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Comparing the functional gene composition of soils at opposite extremes of environmental gradients may allow testing of hypotheses about community and ecosystem function. Here, we were interested in comparing how tropical microbial ecosystems differ from those of polar climates. We sampled several sites in the equatorial rainforest of Malaysia and Brunei, and the high Arctic of Svalbard, Canada, and Greenland, comparing the composition and the functional attributes of soil biota between the two extremes of latitude, using shotgun metagenomic Illumina HiSeq2000 sequencing. Based upon "classical" views of how tropical and higher latitude ecosystems differ, we made a series of predictions as to how various gene function categories would differ in relative abundance between tropical and polar environments. Results showed that in some respects our predictions were correct: the polar samples had higher relative abundance of dormancy related genes, and lower relative abundance of genes associated with respiration, and with metabolism of aromatic compounds. The network complexity of the Arctic was also lower than the tropics. However, in various other respects, the pattern was not as predicted; there were no differences in relative abundance of stress response genes or in genes associated with secondary metabolism. Conversely, CRISPR genes, phage-related genes, and virulence disease and defense genes, were unexpectedly more abundant in the Arctic, suggesting more intense biotic interaction. Also, eukaryote diversity and bacterial diversity were higher in the Arctic of Svalbard compared to tropical Brunei, which is consistent with what may expected from amplicon studies in terms of the higher pH of the Svalbard soil. Our results in some respects confirm expectations of how tropical versus polar nature may differ, and in other respects challenge them. [ABSTRACT FROM AUTHOR]

Our knowledge of the spatial distribution of bryophyte diversity still suffers from low sampling efforts. Here we try to determine the spatial diversity patterns of liverworts and mosses and their environmental drivers more accurately by correcting for this sampling bias. We compiled bryoflora from 49 localities in eastern China, including data on sampling effort. Both sampling bias uncorrected (raw) species richness and bias corrected (estimated) species richness, as derived from species-sampling curves, were used as response variables. Model selection based on Akaike's information criterion was used to evaluate the impact of collection bias on the selection of environmental and spatial variables in the regression models. Variation partitioning was used to assess the independent and joint effects of environmental, spatial and sampling variables on raw and estimated species richness. Liverwort richness increased significantly with decreasing latitude, while moss richness showed no latitudinal pattern, whether for raw or estimated species richness. However, estimated species richness showed stronger correlation with environmental variables than raw species richness. Importantly, selected environmental variables in the raw species richness models changed after correcting for collection bias. Despite their ability to produce copious amounts of spores, our sampling bias corrected models indicated that bryophyte richness showed strong spatial structuring, indicating dispersal limitation. Environmentally, liverwort richness was primarily controlled by water availability, while the richness of mosses was mainly determined by available energy. Our results highlight that biological features, dispersal ability and environmental sorting may account for the discrepancies between species richness of liverworts and mosses. Given the considerable impact that controlling for sampling effort had on analysis outcome, we like to stress the importance of controlling for sampling bias when studying spatial richness patterns in bryophytes. [ABSTRACT FROM AUTHOR]

In forest ecosystems, plant communities shape soil fungal communities through the provisioning of carbon. Although the variation in forest composition with latitude is well established, little is known about how soil fungal communities vary with latitude. We collected soil samples from 17 forests, along a latitudinal transect in western China. Forest types covered included boreal, temperate, subtropical and tropical forests. We used 454 pyrosequencing techniques to analyze the soil communities. These data were correlated with abiotic and biotic variables to determine which factors most strongly influenced fungal community composition. Our results indicated that temperature, latitude, and plant diversity most strongly influence soil fungal community composition. Fungal diversity patterns were unimodal, with temperate forests (mid latitude) exhibiting the greatest diversity. Furthermore, these diversity patterns indicate that fungal diversity was highest in the forest systems with the lowest tree diversity (temperate forests). Different forest systems were dominated by different fungal subgroups, ectomycorrhizal fungi dominated in boreal and temperate forests; endomycorrhizal fungi dominated in the tropical rainforests, and non-mycorrhizal fungi were best represented in subtropical forests. Our results suggest that soil fungal communities are strongly dependent on vegetation type, with fungal diversity displaying an inverse relationship to plant diversity. [ABSTRACT FROM AUTHOR]

Rapidly changing land use in Southeast Asia threatens plant diversity, and reduces the time we have left to document it. Despite over 200 years of scientific plant exploration, many plant species have yet to be discovered. Moreover, we still have a very poor understanding of the distribution of known taxa in this biogeographically complex region. We review the current state of biodiversity exploration, using plants in Indonesia as an example. Traditional methods of collecting and describing species have provided a solid foundation for our understanding of plant biodiversity, but are insufficient for the pragmatic task of rapidly discovering and documenting today's biodiversity before it is gone, because general collecting expeditions tend to be infrequent, and documentation of most new species must await taxonomic revisions many years in the future. Solutions to this exploration and documentation crisis (i) could use the abundant resource of enthusiastic, networked, national biology students, (ii) should employ biodiversity informatics tools to efficiently engage both specialists and parataxonomists, and (iii) might require adoption of new types of a-taxonomy, utilizing increasingly low-cost molecular methods and high resolution photographs. We describe emerging technologies that will facilitate this taxonomic development. We believe that a new golden age of biodiversity exploration may be dawning, just as biodiversity itself is most threatened, and are hopeful that increasing knowledge of biodiversity will be a positive force to slow its loss. [ABSTRACT FROM AUTHOR]

The relative degree to which stochastic and deterministic processes underpin community assembly is a central problem in ecology. Quantifying local-scale phylogenetic and functional beta diversity may shed new light on this problem. We used species distribution, soil, trait and phylogenetic data to quantify whether environmental distance, geographic distance or their combination are the strongest predictors of phylogenetic and functional beta diversity on local scales in a 20-ha tropical seasonal rainforest dynamics plot in southwest China. The patterns of phylogenetic and functional beta diversity were generally consistent. The phylogenetic and functional dissimilarity between subplots (10 × 10 m, 20 × 20 m, 50 × 50 m and 100 × 100 m) was often higher than that expected by chance. The turnover of lineages and species function within habitats was generally slower than that across habitats. Partitioning the variation in phylogenetic and functional beta diversity showed that environmental distance was generally a better predictor of beta diversity than geographic distance thereby lending relatively more support for deterministic environmental filtering over stochastic processes. Overall, our results highlight that deterministic processes play a stronger role than stochastic processes in structuring community composition in this diverse assemblage of tropical trees. [ABSTRACT FROM AUTHOR]