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Aim We addressed the roles of geohistorical and ecological factors on beta diversity patterns of woody plants in the Japanese archipelago. We scrutinized the contribution of recent diversification in shaping the woody plant diversity of insular areas in East Asia.Location The Japanese archipelago. MethodsThe distribution data of 1030 woody plant species were compiled for 65 localities in the archipelago. First, the relationships between geohistorical (straits, distance and area) and ecological (topographical heterogeneity, minimum temperature and annual precipitation) variables and taxonomic and phylogenetic beta diversity were tested using regression models. Second, geographical patterns of phylogenetic beta diversity were compared with those of taxonomic beta diversity using ordination and randomization tests. These analyses were applied to the woody plants overall and their functional groups defined by life-form (coniferous, deciduous broad-leaved and evergreen broadleaved groups).Results Distance and minimum temperature showed significant positive relationships with both measures of beta diversity across the woody plants overall and the functional groups. The contributions of geographical barriers, topographical heterogeneity and annual precipitation varied among groups. Ordinations by phylogenetic beta diversity produced patterns that were consistent with those generated by taxonomic beta diversity, showing three clusters of localities in relation to geographical barriers, except in the coniferous group. The regression slopes of phylogenetic beta diversity versus distance were significantly smaller than those of taxonomic beta diversity versus distance across all groups.Main conclusions In the Japanese archipelago, the combination of geographical isolation and environmental filtering in response to geohistorical perturbations and environmental gradients has configured the beta diversity patterns of woody plants. The recent diversification of phylogenetically close relatives probably caused the spatial variations that exist in woody plant diversity. The archipelago functions as a refugium for relict taxa and as a hotspot for neoendemics, contributing to the broad-scale diversity bias favouring East Asia.

In psoriasis lesions, a diverse mixture of cytokines is up-regulated that influence each other generating a complex inflammatory situation. Although this is the case, the inhibition of IL-17A alone showed unprecedented clinical results in patients, indicating that IL-17A is a critical inducer of psoriasis pathogenesis. To elucidate IL-17A-driven keratinocyte-intrinsic signaling pathways, we treated monolayers of normal human epidermal keratinocytes in vitro with a mixture of six cytokines (IL-17A, TNF-α, IL-17C, IL-22, IL-36γ and IFN-γ) involved in psoriasis to mimic the inflammatory milieu in psoriasis lesions. Microarray and gene set enrichment analysis revealed that this cytokine mixture induced similar gene expression changes with the previous transcriptome studies using psoriasis lesions. Importantly, we identified a set of IL-17A-regulated genes in keratinocytes, which recapitulate typical psoriasis genes exemplified by DEFB4A, S100A7, IL19 and CSF3, based on the differences in the expression profiles of cells stimulated with six cytokines versus cells stimulated with only five cytokines lacking IL-17A. Furthermore, a specific IL-17A-induced gene, NFKBIZ, which encodes IκB-ζ, a transcriptional regulator for NF-κB, was demonstrated to have a significant role for IL-17A-induced gene expression. Thus, we present novel in vitro data from normal human keratinocytes that would help elucidating the IL-17A-driven keratinocyte activation in psoriasis.

The vertical stratification of lepidopteran and coleopteran communities in a cool-temperate deciduous forest in Japan was examined to evaluate the hypothesis of an expected uniform distribution of mobile flying insects between the canopy and understory of temperate forests. Lepidopteran and coleopteran insects were trapped using light traps at three sites in each of the canopy and understory for three consecutive nights each month from April to October 2001. For Lepidoptera, species richness, abundance, and family richness were significantly higher in the understory than in the canopy. For Coleoptera, only abundance was larger in the canopy relative to the understory; species and family richness did not differ between the strata. The beta diversity of the lepidopteran community was larger between the strata than among sites, but the coleopteran community showed an inverse pattern. These results imply the presence of vertical stratification within the lepidopteran community, but not within the coleopteran community, in the temperate forest. The understory contributes more than the canopy to lepidopteran diversity in the temperate forest, although this stratification may be relatively weak because, in contrast to the situation in tropical forests, the canopy and understory assemblages share many species.

Aim To examine the roles of geohistorical and ecological factors in the development of butterfly assemblages on continental islands with multiple source pools.Location The Ryukyu Islands, Japan. This arc of continental islands is located between two source islands, Kyushu and Taiwan, and contains two major straits, the Tokara and Kerama gaps.Methods A total of 489 butterfly species were identified on 59 islands, including the two source islands. The influences on species richness and rarity of latitude, area, elevation, and distances from the nearest source and from the nearest larger island were analysed using generalized linear models. The relationships between differences in area, elevation, and distance and dissimilarity between island butterfly faunas were evaluated by multiple regressions on distance matrices. The relationships between area, elevation, and distance from the source and dissimilarity to the source fauna were examined using linear models. The dissimilarity was based on the Sørensen index and its nestedness and turnover components.Results Latitude, area and isolation determined species richness and rarity, whereas differences in elevation and distance regulated species turnover between islands. The gaps between islands were associated with nestedness between island faunas. Area consistently had a negative relationship with the total dissimilarity to source fauna. The overall dissimilarity to Kyushu decreased with the distance from Kyushu, whereas dissimilarity to Taiwan increased with distance from Taiwan.Main conclusions Both environmental filtering and dispersal limitation determine the geographical patterns of butterfly assemblages in the Ryukyus. The present study focuses on the unique pattern wherein migration from Kyushu is facilitated on islands farther from Kyushu, while migration from Taiwan is inhibited on islands farther from Taiwan. The two source islands have contrasting roles that affect butterfly distributions unidirectionally. This study highlights the importance of resolving dissimilarity into nestedness and turnover components to elucidate the formation of island biota.