The large yellow croaker (Pseudosciaena crocea Richardson) and the gibel carp (Carassius auratus gibelio) are both commercially important fish species in China. This dissertation consists of two sections. One is the study of the large yellow croaker as following: Firstly Some polymorphic microsatellites from enriched-genomic libraries of the large yellow croaker were isolated using the Fast Isolation by AFLP of Sequences COntaining repeats (FIASCO) protocol and fifteen of them were designed primers and characterized. All of the fifteen microsatellite markers were polymorphism enough for populational genetic research of the large yellow croaker.
Secondly, twelve polymorphic microsatellite loci and four pairs of AFLP selective primers were used to evaluate the genetic variation of one wild-captured and three cultured populations of the large yellow croaker. The results indicate the hatchery operations have lessened the genetic diversity of the large yellow croaker populations in guanjingyang and led to genetic divergence among natural population and cultured populations of the large yellow croaker.
The other part is about the gibel carp. One hundred and nine microsatellites were isolated from gibel carp (Carassius auratus gibelio) by screening through genes found in GenBank, Gibel Carp Gene Database (GCGD) and a genomic DNA library enriched for AG and GATA contructed by using FIASCO protocol. Nineteen microsatellites were usedto identify four clones (A, D, L, F)of the gibel carp and cross-amplification in nineteen crucian carp individuals (Carassius auratus auratus Linnaeus). Twelve microsatellite markers sucessfully identified all the four clones,
two are able to identify some clones but disable to distinguish others and five fail to identify four clones. Intraclonal homogeneity and interclonal heterogeneity were observed in these clones. A phylogenetic tree was constructed using UPGMA cluster analysis based on genetic distance matrix of the four clones (A, D, L, F). The genetic trees indicated clones D and L converge firstly, and then merge with A, finally with F. Except YJ0022, eighteen microsatellites successfully cross-amplified in crucian carp. Fourteen of them were polymorphic (average PIC=0.779, average HE=0.827).
In this study, we identified 108 clones from total 292 gibel carp individuals from six geographical populations by using 12 microsatellite markers. And after comparing the microsatellite patterns among six gibel carp populations and two crucian carp populations, we confined the existance of the natural gibel carp clones and observed the releasing of cultured gibel carp individuals. We suggest that the gibel carp prefer to produce by gonochoristic mechanisms in nature. Additionally, our resultes support the hypothesis that the gibel carps of Heilongjiang river originate from the diploid crucian carp of Jianghan plain area, and we further propose that the gibel carps of Xingjiang also originate from Changjiang water system and different geographical populations of the gibel carps originate from different diploid crucian carp populations.