Phylogenetic And Geographical Studies On Onychostoma And Parentage Analysis Of Onychostoma Simum

In recent years,with people's increasing attention to environmental problems,the species diversity and genetic diversity of wild freshwater fish in China have also been studied by more and more scholars all around world.Mitochondrial DNA and microsatellite markers,as two molecular markers for studying phylogeny and genetic diversity,are favored by biologists all around the world due to their respective characteristics.So far,due to the climate change and human activities such as overfishing and construction of water conservancy facilities,wild resources of the genus Onychostoma have been greatly damaged.The phylogenetic analysis of the genus Onychostoma,studying their infrageneric relationships and geography pattern,will make a huge difference for the protection of the wild genus Onychostoma.Onychostoma simum is the model species of Onychostoma and Onychostoma simum has short growth cycle,strong fertility and other reasons,which makes them become the main species of artificial breeding and multiplication of discharge.However,germplasm resources are easily degenerating because of inbreeding.So,accurately controling the genetic information of parents and offspring is the prerequisite for ensuring good germplasm and establishing a rational plan of multiplication and release.In this research,the mitochondrial genomes and the Onychostoma of 8 species are the research objects.The basic genetic characteristics,phylogenetic relationships and phylogenetic relationships among the mitochondrial DNAs of the genus were studied.Microsatellite loci screening,Onychostoma simum fish parentage identification methods and genetic diversity of parents and offspring were also discussed.The brief research results are as follows:(1)Onychostoma can be divided into three clades,the Onychostoma rara and Onychostoma alticorpus as a clade,Onychostoma simum and Onychostoma Gerlachi as a clade,the Onychostoma macrolepis,Onychostoma lini,Onychostoma barbatum and Onychostoma barbatulum as a clade;(2)The reasons for the geographical distribution were analyzed through the preliminary estimation of divergence time of the genus.The reason why there was a large geographical discrepancy between the Onychostoma rara and Onychostoma alticorpus was closely related to the geological change;(3)7 polymorphic loci were selected from 21 existing Onychostoma simum microsatellite loci to identify the genetic relationship of 8 Onychostoma simum parents and their 85 offspring.The number of observed alleles in 7 microsatellite loci(N_A)was4-8,the average number of these alleles was 5.280,and the average polymorphic information content(PIC)was 0.683.The results of this experiment showed that all loci polymorphism information content(PIC)>0.5,was highly polymorphic,can provide the exact genetic information.The average heterozygosity of Onychostoma simum,the average expected heterozygosity(H_e)was 0.732 and the average observed heterozygosity(H_o)was 0.724.Among the Heterozygosity of 7 microsatellite loci,except OSI55,were?0.7,Indicating that the these have reached a high degree of polymorphism genetic markers loci.The first parent had a non-exclusionary probability(NE-1P)of 0.568-0.789,a second parent for non-exclusionary probability(NE-2P)of0.390-0.553 and parents for a non-exclusionary probability(NE-PP)of 0.208-0.482.(4)The genetic diversity of the parents and offspring of the Onychostoma simum was compared.The results showed that the information of 7 microsatellite loci in the parental and offspring populations,including the number of alleles,the length of allele fragments,expected heterozygosity(He)and observed heterozygosity(Ho)of each offspring.The number of alleles in the parent population was 4-8 with an average of5.280.The alleles of progeny populations ranged from 4-8 with an average of 5.280.The average expected heterozygosity for the population of parents was 0.771,while the expected heterozygosity for offspring population was 0.731(P>0.05).However,at the same time,the observed heterozygosity of offspring was not significantly lower than that of the parental population of 0.786(P=0.711).(5)The success rate of parental reproduction was analyzed.The results of pedigree identification showed that 16 parents of 4 male and 4 female parents were successfully identified in microsatellite loci of 7 Onychostoma simum.For the male parent,the number of its breeding progeny is 13-31;for the female parent,the number of its breeding progeny is 12-30.In this study,all the Onychostoma simum parents are involved in reproduction,the male offspring of the proportion of 15.4%-36.5%,the female offspring of the proportion of 14.2%-35.4%.