Studies On The Biological Characteristics And Genetic Diversity In Two Bodily Colors Bighead Carps

Random amplified polymorphic DNA (RAPD) technique together with the method ofmorphology, was first applied to study genetic diversity of two bodily colors Bighead carps(Aristichthys nobilis) of Xiangjiang River in the test. Total twenty-three samples, which are tenBlack Bighead carps and thirteen White Bighead carps, were collected for use.The ordinary regulations and T value test were chose to study their morphological features.The results showed notable difference on the caudal fin color, pectoral fin color and body colorof the two stocks. The ratios of head length to eye diameter and head length to interorbitalspace and body length to interorbital space and body length to caudal peduncel length wereextremely remarkable; the difference of the ratio of caudal peduncel length to caudal peduncelheight was obvious. The age of 2~+ and above of Black Bighead carp has a greater growth ratethan that of the White Bighead carp.Of 80 random oligonucleotide primers for amplification of Aristichthys nobilis genomeDNA, 25 could produce distinctive and reproducible fingerprints varying in length from 95 to2359 bp. Each primer used for the detection could produce 1-18 molecular markers. Totally twohundreds and sixty-five sites were detected. There were 80 polymorphic sites (33.90%) of thetotall 236 RAPD sites amplified on Black Bighead. Two hundreds and fifty-seven sites weredetected on White Bighead carp, of which 96 were polymorphic (38.13%).The average similarity index of the two stocks was 0.8712, and the genetic distance was0.1379. Also, the average similarity indexes between individuals of the Black Bighead carpswas 0.9150 ,the average genetic distance was 0.0887 ,and the value of average heterozygositywas 0.085. While the average similarity indexes, genetic distance and heterozygosity were0.9213, 0.0819 and 0.0787 on the White Bighead carp separately. The result illustrated thatthere were low polymorphism between the two bodily colors stocks of bighead carp .Lacking ofgenetic diversity challenged the existence of Bighead carp on the decline in resources.Obvious difference bands can be detected between the two stocks from threeelectrophoresis amplified by S7, S26 and S28, were recorded B-S7-537bp, W-S7-608bp,W-S7-1523bp, W-S7-1682bp, W-S26-324bp, W-S26-283bp, W-S26-224bp, W-S26-175bpand W-S28-365bp. The cluster analysis of the total twenty-three samples was performed with MEGA 3.0 program and NJ method. The results showed relationship of the two stocks. Theindividuals of the White Bighead carp clustered together before the other ones did. It'sestimated that the White Bighead carp stock was a special embranchment of the Aristichthysnobilis.This experiment provides the gists on the molecular level for studying and protection ofBighead carp.