Background: Karst caves are considered as extreme environments with nutrition deficiency, darkness, and oxygen deprivation, and they are also the sources of biodiversity and metabolic pathways. Microorganisms are usually involved in the formation and maintenance of the cave system through various metabolic activities, and are indicators of changes environment influenced by human. Zhijin cave is a typical Karst cave and attracts tourists in China. However, the bacterial diversity and composition of the Karst cave are still unclear. The present study aims to reveal the bacterial diversity and composition in the cave and the potential impact of tourism activities, and better understand the roles and co-occurrence pattern of the bacterial community in the extreme cave habitats. Results: The bacterial community consisted of the major Proteobacteria, Actinobacteria, and Firmicutes, with Proteobacteria being the predominant phylum in the rock, soil, and stalactite samples. Compositions and specialized bacterial phyla of the bacterial communities were different among different sample types. The highest diversity index was found in the rock samples with a Shannon index of 4.71. Overall, Zhijin cave has relatively lower diversity than that in natural caves. The prediction of function showed that various enzymes, including ribulosebisphosphate carboxylase, 4-hydroxybutyryl-CoA dehydratase, nitrogenase NifH, and Nitrite reductase, involved in carbon and nitrogen cycles were detected in Zhijin cave. Additionally, the modularity indices of all co-occurrence network were greater than 0.40 and the species interactions were complex across different sample types. Cooccurring positive interactions in the bacteria groups in different phyla were also observed. Conclusion: These results uncovered that the oligotrophic Zhijin cave maintains the bacterial communities with the diverse metabolic pathways, interdependent and cooperative coexistence patterns. Moreover, as a hotspot for tourism, the composition and diversity of bacterial community are influenced by tourism activities. These afford new insights for further exploring the adaptation of bacteria to extreme environments and the conservation of cave ecosystem.

Invasive insect wood borers are a threat to global forests and tree-related industries as they can damage trees and spread plant pathogens. Reports of damages by wood borers on plants that were planted overseas may facilitate the identification of potential invaders and speed up risk assessment. However, much of this information remains unavailable to the international plant protection community due to language barriers, lack of digitization, or limited circulation of regional literature. Here, we investigated reports of wood borers on 7 important North American commercial tree species planted in China (Carya illinoinensis, Liquidambar styraciflua, Pinus elliottii, Pinus taeda, Quercus texana, Quercus rubra, and Quercus virginiana) in peer-reviewed as well as “grey” (nonpeer-reviewed) Chinese literature. A total of 60 unique wood borer records were found, yielding reports of 4 orders, 39 genera, and 44 species of insect wood borers. Among Coleoptera, longhorned beetles (Cerambycidae) were the most commonly reported colonizers of North American trees in China. Chinese peer-reviewed reports of pests on alien plants are a valuable tool to survey for potential wood-boring invaders of North America, and wherever North American trees are planted and have the potential to encounter Asian invasive insects. Digitization and dissemination of non-English literature are essential for contemporary risk assessment. On the other hand, the nonpeer reviewed “grey” literature, primarily agency reports and student theses, provided only 5% of the records; many incidental observations were unreliable.

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Spatial shifts in the organisation and pattern of ecological networks may be driven by species composition turnover, changes in species abundance and/or abiotic effects on species interactions. To test the above assumptions, we collected arboreal ants and recorded host tree species from five latitudinal sites in Xishuangbanna, China. We constructed bipartite networks and compared spatial variation in species composition, interactions and stability change. We also analysed the relationship between network structure metrics and network stability. Results showed that ant composition differed significantly among the five sites, primarily determined by weaver ants (Oecophylla smaragdina) and Crematogaster ant species. Dominant tree species included Ficus (32 individuals), Hevea (14 individuals), Castanopsis (11 individuals) and Pittosporopsis (8 individuals). Ant richness was positively correlated with tree richness, suggesting that host trees support ant diversity as a fundamental environment. The ant–tree bipartite networks showed low connectance, high specificity and low niche overlap. Links per species and network node were positively correlated with network stability, whereas connectance, nestedness, specificity and niche overlap were not. Ants and trees formed a nonspecific and sparse bipartite network, and the number of nodes and links per species promoted network stability. Because plant richness was positively related to ant richness, and because arboreal ants feed predominantly on extrafloral nectaries, seeds, insects and honeydew secreted from hemipteran insects, we believe the bottom‐up process plays a central role in determining ant–tree interaction networks.

