Effects Of Habitat Fragmentation On The Species Diversity And Genetic Diversity Of Erythroneurini In Typical Karst Regions1 Of Guizhou1

Erythroneurini belongs to subfamily Typhlocybinae(Hemiptera:Cicadellidae).It mainly occurs in forests and grasslands,and is one of the important components of the ecosystem.Its population dynamics and distribution patterns are easily affected by climate and host plants,and can be used as environmentally sensitive indicator organisms.At present,there are few studies on the relationship between this group and changes in the ecological environment.In this study,three typical karst areas in Guizhou(Shibing Yuntai Mountain Nature Reserve,Bijie Salaxi Demonstration Zone,Zhenfeng-Huajiang Demonstration Zone)with large ecological environment differences were used as the study area.Based on data from satellite imagery,field surveys,molecular sequencing,etc.,the habitat fragmentation degree,species diversity and genetic diversity of the Erythroneurine leafhoppers in the study areas were preliminary explored.Combining with the background of the study areas to understand the main factors affecting habitat fragmentation,and put forward reasonable protection suggestions for species resources.The main results are as follows:1.The degree of habitat fragmentation of Erythroneurini is affected by the degree of rocky desertification,and it is positively correlated with it;and the degree of habitat fragmentation of each plot in the study area is directly affected by the size of the continuity of the habitat,and is negatively related to it.In Shibing Yuntai Mountain Nature Reserve,the habitat fragmentation degree of Erythroneurini is the weakest,and the suitable habitat accounts for 91.06%of the total area;Bijie Salaxi Demonstration Zone is second,with a suitable habitat accounting for 68.05%of the total area,and Zhenfeng-Huajiang Demonstration Zone is the strongest,with a suitable habitat accounting for 35.53%of the total area.The index of habitat fragmentation(PD,FN_1,FN_2,Ni,F,FI₁,FI₂)are all expressed as Shibing<Bijie<Huajiang.2.From May 2019 to October 2019,a total of 7,064 Erythroneurine specimens were collected in the three study areas,belonging to 14 genera and 51 species,of which Empoascanara sipra Dworakowska,1980 is the dominant group,accounting for 91.5%of the total number of individuals.The number of Erythroneurine specimens is Bijie(5245)>Shibing(1580)>Huajiang(239).The order of the number of different levels of the taxa is Shibing(10 genus,25 species)>Bijie(8genus,16 species)>Huajiang(8 genus,14 species).3.The species diversity of Erythroneurine leafhoppers in the study areas and sample plots are affected by habitat fragmentation.The weaker the fragmentation degree,the higher the species diversity.The Erythroneurine species diversity is the highest in Shibing Yuntai Mountain Nature Reserve,and the population distribution is relatively uniform,with an average index of species diversity of 1.0069;Bijie Salaxi Demonstration Zone is second with an average of 0.6550;Zhenfeng-Huajiang Demonstration Zone is the lowest,with an average of 0.4228.4.A pairwise comparison and analysis of the similarity of the group composition of Erythroneurini between the study areas and the sample plots were carried out.The results show that the lower the habitat fragmentation,the richer the community diversity,the higher the similarity with other regions,and vice versa.On the genus level,the similarity of the Erythroneurine leafhoppers genera and species composition between Shibing Yuntai Mountain Nature Reserve and Bijie Salaxi Demonstration Zone is the highest,which is 0.750.The similarity of the community structure between Zhenfeng-Huajiang Demonstration Zone and the other two areas is the same,both are 0.625.On the species level,the similarity of the Erythroneurine Erythroneurine leafhoppers communities between the study areas is lower than that of the genus level.The similarity of the community structure between Shibing and the other two areas is 0.625.The similarity between Huajiang and Bijie is the lowest,with a similarity of 0.333.There are few common species of Erythroneurini.In the Shibing Yuntai Mountain Nature Reserve,the average similarity indexs among the various plots are 0.563 and 0.456 on the genus level and pecies