Genetic Variation Analysis Of Six Common Carp Populations In China

Aimed to understand the genetic situation of common carp(Cyprinus carpio) populations in China, and the genetic differences between different populationgs of common carp, and help to lay the foundation for breeding programs of common carp. This paper selects four representative wild populations and two selective breeding populations of common carp as the research object, and the Qingshui River Common carp population was the main research target among of them. Genetic diversity and genetic variation of six common carp populations were analyzed by microsatellite marker and D-loop sequence variation. The main results of this paper are as follows:1. Genetic variation analysis of six common carppopulations in China based on D-loop sequencesSix common carp populations, including four wild populations(TH, QSJ, HLJ, HH) and two breeding populations(FRL, SPL) in China, were genetically analyzed with the mtDNA D-loop sequences. A total of 36 variable sites and 27 haplotypes were detected in 185 individuals. QSJ and TH populations had more haplotypes(18 and 9, respectively) than the other populations. Both FRL and SPL populations had one dominant haplotype, with an occupancy of 93% and 80%, respectively. There were highly significant differences(P<0.01)detected among populations, except between SPL and HLJ populations. The pairwise population K2 P genetic distances were ranged from 0.005 to 0.013, and the NJ tree based on genetic distances, showed that FRL and HH clustered together firstly and then clustered with other populations. The analysis of molecular variance(AMOVA) indicated that the percent of variance among populations was 35.59%. Only the FRL population had a significant population amplification phenomenon(P<0.05) estimated through the Tajima’s neutral detection. All the results revealed that QSJ and TH populations had high genetic diversity, which indicated the great genetic inmprovement potency on breeding program in the future. Moreover, both the two breeding populations(FRL and SPL) had high genetic purity, and FRL population displayed an amplification phenomenon in the promoted process.2. Genetic diversity and population structure of six common carp populations in China using microsatellite markersWe genotyped 185 individuals collected from six different common carp populations using 14 polymorphic microsatellites. A total of 374 alleles were detected at 14 loci across the six populations. Breeding populations showed lower allelic numbers and genetic diversities(Na=3.77-7.14 alleles/locus, Ho=0.457-0.725 and He=0.498-0.76 3, respectively) than wild populations(Na=12.00-20.07 alleles/locus, Ho=0.759-0.814 and He=0.835-0.912, respectively). The wild population from QSJ showed the highest polymorphic information content(PIC=0.889) and Shannon’s Information index(I=2.65), whereas SPL, a breeding population, had the lowest genetic diversity parameters(PIC=0.397, I=0.88). The analysis of molecular variance(AMOVA) indicated that the percent of variance among populations and within populations were 8.51 and 91.49, respectively. Pair-wise population differentiations were assessed displayed with significant differentiations(P<0.01). Genetic distances and pairwise FST analysis showed that the largest distance was between wild and breeding common carp populations. Besides, breeding populations had relatively simple genetic structure than wild populations. Population Bottlenecks analysis indicated that QSJ, TH, HHL and FRL populations were deviated from mutation drift equilibrium significantly, and may be experienced a genetic bottleneck recently, so it is necessary to practice the protection for them.3. Morphologic variance and genetic diversity analysis of Qingshui River Common carp based on microsatellite markersThe polymorphism of of 192 common carp individuals catched from Qingshui River were analyzed with morphologic traits and microsatellite molecular markers There was a significant difference among individuals detected through morphological analysis, and body weight has the maximum variation coefficient(38%). Under the genetic analysis using 12 microsatellite loci, results showed that the number of alleles per locus ranged from 5 to 21. The mean observed heterozygosity was 0.54 while the mean expected heterozygosity was 0.86. The mean polymorphism information content(PIC) was 0.84(varying from 0.68 to 0.93). The 192 individuals were divided into three subsets(Subset1, Subset2, Subset3) according to the genetic clusters under genetic structure analysis Subset1 showed significant difference with Subset2 on the number of dorsal fin hard spines and lateral line scale and scale above lateral line(P<0.05), respectively, while showed significant difference(P<0.05) with Subset3 on the ratio between caudal peduncle length and body length. Euclidean distance cluster and discriminant analysis indicated that Subset2 and Subset3 had more similar body characteristics. Furthermore, there were existed significant genetic differetiations among three Subsets. These results mean that Qingshui River common carp has a high level of genetic diversity, the results provide the theoretical basis for the selective breeding of this populations.