The conservation of genetic diversity in agroecosystems and its underlying mechanism are increasingly concerned since highly intensive modern agriculture is eliminating agro-genetic diversity. The rice-fish co-culture system, which has been practiced for more than a thousand years, is a typical traditional agricultural system in southern China. Here, we present a study on the genetic diversity of local common carp populations in rice-fish co-culture systems using microsatellite analysis.
We investigated carp populations in eight regions of five provinces in the rice growing area in southern China, i.e. Qingtian county (120.28E, 28.45N) and Yongjia county (120.68E, 28.15N) of Zhejiang Province, Quanzhou county (111.06E, 25.96N) and Sanjiang county (109.58E, 25.80N) of the Guangxi Zhuang Autonomous Region, Congjiang county (108.90E, 25.76N) and Taijiang county (108.32E, 26.68N) of Guizhou Province, Wuyishan city (118.03E, 27.77N) of Fujian Province and Chenxi county (110.18E, 28.00N) of Hunan Province. All of these sites have a long history of traditional rice-fish co-culture practice. 607 individuals in total were collected from all of these sites. The tail fin of each individual carp was clipped and preserved in 95% ethanol, genomic DNA was extracted from carp samples using a DNA extraction kit. Microsatellite polymorphism of DNA samples was analyzed by using 20 pairs of microsatellite primers.
Results/Conclusions
The Microsatellite analysis indicated that the genetic diversity of field carp populations was high across the eight regions. The number of alleles (Na) ranged from 6.75 to 18.90, and the expected heterozygosity (He) was between 0.75 and 0.88. Pairwise genetic differentiation (Fst) of field carp populations was between 0.008 and 0.075. The results from analysis of molecular variance (AMOVA) showed that most of the genetic variation (92%) was within populations, with only 8% explained by differences among populations (P = 0.001). The principal coordinate analysis (PCoA) revealed that the eight populations were separated in to three groups, group1 (Qingtian population, Yongjia population and Wuyishan population), group2 (Quanzhou population, Sanjiang population and Chenxi population), group3 (Congjiang population and Taijiang population). The above results indicated that the genetic diversity was maintained at a relatively high level across the traditional rice-fish co-culture systems.