Japan is considered a global hot spot of biodiversity. With regard to species diversity, insects are no exception. To date, more than 32,000 insect species have been identified in Japan, while around 100,000 species of insects are estimated to inhabit this country. In this paper, we outline background factors having contributed to diversification of Japanese insects. Of course, the high degree of Japanese insect diversity is the result of many complex factors. In addition to the humid Asian monsoon climate and the extensive latitudinal gradient of habitats, the extremely complex geological history has contributed as an important factor to generate and maintain the high species diversity and endemism. In particular, the independent origins of northeastern and southwestern Japan from the Eurasian continent have greatly contributed to the diverse composition of Japanese insect fauna. To highlight the importance of this process, we introduce some case studies and previously published papers focusing on several insect groups with low dispersal ability. Those cases indicate that the geological history of Japan has played an important role in the differentiation of Japanese insect species. Besides such geological factors, climatic and ecological factors in combination have contributed to the formation of Japanese insect fauna in complicated ways and produced its particularly high degree of biodiversity. The knowledge compiled here will provide useful information for future studies aiming to understand more deeply the processes of speciation and faunal formation of Japanese insects.
The paraphyletic grouping “Symphyta” (8353 described species) represents the basal lineages of the insect order Hymenoptera. The most species-rich superfamily in Symphyta is Tenthredinoidea (7390 species), with six extant families. Most of tenthredinoids species are phytophagous at the larval stage, and the species using angiosperms as a host are more numerous (6265 species) than those using gymnosperms (140 species) or pteridophytes (985 species). In this study, we investigated whether diversification of Tenthredinoidea could be attributed to their use of angiosperms as hosts by examining host plant usage by lineage. We performed molecular phylogenetic and divergence time estimation analyses using molecular data (~2 kilobase sequence in five DNA regions) and conducted a diversification analysis. Our results suggest that Tenthredinoidea (excluding Blasticotomidae) had used angiosperms since its origin; the phylogeny of Tenthredinoidea showed a significant shift in diversification at two nodes, and those nodes overlap with the periods of origin and diversification of angiosperms.
Selandriinae, a subfamily of family Tenthredinidae (Hymenoptera: Symphyta), comprises multiple tribes, each of which has a relationship with specific plant group. The host specificity of the Selandriinae taxa provides a good model to examine the coevolution between hosts and insects. However, few phylogenetic studies for the Selandriinae obscure the evolutionary scenario with their host‐plants. The present study is a molecular phylogenetic analysis of 19 selandriine species based on mitochondrial genes (12S: 461 sites, 16S: 262sites and COI: 495 sites) and nuclear genes (18S: 773 sites and 28S: 495 sites). The results suggested three of six studied tribes are genetically isolated. Moreover, estimation of the time of molecular divergence showed that the Selandriinae clearly diverged at the same time as their host‐plants (monocots and ferns). These results suggested that the Selandriinae species might have codiversified with their hosts.
The risk of neural disorders associated with cCMV infection is thought likely to increase with CMV viral load in the blood. DBS screening for cCMV may be sufficient in a clinical setting, and offers a realistic and feasible option for universal mass screening.
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