline-alkaline grassland. We found that the saline-alkaline grassland was a weak CH4 sink displaying nonlinear CH4 uptake levels in response to N additions, possibly due to the nonlinear changes in the abundance of key functional genes (pmoA) that were responsible for CH4 oxidation. The changes in plant productivity and diversity that were induced by N additions explained 21 % of the variations in CH4 uptake. The N-induced increase in productivity indirectly enhanced CH4 uptake at N addition rates of <10 g m(-2) yr(-1), while the decrease in biodiversity indirectly inhibited CH4 uptake when N addition exceeded 10 g m(-2) yr(-1). The N-induced changes in the plant community can affect CH4 uptake, mainly through the rhizospheric effects of plants. In conclusion, our findings underscore the importance of rhizosphere when assessing the CH4 uptake in saline-alkaline grassland ecosystems
Challenges and solutions to biodiversity conservation in arid lands
No full textThe strategic goals of the United Nations and the Aichi Targets for biodiversity conservation have not been met. In-stead, biodiversity has continued to rapidly decrease, especially in developing countries. Setting a new global biodiver-sity framework requires clarifying future priorities and strategies to bridge challenges and provide representative solutions. Hyper-arid, arid, and semi-arid lands (herein, arid lands) form about one third of the Earth's terrestrial surface. Arid lands contain unique biological and cultural diversity, and biodiversity loss in arid lands can have a dis-proportionate impact on these ecosystems due to low redundancy and a high risk of trophic cascades. They contain unique biological and cultural diversity and host many endemic species, including wild relatives of key crop plants. Yet exten-sive agriculture, unsustainable use, and global climate change are causing an irrecoverable damage to arid lands, with far-reaching consequences to the species, ground-water resources, ecosystem productivity, and ultimately the commu-nities' dependant on these systems. However, adequate research and effective policies to protect arid land biodiversity and sustainability are lacking because a large proportion of arid areas are in developing countries, and the unique di-versity in these systems is frequently overlooked. Developing new priorities for global arid lands and mechanisms to prevent unsustainable development must become part of public discourse and form the basis for conservation efforts. The current situation demands the combined efforts of researchers, practitioners, policymakers, and local communities to adopt a socio-ecological approach for achieving sustainable development (SDGs) in arid lands. Applying these ini-tiatives globally is imperative to conserve arid lands biodiversity and the critical ecological services they provide for future generations. This perspective provides a framework for conserving biodiversity in arid lands for all stakeholders that will have a tangible impact on sustainable development, nature, and human well-being
GWAS-assisted genomic prediction of cadmium accumulation in maize kernel with machine learning and linear statistical methods
No full textThe production and use of many heavy meal contained materials almost inevitably release cadmium (Cd) into environment, generating Cd pollutants with adverse impacts on food and human health. Developing an effective method for Cd concentration evaluation in food crops could be an effective approach for toxicity prediction and pollution control. Here, we exploited the genotype-to-phenotype relationship of maize kernel Cd accumulation at whole-genome level, and developed genome-wide association study (GWAS) assisted genomic-enabled prediction (GP) models using machine learning and linear statistical methods. In benchmark tests, marker density and training populations were key parameters in determining GP baseline precision. With optimized parameters, three statistical methods, including Bayes A, ridge regression-best linear unbiased prediction (rrBLUP) and random forest (RF), showed the highest prediction accuracy (Bayes A, 0.83; rrBLUP, 0.89; RF, 0.75) with 100 iterations of cross-validation. In field trial, GP models with rrBLUP performed better than Bayes A and RF, with a higher GP accuracy (r(MG)) and lower mean absolute error value. Integrating GP with GWAS can be implemented as an effective strategy for accurate evaluation of Cd concentration, which could provide useful guidelines for accelerating the selection and breeding cycle of low-Cd food crops and addressing the environmental Cd contamination problem
Genome-wide signatures of the geographic expansion and breeding of soybean
No full textSoybean is a leguminous crop that provides oil and protein. Exploring the genomic signatures of soybean evolution is crucial for breeding varieties with improved adaptability to environmental extremes. We analyzed the genome sequences of 2,214 soybeans and proposed a soybean evolutionary route, i.e., the expansion of annual wild soybean (Glycine soja Sieb. & Zucc.) from southern China and its domestication in central China, followed by the expansion and local breeding selection of its landraces (G. max (L.) Merr.). We observed that the genetic introgression in soybean landraces was mostly derived from sympatric rather than allopatric wild populations during the geographic expansion. Soybean expansion and breeding were accompanied by the positive selection of flowering time genes, including GmSPA3c. Our study sheds light on the evolutionary history of soybean and provides valuable genetic resources for its future breeding
