Geometric Morphometric Studies On DNA Barcoding And Wings In Odontidae

Libellulidae was a larger group of the Anisoptera in Odonata,which were distributed in more than 1,000 species worldwide,including almost all common species.There were 140 species of Libellulidae insects in China,accounting for about 19%of Chinese dragonfly species,involving 34 genera in 11 subfamilies.The majority of species have similar signs and fuzzy morphological descriptions,making identification of dragonfly insects difficult.In this study,COX1 gene based on mtDNA was used as the barcode,and 8 methods were used to conduct simple and rapid species division on the obtained data.The performance and emphasis of several methods in barcode identification were compared,and some species sequences which could not be clearly identified were discussed.As an important morphological feature in species identification,wing was an effective material for distinguishing morphological variation.Compared with other morphological features such as head and genitalia,it was easy to obtain and easy to observe.Based on geometric morphology,this experiment also carried out quantitative analysis on the morphological data of fore-and-hind wings of some species,combined with grid diagram and statistical analysis to discuss the changes in the size and vein of fore-and-hind wings of different species,and attempted to distinguish different species by analyzing the differences between wing types.In this study,the total of 916 coxl gene partial sequences of 645 bp were obtained from 39 species of 16 genera of 6 subfamilies in Libellulidae,combined with the wing-type characteristics of 24 species,the results were obtained as follows:1.The average intraspecific genetic distance of 39 species was 1.6%.Except for the intraspecific genetic distance of Crocothemis servillia and Pantala flovescens,the intraspecific genetic distance of the other species was less than the genetic threshold,and the interspecific genetic and intraspecific genetic distance coincided with the genetic divergence ratio proposed by Hebert(10 times).Most species can be divided at the species level by using coxl gene.The coxl gene also reflects the intraspecific differences in different locations and different numbers,for example,the widely distributed C.ervillia shows great differences among the samples in different locations,which may be hidden species,and there is a higher genetic difference when there are more samples in the same location.2.By analyzing the clustering results of BOLD/ID and NCBI/BLAST,NJ tree,ABGD,jMOTU,GMYC,Genetic software,and TaxonDNA software,it can be known that although the results of barcode analysis methods based on different algorithms are slightly different,there were still Certain applicability.However,Crocothemis servile,which was morphologically identified as a species,was divided into two molecular species in the above methods,and its genetic distance was>3%.Orthetrum pruinosum and Orthetrum testaceum,which were relatively close in morphology,always existed in the form of the same clustering result in the above results,and a small amount of artificial assistance is still needed.Although the Orthetrum lineostigma and Orthetrum brunneum whose genetic distance is less than 3%are classified as an OTU in ABGD and jMOTU methods,they were well divided by other methods.Acisoma panorpoides and Sympetrum parvulum were over divided in GMYC method.3.The analysis of the size of the front and rear wings of 24 species based on geometric morphological measurements shows that although there were certain differences in the size of fore and hind wings of different species(forewings:F(23)=114.155,P<0.001;hindwings:F(23)=102.98,P<0.001),but there was no positive correlation.Such as the Orthetrum glaucum has larger forewings but smaller hindwings than other species,while Trithemis aurosa has larger hindwings but smaller forewings than other species.4.Principal Component Analysis and Thin-plate spline analysis showed that 24 species of dragonfly forewing variants mainly occurred in fin moles(LM3,LM4),anterior midvein and elbow vein areas(LM7 and LM8),and wing nodes(LM12-14),The morphological differences of the hindwings were mainly manifested in the wing tip regions(LM3,LM4)and the gluteal region(LM12-14,LM9)dominated by wing nodes.Analysis of multivariate analysis of wing vein shape(forewings:Wilks lambda=5.745E-12,F=20.22,P<0.001;hindwings:Wilks lambda=5.745E-12,F=12.23,P<0.001)indicate 24 species exsited significant differences;the cross-validation results based on discriminant analysis of front and hind wings showed that the discrimination rate of all species was more than 50%,and most species was up to 100%.