Metacommunity Structure of Stream Insects across Three Hierarchical Spatial scales

A major challenge in community ecology is to understand the underlying factors driving metacommunity (i.e., a set of local communities connected through species dispersal) dynamics. However, little is known about the effects of varying spatial scale on the relative importance of environmental and spatial (i.e., dispersal related) factors in shaping metacommunities and on the relevance of different dispersal pathways. Using a hierarchy of insect metacommunities at three spatial scales (a small, within-stream scale, intermediate, among-stream scale, and large, among-sub-basin scale), we assessed whether the relative importance of environmental and spatial factors shaping metacommunity structure varies predictably across spatial scales, and tested how the importance of different dispersal routes vary across spatial scales. We also studied if different dispersal ability groups differ in the balance between environmental and spatial control. Variation partitioning showed that environmental factors relative to spatial factors were more important for community composition at the within-stream scale. In contrast, spatial factors (i.e., eigenvectors from Moran's eigenvector maps) relative to environmental factors were more important at the among-sub-basin scale. These results indicate that environmental filtering is likely to be more important at the smallest scale with highest connectivity, while dispersal limitation seems to be more important at the largest scale with lowest connectivity. Community variation at the among-stream and among-sub-basin scales were strongly explained by geographical and topographical distances, indicating that overland pathways might be the main dispersal route at the larger scales among more isolated sites. The relative effect of environmental and spatial factors on insect communities varied between low and high dispersal ability groups; this variation was inconsistent among three hierarchical scales. In sum, our study indicates that spatial scale, connectivity, and dispersal ability jointly shape stream metacommunities.Peer reviewe

Environmental Factors Override Dispersal-Related Factors in Shaping Diatom and Macroinvertebrate Communities Within Stream Networks in China

Metacommunity theory provides a useful framework to describe the underlying factors (e.g., environmental and dispersal-related factors) influencing community structure. The strength of these factors may vary depending on the properties of the region studied (e.g., environmental heterogeneity and spatial location) and considered biological groups. Here, we examined environmental and dispersal-related controls of stream macroinvertebrates and diatoms in three regions in China using the distance-decay relationship analysis. We performed analyses for the whole stream network and separately for two stream network locations (headwater and downstream sites) to test the network position hypothesis (NPH), which states that the strength of environmental and dispersal-related controls varies between headwater and downstream communities. Community dissimilarities were significantly related to environmental distances, but not geographical distances. These results suggest that communities are structured strongly by environmental filtering, but weakly by dispersal-related factors such as dispersal limitation. More importantly, we found that, at the whole network scale, environmental control was the highest in the regions with highest environmental heterogeneity. Results further showed that the influence of environmental control was strong in both headwaters and downstream sites, whereas spatial control was generally weak in all sites. This suggests a lack of consistent support for the NPH in our studied stream networks. Moreover, we found that local-scale variables relative to basin-scale variables better explained community dissimilarities for diatoms than for macroinvertebrates. This indicates that diatoms and macroinvertebrates responded to environment at different scales. Collectively, these results suggest that the importance of drivers behind the metacommunity assembly varied among regions with different level of environmental heterogeneity and between organism groups, potentially indicating context dependency among stream systems and taxa.Peer reviewe

Author Correction: The disease resistance protein SNC1 represses the biogenesis of microRNAs and phased siRNAs.

The original version of this Article contained an error in the spelling of the author Beixin Mo, which was incorrectly given as Beixing Mo. This has now been corrected in both the PDF and HTML versions of the Article

Stream diatom community assembly processes in islands and continents: a global perspective

