| Trilophidia annnudata is a widely distributed and common grasshopper in china,belong to Oedipodidae,Trilophidia.It's often distributed in grassland,farmland and open beach environment of the altitude below 2000 meters.The prediction that variation in intraspecific morphology is related to environmental features has long been of interest to ecologists and evolutionary biologists.The results show:1.The size and shape of grasshopper wings can demonstrate the clinal variation along an environmental gradient.However,the intraspecific variation in wing size and shape in grasshoppers distributed across wider geographic areas are still poorly known,and the relationship between morphological variability and environmental heterogeneity hasn't been widely studied.We explored the relationship between size and shape variation of wings in the grasshopper T.annulata,along an environmental gradient,to attempt to determine what factors drive variation in wing shape under complex geographic conditions.The geometric morphometric method was used to measure the wing shape and size differences of T.annnulata among 39 geographical populations in China.A principle component analysis(PCA)was applied to cluster wing shape differences among populations and identify the major environmental factors contributing to the variation.Regression analysis was used to discriminate between morphological variation and environmental factors.The results show of the forewing size and shape were significantly different while as was hind wing size,but not shape in 39 populations of T.annulata.Among 23 environmental factors,temperature,rainfall,solar radiation and latitude were significantly correlated with the size and shape variation of wings.We found that those with smaller bodies and shorter,blunter forewings were mainly distributed in lower latitudes with higher temperatures and more rainfall in mountainous areas.The bigger bodied grasshoppers with longer forewings with upturned ends were distributed in higher latitudes with lower temperatures and less rainfall in open terrain areas.Intraspecific large-spatial size and shape variations in T.annulata show the clinal morphological variation changes with environmental gradient.Variation in wing morphology apparently follows Bergmann clines with the smaller size mainly distributed in lower latitudes and larger wing size more common at higher latitudes.For T.annulata,smaller wing size corresponded with a hot and humid climate in mountainous areas.This may be due to the rapid metabolic rate and geographical isolation.Grasshoppers with bigger wings were found more commonly in cool and dry conditions on plains which may be explained by slower metabolic rates and frequent genetic exchange among populations.2.The paper used the phylogeographic method to identify the mtDNA sequence difference of 15 geographical populations of T.annulata.The genetic data acquired by determinate the COII(684bp)and ND5(724bp)gene of each geographical populations of T.annulata.Combined gene COII-ND5(1408bp)used to detect the genetic differences among populations,and further to discuss the genetic differentiation and dynamics of populations,and its occurrence and diffusion rules.The results show:a large number of private haplotypes within populations of T.annulata,occupied the 95.77%of the total haplotypes.The haplotype analysis revealed populations with higher haplotype diversity(HD)and sequence diversity of(S)and nucleotide diversity(?)mainly distributed in southern mountainous region of 30 degrees north.The genetic differentiation index(Fst)of the 15 populations ranged from-0.0226 to 0.8675,with an average of 0.3057,and the most of the populations differentiation reached a significant level(P<0.5).The higher average differentiation index include Sanya(SY)population and the population distributed in northern of china,the differentiation index was greater than 0.5.Distributed in southern population of 30 degrees north and the Yunnan Guizhou Plateau populations,genetic differentiation index is relatively small,but also reached significant differentiation level.Gene flow(Nm)was opposite to Fst value,smaller Fst value,which means the larger Nm.The gene flow within populations is smaller in the north than in the south of china,this means the population which distributed in north are independent each other,while the populations distribution in south of 30 degrees north,with bigger the gene flow each other,more exchanges between populations.The 15 geographical populations of T.annulata obtained 71 haplotypes to construct phylogenetic tree by methods of Bayesian(BI),Maximum parsimony(MP)and Maximum likelihood(ML)respectively.The result shows the 71 haplotypes are divided into six clades.The Clade 1 is Sanya(SY)population,and the bootstrap value