| In this experiment,the genetic characteristics of red shell color Chinese mitten crab Eriocheir sinensis were studied by microsatellite molecular markers,and the genetic effects of long-term artificial breeding were analyzed based on genetic diversity parameters from a new breeding stock "Guang He No 1.",which were selected in recent 3 generations,and the growth potential and performance of different populations were analyzed by comparing the different breeding populations in the same culturing environment and the same breeding population in different breeding environments.The effects of breeding environment on the growth of Eriocheir sinensis were discussed.The main results are as follows:1.11 pairs of microsatellite primers were used with the software Cervus and PopGen 32 to comparatively analyze 3 populations of Chinese mitten crab(red shell Chinese mitten crab,HK;the normal color crab from the red population,QK;“Guang He No.1”,GH1),total of 120.The results showed that polymorphism information content(PIC)from 10 of 11 pairs of microsatellite primers,except for ES34,were more than 0.5,which meets the requirement of evaluation the genetic characteristics of 3 crab populations.The number of effective alleles(Ne)of them were 3.694 8?3.011 5 ? 2.403 9,respectively;heterozygosity(Ho)of them were 0.659 9,0.606 5 and 0.569 2,respectively;the expected heterozygosity(He)were 0.5478,0.6848 and 0.6478,respectively;the Shannon Wiener index(I)of them were 1.318 5?1.189 5 ?0.924 4,respectively.The He and I of HK was significantly lower than GH1 population(P<0.05).The fixation index(Fis)of HK population was negative.However,positive fixation indexes were observed between GH1 and QK populations,which might result from inbreeding.The Hardy-Weinberg equilibrium deviation indexes were negative in GH1 population with heterozygote deletion at 9 microsatellite location.The longest genetic distance and maximum genetic differentiation coefficient(Fst)(0.479 9/0.113 3),and minimum coefficient of genetic similarity(0.618 9)were found in HK and GH1 population;the shortest genetic distance and minimum Fst(0.277 8/0.061 7),and maximum genetic similarity(0.757 5)were found in QK and GH1 population.GH1 and QK population were merged into one group with UPGMA method,HK population was one group alone.However,the level of genetic diversity of HK population was low due to “Ancestor effect”.Therefore,a further selective breeding should be focused on expanding amount of the breeding populations based on the hybridization technology,which could be an effective way for keeping this valuable breeding resource.2.The three generation of Eriocheir sinensis in 2012,2014 and 2016 was selected and 7 pairs of microsatellite primers were used to detect the genetic diversity of the breeding population of Eriocheir sinensis in recent years.7 pairs of primer PIC were all higher than 0.5.In 2012,2014 and 2016,the genetic diversity index of 3 populations of Chinese mitten crab decreased year by year.The average Na decreased from 8.571 4 to 6.00 0,reduced by about 30%,and the difference between 2012 and 2016 groups was significant(P<0.05);the average Ne decreased from 6.001 5 to 4.493 6,decreased by about 25%,and the difference between 2012 and 2016 groups was significant(P<0.05);the average I decreased from 1.992 4 to 1.558 9,reduced by about 22%,There was a significant difference between the 2012 and 2016 groups(P<0.05),and the average He decreased from 0.845 9 to 0.764 9,reduced by about 9.6%,and the difference between the 2012 and 2016 groups was significant(P<0.05).Beside that,the average average Ho in 2014 was less than 0.187 5 in 2012 and 0.653 5 in 2016,and the difference between the 3 groups was significant(P<0.05).Hardy-Weinberg balance detection(HW)showed that in the 2012 population,only ESC20 and ESB88 two loci deviated from the HW balance;in the 2014 population,only one loci of NE27 deviated from the HW balance;in the 2016 population,the two loci of ES38 and NE49 deviated from the HW balance.3.The morphological characteristics of the red shell color(A),the normal shell color(B)and the "Guang He No.1"(C)were compared by using the indoor tanks and rice field enclosures,and the cluster maps were constructed.The results of growth performance among different populations: the growth parameters of each population raised in the indoor environment indicated that the growth rate of population A was the fastest in the indoor environment,which was far greater than populations B and C.The growth parameters of each population raised in rice field environment indicated that the growth rate of population A and C was better than B in rice field culture.The body width,body length and body weight CV of the population NA in the indoor tanks were far below population NB and NC,it's means the A uniformity was the highest.Under the condition of rice field the uniformity was contrary to indoor culture,A was the lowest.The impact of environment at 60 days on the same group: the growth parameter SGR of A population had no significant difference between the indoor and rice fields,and the environment had no obvious influence on the growth of population A;the SGR of population B was significantly lower than rice field,indicating that the population B was sensitive to the environmental change,and the body width and the body length SGR of the population C in the rice fields condition were both higher than indoor population,but little difference between the two groups,to illustrate the growth performance of population C was easily affected by the environment.Six growth parameters for body width,body length and body weight SGR and CV were used as variable factors for a cluster analyse,and compared with the cluster diagram based on molecular marker.The results showed that the population QK and GH1 gathered together and then gathered together with population HK,the same results were showed with that of molecular markers.However,for rice fields,the clustering of the three groups was confused,which might be the influence of environment on growth leading to the different clustering result. |
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