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Temperature tolerances (including lethal limits) and associated rates of thermal acclimation of fish are critical information in predicting fish responses to global climate changes. In this study, a partial sequence of the heat shock protein 70 gene (HSP70) from the fish species Channa striatus was isolated and characterized. Evolutionary process that led to the diversity of HSP70 specific to vertebrates was also analysed. Results revealed that HSP70 is highly homologous in other fish families. The conservation of the HSP 70 gene among fish families could be driven by forces of natural selection due to climatic change. We exposed C. striatus to heat shock (32 °C) and cold shock (16 °C) respectively, in order to examine the differences of temperatures in influencing the expression patterns of HSP70. We revealed that expression of HSP70 was higher at 32 °C than at 16 °C in most of the organs. Specifically, occurrence of chaperone activity of HSP70 was found at low temperature. Therefore, this fish was postulated that to seems to be able to survive at lower temperature compared to higher temperature indicating there is force of natural selection acting towards this HSP 70 gene. This will demonstrate the effect of global warming towards the fish survivability.

In this study we analyzed sequences of the COI gene to investigate the genetic structure and diversity in four populations of the Giant Malaysian Prawn, Macrobrachium rosenbergii, and to test the effectiveness of cyclical mating as means of securing genetic diversity. Forty-three haplotypes were generated for the parental populations; most of these were unique, with moderate genetic and low nucleotide diversities. However Tajima's neutrality test indicated a significant (p < 0.05) departure of the Negeri Sembilan population from the mutation–drift equilibrium, suggesting that it may be losing genetic variability. To combat this problem we recommend a seasonal fishing ban. The AMOVA test results (5.45%, p < 0.00001), the networking of haplotypes and their phylogenetic tree all revealed clear population structuring between the populations. Genetic or haplotype diversity in the progeny groups had increased indicating that a cyclical mating system could be an effective means of maintaining it. The utilization of unique haplotypes in aquaculture, developing DNA barcodes for broods in genetic improvement programs as well as in evaluating restocking activities is recommended. For a better insight into the differences between and among the populations, further investigations using nuclear markers are required.