Spatial Distribution And Comparative Analysis For The Wild Myomorphas Of "Three-type" Plague Foci In Yunnan Province

Objective To investigate the community structure and spatial distribution for the wild myomorphas of the “three-type” plague foci and to compare and explore the relationship among the “three-type” foci in Yunnan Province for revealing the characteristic of Yulong plague focus.Methods1.Study sites: Yulong,Jianchuan and Lianghe counties were selected as the investigation areas and the wild myomorphas were collected in different altitude gradients with 2 or 3 samples in forest landscape of each area.Jianchuan was arranged with 3 altitude gradients compared to Yulong and Lianghe with 4 altitude gradients.2.Myomorpha collection: Each plague focus was investigated for 4 times based on the season.The wild myomorphas were collected in the morning with 1 or 2 nights using snap trap on each elevation at least 200 traps and the identification would be done in the laboratory later.3.Data management and analysis: The database of the distribution of the wild myomorphas of each focus and different altitude gradients was dealt with the Excel software 2007 and the Spearman correlation and Fisher Exact test using the SPSS and R software.Results1.A total of 2616 myomorphas were collected by the snap traps in the “three-type”plague foci and the general density was 14.33%,which were divided into 31 species,19 genus,6 families,and 3 orders.In Yulong focus,884 myomorphas were classified into 19 species,12 genus,5 families,and 3 orders.In Jianchuan focus,1069 myomorphas were classified into 17 species,11 genus,5 families,and 3 orders.In Lianghe focus,663 myomorphas were classified into 16 species,11 genus,5 families,and 3 orders.The general density of each area ranked as Jianchuan,Yulong and Lianghe.2.In Yulong focus,Apodemus chevrieri,Apodemus draco,Eothenomys miletus and Apodemus latronum were the dominant species with the constituent ratio of34.95%,17.99%,16.06% and 11.76%,respectively.As a whole,in each altitude gradient,Apodemus chevrieri and Eothenomys miletus were acted as dominant species.With the increase of elevation,there was a trend that the number,density,richness and dominance index of the wild myomorphas were increased,while the diversity and evenness indexes presented the opposite result.Compared to the other altitude gradients,the wild myomorphas community in the area,which is 3000 meters above,showed the spatial heterogeneity(I<0.4).Besides,there was Eothenmys proditor and acted as a dominant species.3.In Jianchuan focus,Apodemus chevrieri,Eothenomys miletus and Apodemus draco were the dominant species with the constituent ratio of 45.74%,33.12% and11.60%,respectively.Apodemus chevrieri and Eothenomys miletus were acted as absolutely dominant species in each altitude gradient with the community structure of the wild myomorphas among each altitude was high similar(I>0.79).There was a negative correlation between dominance indexes and diversity and evenness index,richness and diversity had a low performance in the altitude of 2450~2650 meters,however,a high quantity and density.4.In Lianghe focus,Rattus tanezumi,Rattus steini and Mus pahari were the dominant species with the constituent ratio of 30.62%,18.40% and 11.46%respectively.Rattus tanezumi was the only predominant rodent in each altitude with a phenomenon that the kind and the number of the wild rats increased.With the increase of altitude,richness and evenness decreased,whereas the diversity showed a trend of increase.Besides,the dominance and diversity presented a negative correlation.5.In general,the diversity of the wild myomorphas in the commensal rodent plague foci was larger than the wild rodent plague,whereas the richness was the opposite.Therefore,there was part of cross distribution between commensal and wild rodent plague foci,in which,Rattus tanezumi was captured in wild rodent foci.Even though the composition of the wild myomorphas between two wild rodent plague foci was highly similar(I=0.6892)but the variance existed in performance(P=0.0005).Conclusions1.At an altitude of 3000 meters above in Yulong focus,the heterogeneity was obvious from other elevations on the community of the wild myomorphas as well as Eothenmys proditor had an advantage.However,based on the distribution of the wild myomorphas at each elevation,Apodemus chevrieri and Eothenomys miletus were the dominant hosts.2.In Jianchuan focus,the community structure of the wild myomorphas was high similar in each elevation as well as the Apodemus chevrieri and Eothenomys miletus.3.The Rattus tanezumi presented a single dominant at different elevation and the number and the species of the wild rodent with superior position increased with the altitude increased in Lianghe focus.4.As the whole spatial distribution,the diversity of the wild myomorphas in commensal rodent foci was larger than the wild rodent foci,whereas the richness was lower.Comparing the two wild rodent foci,Yulong had an advantage on both richness and diversity.In the “three-type” foci,part of the wild myomorphas had a cross distribution,which characterized by the Rattus tanezumi was captured in each area,may predict the wild myomorphas in commensal rodent foci might be inherited from the wild rodent foci.5.The community structure of Yulong and Jianchuan wild rodent foci were high similar and had a performance that the dominant wild myomorphas were Apodemus chevrieri and Eothenomys miletus in each foci,so the “two-type” could be considered as one type of plague foci at present.