reached 90%in the above three analyzing methods.Clade 2 are mainly Binchuan(BC)and Nanyang(NY)populations,and the bootstrap value also reached 90%in the analysis of three methods.Clade 3 and Clade4 obtains lower bootstrap value in analysis of BI,ML and MP,this means these clades have lower support.The populations of Clade3 are mainly distributed in south and southwest of China.Due to the frequent exchange among population lead to complex haplotype relationships,so the lower support by bootstrap value in the tree.The Clade 4 have aforementioned same reasons.Clade 4 include populations mainly distributed in northern and central of China,show the barrier effect of the Qinling Mountains mountains on the population exchange is little.The bootstrap value of Clade 5 reached 70%in the analysis of three methods.Clade 5 include Fugu(FG)and Yinchuan(YC)populations,which are mainly distributed in northwestern loess plateau.The Clade 6 have lower bootstrap value in three analyses,it shows that the division of the evolutionary branch is not reliable.From the geographical distribution we know the Clade 6 are mainly Jinghong(JH)and Chang'an(CA)populations,there is no direct linkage among these populations in the region,such occurred are very similar to Clade 2.The 71 haptypes network analysis of 15 geographical groups showed that Clade 1,as island population,separated from other clade earlier supporting by a number of middle vectors.The haplotype quantity of Clade 2 was high.It formed an independent branch in Hap40,and closed to the roots of Clade 3.The haplotype of Clade 3 was more,however,the relationship between haploid types were complex,with multilayer nestification.Clade4 included more haploid type,which has been distributed radially with Shaanxi Foping population(Hap17)and Shandong Penglai,(Hap 45)as the root.It was spreaded out to form a number of branches under the support of Hap 15 center and the midst vector,Clade 5and Hap 45 as root.Clade 6 ranged from Changan group,Jinghong and Binchuan populations,and was supported by multiple intermediate vectors.The population dynamics analysis shows Clade 3 and Clade 5 experienced rapid expansion.Clade 2,Clade4 and Clade6 were not significant in Fu's Fs inspection.It showed that Clade 2,Clade4 and Clade6 were relatively stable.T.annulata pulation differentiation time was about Myr 2.5 years ago of the early quaternary.At that time,Hainan population as a independent population(Clade 1)separated from others affected by the isolated island.Clade2 differentiation with other clade was 1.115 Myr years ago.It is consistent with the phylogenetic tree.Several haploid types in Clade2 were no direct relation in territory.The differentiation period was same among Clade3,Clade4 and other clades,which was about 0.36Myr years ago.The clades were unable to separate effectively,because the population integrated more in the quaternary glaciation and interglacial periods.The differentiation time of Clade 5 and other Clades was Myr 0.053 years ago probably.It showed that the populations of Clade 5 had been formed by spreading to the north.The haplotype network analysis showed that the population of the northwest loess plateau formed by the spreading of the north China plain,for example,Shandong province.Clade 6 differentiation times was from 1.115Myr to 0.731 Myr years ago,which was not an independent clade.It include Jinghong population,Chang 'an populations,and Nanling populations,similar to Clade2.It illustrated that the haploid type was early population,and formed earlier.3.Morphological data and genetic data of T.annulata were constructed by UPGMA.The results showed that the analysis results of the Forewing form were different from the genetic data.In the other words,the partial body changes of T.annulata may not caused by the genetic structure differences.From genetic structure analysis,the population division is effective between the northwest loess plateau and north China,while morphology change rule doesn't support this result.The Sanya population can be completely separated from other geographic group according to the genetic information,while the Hainan island populations are mixed together with the species in southern China basing on morphology.The rule is consistent that the population distribution of the humid regions in south China and southwest China is completely separated from the population in northwest arid and semi-arid area,no matter it is based on morphological information or genetic one.It's consistent with the clinal change pattern in biogeography.The genetic structure of adjacent populations tends to be more similar due to gene flow,while greater genetic difference among populations with the increase of geographical distance. |
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