| The genus,Ceracris Walker,1870 belongs to the family Arcypteridae of superfamily Acridoidea within the order Orthoptera.Up to now 17 species(and subspecies)were recorded in this genus,among of them,15 species(and subspecies)were found in China.It mainly distributed in the south of Qinling-Huaihe region.Therefore,most of studies on the genus Ceracris,,including morphological classifications and phylogenetic relationship were reported in China.In addition,its wide distribution and diversification have attracted more and more attention.In this study,the morphological diversification and shape variation within this genus was explored through the quantitative comparative analyses,in the process of choosing the important taxonomical characteristics and implementing in the geometric morphometric method.Besides,the resultant comparation between the cluster analyses based on the morphological data and the phylogenetic analyses based on the molecular data was discuss in this study.Furthermore,the taxonomic status of species C.nigricornis-nigricornis and C.nigricornis laeta were investigated by integrating the geometric morphometrics method and SLAF-seq technology.The major results of this study were as follows:1.Seven species(and subspecies)of the genus Ceracris can be divided into three group according to the length of body length and hind femur,and the centroid size of wings.The first group was formed by C kiangsu and C.nigricornis laeta are the same type,and the second was formed by C.hoffmanni,C.fasciata fasciata and C.nigricornis nigricornis.The remaining species,C fasciata szemaoensis and C.xizangensis xizangensis constitute the third.The result showed the significant difference on the shape of forewing and hindwing among species(and subspecies).The shape variations were detected mainly at the end of forewing and in media area and jugal vein area of hindwings,respectively.The morphological differentia of the pronotum was covered at the lateral carinae and trailing edge.The species,C.fasciatafasciata and C.fasciata szemaoensis were similar but distinguished from other species on the shape of the pronotum.The similarity was also found among the species,C.nigricornis laela,C.nigricornis nigricornis and C.xizangensis xizangensis.In addition,the variation on the epiphallus was mainly found in the upper edge of the bridge,the anchor projection,and the lophi.2.The result of clustering analysis based on the morphological data showed that the topologies of UPGMA trees constructed by the shape of both forewing and the hindwing ware inconsistent with that of the molecular phylogenetic tree.Moreover,there was a large topological difference between the UPGMA trees constructed from the shape of forewing and the hindwing.However,the cluster results based on the morphology of the pronotum and the epiphallus were supported by molecular data.Furthermore,the close relationship between C.fasciata fasciata and the C fasciata szemaoensis was supported by both morphological analyses based on the shape of the pronotum and the epiphallus and molecular phylogenetic analyses based on the genes of COI and Cytb.Similarly,the close relationship among C.xizangensis xizangensis,C.nigricornis nigricornis,and C.nigricornis laeta was supported by both morphological and molecular evidences.Last but not least,the morphological characters of C.kiangsu,including the shape of hindwing,the pronotum and the epiphallus,are similar to that of C.nigricornis laeta.3.There is no obvious distinction between C.nigricornis nigricornis and C.nigricornis laeta on the length of body and the hind femur.It is hard to distinguished them from the shape of the forewing and the pronotum.One of their morphological differences is the epiphallus,with the relatively straight shape in the lower edged of the bridge in C.nigricornis laeta.In consideration of their less morphological differences,wide distribution and geographical overlap,C.nigricornis nigricornis and C nigricornis laeta should be considered as one species.Their differences on the size of body and wings among the different geographical populations are probably affected by the differences of latitude.The relativity between the size of body and wings and the latitude went against the Bergmann's rule.It showed that the size of body and wings of specimens sampled from the lower latitude was larger than that from the higher latitude.It may resulted by their long-distance flight ability and they could dispersal widely.On the other hand,it is more conducive to their growth and development in the southwestern China,owing to the low latitude,suitable temperature,the humid climate,and the sufficient food resource.However,the shapes of the pronotum and the epiphallus among different geographical populations were more stable and less affected by the environment.4.Based on the genomic SLAF-seq technique,38 individuals from 7 geographical populations of the C.nigricornis nigricornis and the C.nigricornis laeta,and 2 individuals C kiangsu were sequenced.A total of 150.89 M reads were obtained.For those reads,their average Q30 was 93.07%,and the average GC content was 40.77%.A total of 901,598 SLAF tags were characterized by sequence analysis.The average sequencing depth of the tags was 29.42x,and the polymorphic SLAF tags were 228,633,with a total of 2,292,637 SNP markers.The result of phylogenetic analysis showed that individuals of C.nigricornis nigricornis and C.nigricornis laeta were nested.The classification of C.nigricornis nigricornis and C.nigricornis laeta was either not supported by the result of PCA analysis.Thus,population genetic structure was inferred.The result showed that when K=1,the cross-test error rate was the lowest.It indicated that C nigricornis nigricornis and C.nigricornis laeta originated from a single group,which in consist with the molecular result based on mitochondrial DNA.In this study,the results showed that C.nigricornis nigricornis and C.nigricornis laeta have a very similar genetic background and should be treated as one species.5.The results of population genetic differentiation between C.nigricornis nigricornis and C.nigricornis laeta sampled from 7 geographical populations showed that all individuals from the Yunnan(YN)population and Hunan(HN)population formed one clade at the base of the phylogenetic tree,while individuals from the two population were nested.By contrast,all individuals from Shanxi(SX)population grouped together,forming one clade at the tip of the tree.All individuals from Guanxi(GX)population and Anhui(AH)population formed an independent clade,respectively.However,individuals from Hubei(HB)and Sichuan(SC)populations were nested.On the resultant plot of PCA analysis,the 7 geographical populations are clustered into three groups.The first group is the Yunnan population and the second is the Shaanxi population.And the remaining population is the third group.On the resultant graph of population genetic structure,it showed that when K=2,all individuals from the Shaanxi population and all from the Yunnan population were located at the base and the top of the bar chart,separately.It indicated that there is no gene mixture within both of two populations.By contrast,all individuals from the remaining populations were nested and grouped at the middle of the bar chart.It recovered that there was gene mixture among these populations,and the degree of mixing was continuous and regular.Integrating the information from the biogeographical study of genus Ceracris,it inferred that the Yunnan population was relatively ancient,while the Shaanxi population diverged recently.The colonization route of the genus Ceracris in its expansion course started from Yunnan,and then dispersed to Shaanxi through Guangxi,Hunan,Sichuan,Hubei,and Anhui. |
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