Assessing conservation priorities of threatened medicinal plants in China: A new comprehensive phylogenetic scoring system
No full textOver-harvesting, habitat loss and fragmentation, and biological invasions have led to a sharp decline in wild medicinal plants population in China, where they are an essential component of traditional medicine and used widely. The current national list of protected medicinal materials, the State Key-protected Wild Medicinal Species List (SKPWMSL), which has not been revised for 30 years, is in urgent need of an update. This study proposes a new scoring system with seven indicators that set the conservation priorities of threatened medicinal plants. The advantages of our approach include: (i) quantitative methods with high repeatability and comparability; and (ii) consideration of the evolutionary history of medicinal species. After assessing 911 threatened medicinal angiosperms in China, we identified 112 species as key medicinal plants for conservation priority (KMPCP). We suggest promoting the SKPWMSL with KMPCP as a supplement and update. Meanwhile, our scoring system will improve the future setting of conservation priority and can be extended to other countries or regions
A juvenile skull from the early Palaeocene of China extends the appearance of crocodyloids in Asia back by 15-20 million years
No full textThe earliest Crocodylia from Asia have been represented so far only by alligatoroids and planocraniids. Although definitive crocodyloids are not known until the late Eocene, it has been hypothesized that Asiatosuchus-like basal crocodyloids originated in Asia before the late Palaeocene. In this paper, we describe a new fossil crocodyloid from the lower Palaeocene of Qianshan Basin, Anhui Province, China. The skull and lower jaw fragment exhibit several characteristics typical of juvenile crocodylians. They also display a combination of features not seen in any other taxon, warranting the erection of a new species and genus, Qianshanosuchus youngi gen. & sp. nov. Its affinities are tested in phylogenetic analyses based on two recent character matrices of Eusuchia. To assess the effect of juvenile characteristics on the outcome of the phylogenetic analyses, juvenile specimens of extant crocodylian taxa are analysed in the same way, showing that the effect of their ontogenetic stage on their placement in the tree is minimal. Our analyses point to a basal crocodyloid position for Q. youngi. With these findings, the presence of Crocodyloidea in Asia is extended to the early Palaeocene, 15-20 Myr earlier than formerly thought. Furthermore, our results corroborate previous hypotheses of a Palaeocene dispersal route of Asiatosuchus-like crocodyloids from Asia into Europe
Cytosolic disproportionating enzyme2 is essential for pollen germination and pollen tube elongation in rice
No full textCytosolic DISPROPORTIONATING ENZYME2 converts maltose to glucose, providing energy and cellular materials for pollen germination and pollen tube elongation in rice. Degradation of starch accumulated in pollen provides energy and cellular materials for pollen germination and pollen tube elongation. Little is known about the function of cytosolic disproportionating enzyme2 (DPE2) in rice (Oryza sativa). Here, we obtained several DPE2 knockout mutant (dpe2) lines via genomic editing and found that the mutants grew and developed normally but with greatly reduced seed-setting rates. Reciprocal crosses between dpe2 and wild-type plants demonstrated that the mutant was male sterile. In vitro and in vivo examinations revealed that the pollen of the dpe2 mutant developed and matured normally but was defective in germination and elongation. DPE2 deficiency increased maltose content in pollen, whereas it reduced the levels of starch, glucose, fructose, and adenosine triphosphate (ATP). Exogenous supply of glucose or ATP to the germination medium partially rescued the pollen germination defects of dpe2. The expression of cytosolic phosphorylase2 (Pho2) increased significantly in dpe2 pollen. Knockout of Pho2 resulted in a semi-sterile phenotype. We failed to obtain homozygous dpe2 pho2 double mutant lines. Our results demonstrate that maltose catalyzed by DPE2 to glucose is the main energy source for pollen germination and pollen tube elongation, while Pho2 might partially compensate for deficiency of DPE2
The micro-morphological characteristics of Cyrtomium Presl (Dryopteridaceae) from Shandong, China and their taxonomic significance
No full textThe fern genus Cyrtomium is generally recognized as a genus difficult to identify taxonomically. Here, the micro-morphological characteristics of nine species and one cultivar of Cyrtomium from Shandong Province of China were studied using scanning electron microscopy (SEM): C. confertiserratum, C. falcatum, C. fortunei, C. polypterum, C. reflexosquamatum, C. semifertile, C. shandongensis, C. tukusicola, C. yamamotoi and C. yamamotoi var. intermedium. The morphology of the pinna margin, upper and lower epidermis, indusia, shape of pinnae, sori distribution and spore morphology were carefully examined and photographed under SEM. The results showed that the micro-morphological characteristics of the pinna margin, upper and lower epidermis, indusia and spore morphology were stable within species and show significant differences between interspecies. The results provide not only important scientific evidence for the micro-morphological classification and identification of Cyrtomium, but also an important scientific basis for the development and utilization of this genus for medicine use and the protection of germplasm resources