level,respectively.In the Bijie Salaxi Demonstration Zone,the average similarity indexs among the various plots are0.532 and 0.375 on the genus level and pecies level,respectively.In the Zhenfeng-Huajiang Demonstration Zone,the average similarity indexs among the various plots are 0.311 and 0.332 on the genus level and pecies level,respectively.5.In terms of time dynamics,the temperature is relatively high from July to September,and the plants are abundant,there are more individual of Erythroneurine leafhoppers in the three study areas,while May and October are relatively rare.And the species similarity between consecutive months is relatively high.In Shibing Yuntai Mountain Nature Reserve,the number of individuals is the largest in September,June and October are the least,and the number of genera and species are the largest in May and October.There is little difference between six months.In Bijie Salaxi Demonstration Zone,the number of individuals and species of Erythroneurine leafhoppers are the highest in August and the lowest in May.In Zhenfeng-Huajiang Demonstration Zone,the number of individuals and species of Erythroneurine leafhoppers are highest in July and lowest in June.6.Analyze the genetic diversity of Empoascanara sipra Dworakowska,1980 in different study areas by mitochondrial Cytb(559 bp),16S r RNA(485 bp)and COI(714 bp)gene sequences.The results show that there are certain genetic differences between different fragmented populations.Among them,the degree of habitat fragmentation in Shibing Yuntai Mountain Nature Reserve is the weakest,the Erythroneurine population has the richest genetic diversity,and the values of each nucleotide polymorphism parameter are the highest.Bijie Salaxi Demonstration Zone is the second.Zhenfeng-Huajiang Demonstration Zone has the most serious habitat fragmentation and the lowest genetic diversity.7.Based on the mitochondrial COI gene sequences of Seriana bacilla Tan,Yuan&Song,2020(662 bp),Empoascanara sipra Dworakowska,1980(714 bp),and Elbelus tripunctatus Mahmood,1967(714 bp),the nucleotide polymorphisms of different fragmented communities in the study areas were calculated.The results showed that the more severe the fragmentation,the lower the genetic diversity.In Shibing Yuntai Mountain Nature Reserve,the genetic diversity of fragmented communities is higher.8.The gene flow estimates of the fragmented Erythroneurine populations in Shibing Yuntai Mountain Nature Reserve,Bijie Salaxi Demonstration Zone,and Zhenfeng-Huajiang Demonstration Zone show that the average of each gene segment as N_{m SB}(6.0511)>N_{m BJ}(1.9365)>N_{m HJ}(1.4254).This result shows that habitat fragmentation will affect the gene flow between different fragmented populations.The higher the degree of fragmentation,the smaller the gene flow of fragmented populations.At present,N_m value of Shibing Yuntai Mountain Reserve is greater than1,and gene exchanges between species are relatively frequent.However,when N_m is equal to 0 in the other two study areas,it means that there is no gene exchange in the population.The habitat fragmentation has a certain impact on the communication between species,and the communication between fragmented populations has been blocked to a certain extent.9.The gene flow among the fragmented communities of Erythroneurini was estimated,and it was found that the gene flow(N_m)among the fragmented communities in the three regions tended to 0,with an average of N_{m SB}(0.0028)>N_{m BJ}(0.0026)>N_{m HJ}(0.0005).This shows that although there is gene exchange between fragmented communities,it is very weak.In Shibing Yuntai Mountain Nature Reserve,the exchange between different species is the highest compared to the other two severely fragmented areas,and the gene exchange in the Zhenfeng-Huajiang demonstration Zone is the lowest.10.In order to better protect the species diversity and genetic diversity of other organisms such as the Erythroneurine leafhoppers species and their host plants,the following measures can be taken based on the background of the study area.(1)Strengthen the control of rocky desertification;(2)Enhance farmers'awareness of ecological protection;(3)Increase the continuity of suitable habitats;(4)Improve the stability of the ecosystem;(5)Improve management policies for protected areas.