The Genome Size And Evolution Analysis Of 51 Species Of Locusts

[Objective]Genomic size,also known as C value,refers to the DN A content of a complete set of chromosomes in organismal haploid cells,is an important characteristic of species.Genome size variation has been widely studied by biologists.However,due to the lack of systematic data,the mechanism of variation and biological significance of insect genome size have rarely been studied.Orthoptera is the only group with increased genomes size in the Insecta.Its solid taxonomy and phylogenetic research provides a good material for studying the mechanism and biological significance of genome size variation.Acridoidea is the largest and most widely distributed superfamily of Caelifera,some species can cause disasters and economic losses in agriculture and forestry,and has always been the focus of entomologists around the world.The study of genome size of the Acridoidea have important theoretical significance in revealing the evolutionary model and influence factors of genome size of Caelifera.and establish a solid foundation for the research on the genome of Caelifera.[Methods]In this study,Flow cytometry was used to measure the genome size of 51 Acridoidea species with Periplaneta americana,Locusta migratoria and male CB5L7 mouse as internal references.Body length were obtained via measurement or from literature and online information.Genome sizes difference between male and female,as well as inter-individual differencere were analyzed.Based on the existing data,phylogenetic tree of 51 Acridoidea species was reconstructed through Bayesian phylogeny inference.The ancestral state of genome size was inferenced in Mesquite,and the evolutionary characteristics of genome sizes were analyzed by phylogenetic comparative methods in R 3.5.2.Finally,regression analysis was used to explore the correlation between genome size and body length.[Results]The genome sizes of 51 Acridoidea species were examined,including Catantopidae(15 species),Arcypteridae(8 species),Oedipodidae(17 species),Gomphoceridae(I species),Pamphagidae(4 species),Acrididae(3 species),and Pyrgomorphidae(3 species).The range of genome size varied between 6.535pg and 19.855pg,and the average genome size was 11.87pg.The genome size of Catantopidae was more variable than that of other 6 families.The results of genome size comparison between male and female individuals of the same species showed that the temale individuals have larger genome size than male individuals.The ancestral state reconstruction of genome size indicates that for Acridoidea,the common ancestor genome size is approximately 9.s17pg.The phylogenetic analysis of genome size(?=0.991,K=3.265)and body length(?=0.974,(K=0.339)showed that both have strong phylogenetic signals.However,no correlation existed between genome size and body length in the regression analysis.[Conclusions]The genome size of the 51 Acridoidea species indicates that the Acridoidea insects have a large genome size and wide range of variation;the male individual's genome is smaller than the female individual,which may be related to the XO sex determination system in Acridoidea;the result of genome size ancestral state reconstruction showed obvious amplification during the evolutionary process of Acridoidea.The phylogenetic analysis showed that both genome size and body length of Acridoidea have significant phylogenetic signal,but both was not significantly correlation with each other.