Genetic diversity analysis among offspring stocks of three imported Oxyeleotris populations by microsatellite markers

【Objective】The genetic diversity and genetic structure of offspring stocks of three imported Oxyeleotris populations in Guangdong were analyzed, in order to provide basic data for the management of the parent fish and the sustainable utilization of the Oxyeleotris resources, and to lay the foundation for genetic improvement and new variety breeding of Oxyeleotris.【Method】Microsatellite markers were used to analyze the 90 offspring samples from the imported O.lineolatus populations AZ1 and AZ2(introduced in 2000 and 2005 respectively) and the imported O.marmoratus population in 1986(TG).The genetic parameters, including number of alleles(Na), expected heterozygosity(He), polymorphism information content(PIC) and genetic differentiation coefficient(F_st) of the three populations were calculated by PopGene32, CERVUS 3.0 and Arlequin 3.1 software.The phylogenetic tree was constructed by UPGMA of Mega 7.0 program based on Nei's genetic distance, and the genetic structure was calculated by Structure 2.3 software.【Result】The results showed that a total of 32 alleles were identified in the three populations by using of 12 microsatellite markers.The number of average Na of the offspring samples for AZ1, AZ2 and TG populations were 1.33, 1.92, and 2.33 respectively;average He values were 0.034, 0.180, and 0.214;and average PIC were 0.031, 0.155, and 0.191, respectively.The F_st values ranged from 0.077 to 0.384, the genetic similarity values ranged from 0.926 to 0.950, and the genetic distance(Da) values ranged from 0.052 to 0.077.AMOVA analysis of the genetic variation revealed that only 22.54% of the genetic variation came from the inter-populations, and 77.46% genetic variation was from intra-populations among the three populations.UPGMA phylogenetic analysis based on Nei's genetic distance showed that AZ1 and AZ2 populations first clustered together, and then clustered with TG population.【Conclusion】The results indicate that the genetic diversity of the offspring stocks of three imported Oxyeleotris populations is low, and the inbreeding degree of AZ1 population is the high.It is urgent to carry out genetic improvement of Oxyeleotris as soon as possible and increase the number of parents by imported Oxyeleotris from different sources to increase the genetic diversity of the culture populations and avoid inbreeding decline risks.In addition, the three hybrid populations have not been mixed and hybridized, and can still be used as the foundation population of hybrid breeding.