Abstract

In the present study, six microsatellite markers, namely, CSCUPmo1, CSCUPmo2, CSCUPmo3, CSCUPmo4, CSCUPmo6 and CSCUPmo7 were used to monitor genetic variation in the wild tiger shrimp, Penaeus monodon (Fabricius). The number of alleles examined by all the microsatellites yielded the monitoring ranges of 2 to 6 alleles. Moreover, the highest and lowest heterozygosity were found to be at a significant level of 0.33 in CSCUPmo1 and at a significant level of 0.47 in CSCUPmo2, respectively. These observations indicated the existence of substantial genetic diversity in P. monodon in Malaysia. None normal 'L' shaped distribution of mode-shift test, significant heterozygote excess on the basis of different models, as revealed from Sign, standardized differences and Wilcoxon sign rank tests as well as significant M ratio value suggested that there was recent bottleneck in the existing population, providing important information for shrimp breeders.

Key words: Genetic bottleneck, Penaeus monodon, microsatellite, heterozygote.