Study On The Diversity Of Small And Medium - Sized Soil Animals In Taibai Mountain By DNA Combined Barcode Technique

Correct identification of species is the foundation of all biological research. Morphological-based species identification need experienced taxonomists, and usually requires a lot of time. And phenotypic plasticity and the presence of cryptic species can lead to erroneous identification. The morphological differences at different stages of some species can also lead to incorrect identification. The declining number of taxonomists and limitations of morphological-based species identification suggests that we need a new way to accomplish the identification.In 2003, Hebert et al. proposed the concept of DNA barcoding. The emergence of DNA barcoding has made up for some shortcomings of traditional taxonomy, and has an important help to taxonomic research. However, DNA barcoding can only identify one single organism, and shows its weak side when faced with mixed sample and environmental sample. Mixed sample and environmental sample usually containing a large number of and a broad biological classification range of individuals, separation of these individuals and sequencing of barcode sequences of these individuals will be a great challenge.The emergence and continuous development of next generation sequencing technology has solved the problem that DNA barcoding can only identify one single organism. The sequence of each DNA molecule in DNA sample can be obtained by using next generation sequencing technology. Therefore, we can extract the total DNA of mixed individual organisms, then select appropriate molecular marker and perform PCR amplification, then PCR products are sequenced by using next generation sequencing technology, then the sequences obtained are blasted against appropriate database, and then the taxonomic information contained in mixed sample or environmental sample can be obtained. This method which coupled DNA barcoding with next generation sequencing technology is called DNA metabarcoding.At present, the study on soil animal for central and western regions of China is rare. In this study, soil was sampled in 5 different kinds of habitats (alpine meadow, coniferous forest, deciduous small-leaved forest, deciduous broad-leaved forest and farmland) in and around the Taibai Mountain Nature Reserve in early June 2014. The separation of soil meso-microanimals was using Tullgren funnel. Then soil meso-microanimals obtained was studied by using DNA metabarcoding and 18S rRNA gene and COI gene were used as molecular markers. The purpose of this study is to provide basic data for further study of soil animal diversity pattern and its influence factors in Qinling Mountains, and provide a scientific basis for the monitoring and protection of biodiversity in Qinling Mountains. The main results of this study are as follows:(1) A total of 424 species of soil animal is obtained, belonging to 3 phyla,10 classes,34 orders,201 families and 322 genera. Among them, alpine meadow has 321 species, coniferous forest has 315 species, deciduous small-leaved forest has 314 species, deciduous broad-leaved forest has 339 species, and farmland has 327 species. And a list of taxa that has identified to species level or genus level has made.(2) The changes of habitat have some effect on the soil meso-microanimals community composition. The soil meso-microanimals community composition is different in different habitats, but a lot of species is observed in every habitat, as many as 217 species. And each habitat has very few endemic species, respectively:alpine meadow has 10 species, coniferous forest has 7 species, deciduous small-leaved forest has 7 species, deciduous broad-leaved forest has 13 species, and farmland has 8 species.