Isolation Of Microsatellite Markers And Analysis Of Population Genetics In Cherax Quadricarinatus

The redclaw crayfish Cherax quadricarinatus accounts for the entire commercial production of freshwater crayfish in Australia. Two forms have been recognised, an 'Eastern' form in northern Queensland and a'Western' form in the Northern Territory and far northern Western Australia, To date only the Eastern form that has been exported overseas for culture (including to China).Microsatellite DNA is a widely used molecular marker. The success rate of isolating microsatellite loci from a specified species is getting higher and higher as a result of the advance of related technology. In this study we isolated 48 microsatellite loci from Cherax quadricarinatus by using three genomic enriched librarys, and tested the polymorphism on a population. The screening results showed that seven loci were monomorphic. The remaining forty-one microsatellite loci displayed high levels of polymorphism. A total of 157 alleles was tested with 3.8 per locus (ranging from 2 to 10). The observed (Ho) and expected heterozygosities (HE) ranged from 0.1724 to 0.9846 and 0.3405 to 0.8687, respectively. Two microsatellite loci (CQ24 and CQ32) revealed significant deviations from Hardy-Weinberg equilibrium after Bonferroni correction for multiple tests (adjusted a= 0.0012, k= 41). In addition,18 microsatellite markers of C. quadricarinatus were tested for potential cross-amplification in related species, providing more molecular markers on studying population genetics in closely related species.The genetic structure of three Chinese redclaw crayfish culture liness from three different geographical locations in China (Xiamen in Fujian Province, Guangzhou in Guangdong Province, and Chongming in Shanghai) were investigated for their levels and patterns of genetic diversity using microsatellite markers. Twenty-eight SSR markers were selected and used to analyze genetic diversity levels in three redclaw crayfish culture lines in China. This study set out to improve current understanding of the molecular genetic characteristics of imported strains of redclaw crayfish reared in China. Results indicate that the sampled culture breeds in China have retained considerable amounts of genetic diversity relative to that reported for wild populations in Australia although levels have declined. The highest estimate of divergence was evident between the Xiamen and Guangzhou populations.