Glires Species Composition And Habitat Utilization Pattern In Alpine Meadow Ecosystem

Shiqu County,Sichuan Province located in the eastern margin of the Tibetan Plateau,belongs to alpine meadow ecosystem and faces several ecological problems,including the grassland degradation and the transmission of Echinococcus spp..The Glires distributed in Shiqu County are not only considered to be the intermediate hosts of Echinococcus spp.,but also considered to be the main cause leading to local grassland degradation.In order to reduce the population of the local Glires,management departments have carried out some large-scale poison programs.However,both domestic and foreign researches suggest that the Glires play a key role in the stability of the whole ecosystem of Qinghai Tibet Plateau,such as that they are the main food source for a variety of carnivorous animal,and the burrows they excavated are important habitat for a variety of small birds and amphibians.Because of these important roles in ecosystem,the Glires are called keystone species.In view of the contradiction existing between these opinions,more ecology research about Glires is required to carry out,in order to to understand more about their role in the local ecosystem and provide the basis and help for prevention and control work about Echinococcus spp.and glassland.The species composition and habitat utilization pattern of the Glires which this study focused on is the foundation and premise of this.This study was carried out in Yunbo valley,Shiqu County from July to August in 2014.On the one hand,four trapping plots(50mx50m)was set.The Rodentia captured were measured for their body morphological data and their heads and tissue samples were collected.The heads were made into skull specimens,and the species identification was based on the features on skulls and the analysis of body morphological data.At the same time,the Cytb gene and IRBP gene amplified from the tissue samples were used as the DNA barcode,and the species identification was based on genetic distance calculation,sequence similarity comparison and phylogenetic tree construction.On the other hand,eleven walked transects were set,making a total of more than 14.7 km and containing 1278 sampling points.Combined with the geographic information system,the information of burrows distribution and various habitat factors was collected Methods including generalized additive model,Wilcoxon test and Bonferroni Z test were used to analyze the data in order to explore the relationship between the burrows distribution and various habitat factors.Totally,346 Glires samples were captured,including 135 Ochotona curzoniae,16 Phaiomys leucurus,6 Neodon Irene,44 Microtus limnophilus,144 Lasiopodomys fuscus and 1 Ciretulus longicaudatus.The results of this study suggested that CytB gene and IRBP gene serving as DNA barcode perhaps lack enough resolution to distinguish P.leucurus,N.Irene and L.fuscus.In addition,the hybridization introgression of mitochondria and nuclear between these two species had been observed in this study,and this study suggested it maybe happened recently.On the other hand,this study found that there was significant separation between habitat utilization pattern of O.curzoniae and voles(including P.leucurus,N.Irene,M.limnophilus and L fuscus).The habitat with low vegetation height,moderate vegetation coverage and less high shrub was more used by O.curzoniae;the habitat with high vegetation height,higher or lower vegetation coverage,low slope gradient,less O.curzoniae and less dwarf shrub was more used by voles.The habitat utilization pattern of voles was mainly affected by interspecific competition.The O.curzoniae maybe occupy the dominant position and ostracized voles in the interspecific competition.Combined with the above results,three suggestions were propounded:1)new genetic locus should be screened for species identification among voles taxa in China;2)the possibility that population outbreak of Glires was a result from rangeland degradation not a cause for it should be taken into account during the grassland management,and Glires should be treated as bio-indicator species;3)the possibility that poison O.curzoniae maybe cause the population increase of Rodentia and promote the transmission of Echinococcus spp.should be taken into account during the control work about Echinococcus spp..