[EN] Understanding the roles of deterministic and stochastic processes in community assembly is essential for gaining insights into the biogeographical patterns of biodiversity. However, the way community assembly processes operate is still not fully understood, especially in oceanic islands. In this study, we examine the importance of assembly processes in shaping diatom communities in islands and continents, while also investigating the influence of climate and local water chemistry variables on species distributions. Location Global. Taxon Stream benthic diatoms. Methods We used diatom datasets from five continents and 19 islands and applied beta diversity analyses with a null model approach and hierarchical joint species distribution modelling. To facilitate comparisons with continents, we used continental area equivalents (CAEs), which represent continental subsets with comparable areas and the same number of study sites as their corresponding islands counterparts. Results We found that homogeneous selection (i.e., communities being more similar than the random expectation) was the dominant assembly process within islands whereas stochastic processes tended to be more important within continents. In addition, assembly processes were influenced by study scale and island isolation. Climatic variables showed a greater influence on species distribution than local factors. However, in islands, local environmental variables had a greater impact on the distributions of unique taxa as opposed to non-unique taxa. Main Conclusions We observed that the assembly processes of diatom communities were complex and influenced by a combination of deterministic and stochastic forces, which varied across spatial scales. In islands, there was no universal pattern of assembly processes, given that their influence depends on abiotic conditions such as area, isolation, and environmental heterogeneity. In addition, the sensitivity of species occurring uniquely in islands to local environmental variables suggests that they are perhaps less vulnerable to climatic changes but may be more influenced by changes in local physicochemistrySIFor financial support, the authors thank the Academy of Finland (grant nr. 346812 to JS); the Institut Francais de Finlande; the Embassy of France to Finland; the French Ministry of Education and Higher Education; Finnish Society of Sciences and Letters. J.J. Wang was further supported by the National Natural Science Foundation of China (91851117, 41871048), CAS Key Research Program of Frontier Sciences (QYZDB-SSW-DQC043), and The National Key Research and Development Program of China (2019YFA0607100

Uridylation and adenylation of RNAs

The posttranscriptional addition of nontemplated nucleotides to the 3′ ends of RNA molecules can have a significant impact on their stability and biological function. It has been recently discovered that nontemplated addition of uridine or adenosine to the 3′ ends of RNAs occurs in different organisms ranging from algae to humans, and on different kinds of RNAs, such as histone mRNAs, mRNA fragments, U6 snRNA, mature small RNAs and their precursors etc. These modifications may lead to different outcomes, such as increasing RNA decay, promoting or inhibiting RNA processing, or changing RNA activity. Growing pieces of evidence have revealed that such modifications can be RNA sequence-specific and subjected to temporal or spatial regulation in development. RNA tailing and its outcomes have been associated with human diseases such as cancer. Here, we review recent developments in RNA uridylation and adenylation and discuss the future prospects in this research area

Associations and a new species of the genus Apatidelia (Trichoptera, Apataniidae) from China

Xie, Yue, Wang, Beixin, Sun, Changhai (2017): Associations and a new species of the genus Apatidelia (Trichoptera, Apataniidae) from China. European Journal of Taxonomy 333: 1-20, DOI: https://doi.org/10.5852/ejt.2017.33

Descriptions of larvae of three species of Hydropsyche Pictet 1834 (Trichoptera Hydropsychidae) from China

Ge, Xinyu, Wang, Yinchang, Wang, Beixin, Sun, Changhai (2020): Descriptions of larvae of three species of Hydropsyche Pictet 1834 (Trichoptera Hydropsychidae) from China. Zootaxa 4858 (3): 358-374, DOI: https://doi.org/10.11646/zootaxa.4858.3.

Four New Species of the Genus <i>Eoneureclipsis</i> (Trichoptera: Psychomyiidae) from China Inferred from Morphology and DNA Barcodes

Four new species of the genus Eoneureclipsis Kimmins, 1955 from China are described, illustrated, and diagnosed based on male genitalia: Eoneureclipsis jianfenglingensis sp. nov. from Hainan, E. foraminulatus sp. nov. from Guangxi, E. spinosus sp. nov. from Guangxi and Guangdong, and E. gei sp. nov. from Fujian. A dichotomous key to Chinese adult males of Eoneureclipsis is provided. A distribution map for all Eoneureclipsis species is also presented. The DNA barcodes (partial mtCOI sequences) of E. jianfenglingensis sp. nov., E. gei sp. nov., and E. hainanensis Mey, 2013 have been generated and compared with all existing sequences of Eoneureclipsis species

Four New Species of the Genus Eoneureclipsis (Trichoptera: Psychomyiidae) from China Inferred from Morphology and DNA Barcodes &dagger;

Four new species of the genus Eoneureclipsis Kimmins, 1955 from China are described, illustrated, and diagnosed based on male genitalia: Eoneureclipsis jianfenglingensis sp. nov. from Hainan, E.&nbsp;foraminulatus sp. nov. from Guangxi, E.&nbsp;spinosus sp. nov. from Guangxi and Guangdong, and E. gei sp. nov. from Fujian. A dichotomous key to Chinese adult males of Eoneureclipsis is provided. A distribution map for all Eoneureclipsis species is also presented. The DNA barcodes (partial mtCOI sequences) of E. jianfenglingensis sp. nov., E.&nbsp;gei sp. nov., and E. hainanensis Mey, 2013 have been generated and compared with all existing sequences of Eoneureclipsis species