Biodiversity And Biogeography Of The Family Cicadidae(Hemiptera:Cicadoidea) From Hainan Island

The family Cicadidae,belonging to Cicadoidea of Hemiptera taxonomically,are widely distributed in the world.Located in the south of China,Hainan Island is a place with very rich biodiversity owing to its tropic environment.However,up to the present,the study concerning diversity and biogeography of cicadas from Hainan Island has received little attention.Also,as a mainland island,Hainan is isolated from the continent by Qiongzhou Strait with only about 25km in width for a long time.Acting as geographical barriers,the Strait as well as mountains on Hainan greatly limit gene exchange among cicada populations distributed both Hainan and Leizhou Peninsula,and their forming effect to cicada population divergence and genetic structure still remains unclear.To solve this problem,we investigate the diversity and distribution of cicada from Hainan based on previous records,and conduct phylogeographical and population genetic structure analyses of their representative Platypleura hilpa Walker 1850 distributed both Hainan and Leizhou Peninsula.Our results are as follows:1.Biodiversity and biogeography of cicadas from HainanA total of 59 species belonging to 28 genera of three subfamilies are examined to comprise Hainan Island cicada fauna.Of these,two new species,Semia hainanenis sp.n.and Nipponosemia hainanenis sp.n.,are described,and 17 species are newly added to this fauna.In particular,Pomponia subtilita Lee and Becquartina bleuzeni Boulard,are also reported for the fauna of China for the first time.In addition,another four species are removed from Hainan Island cicada fauna in the present study.According to their biogeographical information,they have the following distributional characters:(1)There were twelve species having been collected only in Hainan Island,this corresponding to about 20%species endemism.This relative paucity of endemic species might be relevant to less mountain area and lower mountains in altitude on Hainan Island than Taiwan Island.(2)Due to that mountains and rainforest of Hainan are mainly distributed in its south-central region,this environmental heterogeneity make cicadas of Hainan also mainly distribute in this region.Especially,Ledong County have the highest species richness(43 species),and up to 24 species are distributed sporadically and each appearing only in one County or City.(3)Among Zoogeographical Region Divisions of the world,up to 50 species are only distributed in Oriental Region,and 9 species in Oriental Region+Palaearctic Region,one species in Oriental Region+Palaearctic Rregion+Australian Region.Among Zoogeographical Region Divisions of China,The number of common species between Southern China Region and Central China Region are the highest among that between Southern China Region and other Regions,generally reflecting that the number of common species is gradually low as the distance between Southern China Region and other Regions grow.(4)The comparative analysis of common species among Hainan Island and its neighboring cicada fauna revealed that the hybrid area(northern Indochinese Peninsula and adjacent Yunnan and Guangxi Provinces of China)and Hainan share the most common species.2.Phylogeography and population genetic structure of Platypleura hilpa from Hainan Island and Leizhou Peninsula based on mitochondrial COⅠ and COⅡ sequences.(1)The last fragments used to analysis in this study for COⅠ and COⅡ are 588bp and 672bp respectively.35 variable sites are identified from 51 COⅠ sequences,this corresponding to 5.95 percent variability,and only 28 variable sites are examined from 51 COII sequences,this corresponding to 4.17 percent variability.This indicate that evolutionary rate of COⅠ gene is higher than that of COⅡ gene.(2)Based on single COⅠ or COⅡ gene,combined COⅠ+COⅡ genes,the haplotype diversity\nucleotide diversity are 0.94431\0.01812,0.89882\0.01205 and 0.97647\0.01492 respectively.This reveal that Platypleura hilpa from Hainan Island and Leizhou Peninsula has high level of genetic diversity.(3)The phylogenetic trees and median-joining network conducted from 35 haplotypes defined from combined COⅠ+COⅡ sequences have very similar topology.They all show remarkable phylogeographical structure among haplotypes.(4)Based on single COⅠ or COⅡ gene,combined COⅠ+COⅡ genes,we conducted the analysis of population dynamics regarding the 9 populations from Hainan Island as a whole.All the Fu’s Fs values are hightly significant and negative,and the mismatch distributions all show unimodal distributions.This indicate the populations from Hainan have not experienced recent population expansion.(5)AMOVA indicate that a high and significant(P<0.001)proportion(75.62%)of the total variation in the combined COI+COII data are attributable to differences among four geographical regions.All the FST values among four geographical regions are high(FST>0.4)and the Nm values are very low(Nm<1),suggesting that Qiongzhou strait and Wuzhishan and Yinggeling mountain ranges of Hainan are important barriers limiting gene exchange among regions.(6)In spite of high genetic divergence among regions especially between Hainan Island and Leizhou Peninsula,all the populations of Platypleura hilpa have very similar external morphological characteristics.Therefore,an integrated approach including acoustic behavior,habitat preference,etc.is urgently needed to examine whether the reproductive isolation happened among these populations or not.