The gut microbiota is essential for the nutrition, growth, and adaptation of the host. Diestrammena japanica, a scavenger that provides energy to the cave ecosystem, is a keystone species in the karst cave in China. It inhabits every region of the cave, regardless of the amount of light. However, its morphology is dependent on the intensity of light. Whether the gut bacteria reflect its adaptation to the cave environment remains unknown. In this research, D. japanica was collected from the light region, weak light region, and dark region of three karst caves. The gut bacterial features of these individuals, including composition, diversity, potential metabolism function, and the co-occurrence network of their gut microbiota, were investigated based on 16S rRNA gene deep sequencing assay. The residues of amino acids in the ingluvies were also evaluated. In addition, we explored the contribution of gut bacteria to the cave adaptation of D. japanica from three various light zones. Findings showed that gut bacteria were made up of 245 operational taxonomic units (OTUs) from nine phyla, with Firmicutes being the most common phylum. Although the composition and diversity of the gut bacterial community of D. japanica were not significantly different among the three light regions, bacterial groups may serve different functions for D. japanica in differing light strengths. D. japanica has a lower rate of metabolism in cave habitats than in light regions. We infer that the majority of gut bacteria are likely engaged in nutrition and supplied D. japanica with essential amino acids. In addition, gut bacteria may play a role in adapting D. japanica’s body size. Unveiling the features of the gut bacterial community of D. japanica would shed light on exploring the roles of gut bacteria in adapting hosts to karst cave environments.

There is still limited information on how genetic introgression impacts morphological variation and population fitness in long-lived conifer species. Two closely related pine species, Pinus kesiya Royle ex Gordon and Pinus yunnanensis Franch. are widely distributed over Southeast Asia and Yunnan province of China, with a large spatial scale of asymmetric genetic introgression and hybridization, and form a hybrid lineage, P. kesiya var. langbianensis, where their ranges overlap in southeast Yunnan. We compared seed trait variation and germination performance between hybrids and parental species and characterized environmental gradients to investigate the genetic and ecological evolutionary consequences of genetic introgression. We found that seed width (SW) differed significantly among the three pines, and all the seed traits were significantly negatively correlated with latitude and associated with the mean temperatures of the driest and wettest quarters. A higher germination fitness of hybrids was detected at a low temperature, indicating that they had better adaptability to temperature stress than their parental species during the germination process. Our results suggest that environmental factors shape seed phenotypic variation in the pine species and that genetic introgression significantly affects seed germination fitness. Therefore, assisting gene flow in natural forest populations might facilitate their adaptation to climate change.

Microbial symbionts can influence a myriad of insect behavioral and physiological traits. However, how microbial communities may shape or be shaped by insect interactions with plants and neighboring species remains underexplored. The fig-fig wasp mutualism system offers a unique model to study the roles of microbiome in the interactions between the plants and co-habiting insects because a confined fig environment is shared by two fig wasp species, the pollinator wasp (Eupristina altissima and Eupristina verticillata) and the cheater wasp (Eupristina sp1 and Eupristina sp2). Here, we performed whole genome resequencing (WGS) on 48 individual fig wasps (Eupristina spp.) from Yunnan, China, to reveal the phylogenetic relationship and genetic divergence between pollinator and congeneric cheater wasps associated with the Ficus trees. We then extracted metagenomic sequences to explore the compositions, network structures, and functional capabilities of microbial communities associated with these wasps. We found that the cheaters and pollinators from the same fig species are sister species, which are highly genetically divergent. Fig wasps harbor diverse but stable microbial communities. Fig species dominate over the fig wasp genotype in shaping the bacterial and fungal communities. Variation in microbial communities may be partially explained by the filtering effect from fig and phylogeny of fig wasps. It is worth noting that cheaters have similar microbial communities to their sister pollinators, which may allow cheaters to coexist and gain resources from the same fig species. In terms of metabolic capabilities, some bacteria such as Desulfovibrio and Lachnospiraceae are candidates involved in the nutritional uptake of fig wasps. Our results provide novel insights into how microbiome community and metabolic functions may couple with the fig-wasp mutualistic systems.

Network analysis helps reveal the details of community organization by holistically assessing species diversity and the relationships contained therein. In this study, we collected arboreal ants from their host trees at three sites (Nabanhe, Menglun, and Bubeng) in the Xishuangbanna National Nature Reserve. Following computation of species diversity, network metrics, and community metrics, we compared the ant-tree bipartite networks between the three sample sites. Network metrics were evaluated using Z values standardized according to two different null models. Tree species composition differed across the three experimental sites, and the ant communities were correspondingly diverse. Ant and tree species number and 研究报告the tree heterogeneity index (Shannon-Wiener diversity index, Simpson diversity index) were highest in Menglun, and lowest in Bubeng. Extinction slopes showed the same trends as the indices for ant and tree species number and tree heterogeneity, but did not display the same pattern as ant species heterogeneity. Evaluated parameters included: weighted nestedness metrics (WNODF), links per species, specialization, modularity, connectance, extinction slope exponent, and niche overlap. The absolute Z values of these parameters were highest in Menglun and lowest in Bubeng. In conclusion, tree species number and heterogeneity determine the ant-tree network stability, which is measured by extinction slope. WNODF and links per species are positively correlated with community stability. In specialized and modular networks, species populating higher trophic levels experience extinction events in direct correlation with those in lower trophic levels.