Reduced genetic variation of the Red Sea fish, Randall's threadfin bream Nemipterus randalli, invasive in the Mediterranean Sea

Randall's threadfin bream (Nemipterus randalli) is a Red Sea species that has successfully invaded the Mediterranean via the Suez Canal (Lessepsian migrant). It has established a large population in its new region, shortly after arriving to the Mediterranean. In the present study, the mitochondrial DNA D-loop (control region) of Red Sea specimens of N. randalli was compared to that of specimens from the Mediterranean. A pronounced decrease in genetic variability was observed in the Mediterranean fish, indicating a bottleneck effect. Ten different haplotypes were found among 14 Red Sea specimens, while only six haplotypes were found among 42 Mediterranean specimens. The Simpson's Index of Diversity was significantly larger for the Red Sea than for the Mediterranean fish. In addition, the average genetic distance between any pair of individuals was significantly lower in the Mediterranean samples (4.526 x 10(-3)) than that of the Red Sea samples (6.239 x 10(-3)). It can be concluded that the decrease in genetic variability did not hinder the success of the Lessepsian migrant Nemipterus randalli settlement in the eastern Mediterranean.