Research On Origin And Diversity Of Tardigrades In Yunnan Province

Tardigrada is a kind of tiny,bilaterally symmetrical creatures.The length of mature individuals is generally 200–500?m,and the longest can reach 1200?m.Both morphological and molecular evidences indicate that the phylum Tardigrada are closely related to the phylum Arthropod and Onychophora,and they form the Panarthropoda,which are an important branch of the Ecdysozoa.However,the specific phylogenetic relationship between Panarthropoda is still very controversial,which restricts the accurate understanding of the origin and early evolution of the various phyla of Panarthropoda.Panarthropoda have a long evolutionary history,and the earliest fossil records can be traced back to the early Cambrian,including Lobopodia that are closely related to the origin of various groups of Panarthropoda.The Cambrian Chengjiang Biota in the eastern part of Yunnan Province is the oldest fossil-lagerst?tten known so far,containing a large number of exquisitely preserved Cambrian Lobopodia and other Panarthropoda fossils.Therefore,an in-depth understanding of the morphological characteristics,gene sequences and ecological distribution of extant tardigrades,as well as their morphological comparisons with Cambrian Panarthropoda,will help to answer the differences between tardigrades and other pan-arthropods,also will help to understand the phylogenetic relationship and their early evolutionary process.Extant tardigrades are widely distributed globally,ranging from marine to freshwater and terrestrial.Currently,there are more than 1,200 species reported globally.Due to the important phylogenetic position of tardigrades and the ability to tolerate extreme environments,tardigrades are currently a scientific hotspot in the study of Panarthropoda.However,compared with the in-depth study of tardigrades by Western scholars,the research on tardigrades in China has been lagging behind,especially the research on tardigrades in the western region is basically in a blank state.Yunnan Province has a variety of ecosystem types,with huge differences in altitude and topography,and is a hotspot of biodiversity in China.But there are few and controversial researches on tardigrades in Yunnan.Therefore,in order to fully understand the biodiversity and geographical distribution of tardigrades in Yunnan Province,and compare them with the morphological characteristics of Lobopodia in Chengjiang,this thesis carried out a systematic study on the classification and distribution of terrestrial tardigrades in Yunnan Province.Drawing lessons from previous studies,14 sampling points were selected in Yunnan Province,namely Tongqinghai Volcanic Lake,Lion Mountain,Yunshanping,Alpine Botanical Garden,Rainforest Periphery,Xishuangbanna Forest Canopy,Green Stone Forest,Longdong,Lingga Village,and Ajiwu crater,Dawei Mountain,Xidang Village,Yunling Township Canyon,General measures of national forest park.Through the separation,identification and statistics of samples at different sampling points,the following preliminary results were obtained:1.A total of 2456 tardigrade animals were collected from 14 sampling points,which were identified as belonging to 3 classes,5 orders,6 families,21 genera and 41 species.Among them,10 new record species in China are: Viridiscus viridissimus Péterfi,1956;Milnesium pacificum Sugiura,Minato,Matsumoto ? Suzuki,2020;Hypsibius pradellii Bertolani ? Rebecchi,1996;Itaquascon pisoniae Pilato ? Lisi,2009;Mesocrista revelata G?siorek,Stec,Morek,Kaczmarek,Lachowska-Cierlik ? Michalczyk,2016;Platicrista horribilis Kaczmarek ? Michalczyk,2003;Calcarobiotus(Discrepunguis)polygonatus Binda ? Guglielmino,1991;Macrobiotus sapiens Binda ? Pilato,1984;Mesobiotus occultatus Kaczmarek,Zawierucha,Buda,Stec,Gawlak,Michalczyk ?Roszkowska,2018;Mesobiotus philippinicus Mapalo,Stec,Mirano-Bascos ?Michalczyk,2016;The 9 newly recorded species in Yunnan Province are: Claxtonia crebraclava Sun,X.Li ? Feng,2014;Echiniscus semifoveolatus Ito,1993;Echiniscus spinulosus Doyère,1840;Pseudechiniscus asper Abe,Utsugi ? Takeda,1998;Adropion belgicae Richters,1911;Dianea rahmi X.Li ? L.Wang,2006;Isohypsibius marcellinoi Binda ? Pilato,1971;Macrobiotus crenulatus Richters,1904;Macrobiotus polyopus Marcus,1928.No new species have been discovered yet.2.Based on the four diversity indexes,this thesis uses comprehensively to analyze the species diversity of different sampling points.The results of the study show that the Shannon-Wiener index(H),the values of the Simpson dominance index(D)and the Pielou evenness index(J)of each sampling point are similar,indicating that the species diversity in each sampling point and the uniformity of the number of species in the community are similar;the value of the Margalef richness index(d Ma)fluctuates greatly,indicating that the species composition of tardigrades at different sampling points is different,but it is still uncertain whether the difference is significant.3.Analyze the community similarity of tardigrade animals at different sampling points.Among them,the community similarity coefficient between Lingga Village and Lion Mountain is the highest,at a medium similarity level,and the rest of the sampling points are at dissimilar levels.Yunnan is extremely rich in biodiversity,but there is still a lack of detailed records on the species richness,distribution and specific morphological characteristics of tardigrades in Yunnan.This master's thesis systematically investigated terrestrial tardigrade species in different regions of Yunnan Province,collected and described 41 species,including 10 new record species in China and 9 new record species in Yunnan Province.This thesis provides a detailed picture record for the specific morphological characteristics of each species through equipment such as Upright Fluorescence Microscope and Scanning Electron Microscope,providing important evidence for the classification and identification of species,and at the same time,it is conducive to further understanding the morphology of Cambrian Panarthropods.The comparative study of characteristics can help to understand the phylogenetic location and evolution process of Tardigrada.At the same time,this paper initially analyzed the diversity of tardigrade animals at each sampling point and the community similarity of different sampling points,showing the complexity of the distribution of tardigrade species,accumulating zoogeographic information,and helping to develop mitigation.Further research on animals.This paper initially analyzed the diversity of tardigrade animals at each sampling point and the community similarity of different sampling points,showing the complexity of the distribution of tardigrade species,and accumulating zoogeographic information,which is helpful to carry out further research on tardigrade animals.