English abstract
Genetic assessment of marine organisms like spiny lobster is important for identifying stocks for fishery management. Larvae of marine organisms disperse over long distance which can make stocks highly mixed and fisheries management difficult without accurate stock identification. Spiny lobster fishery in Oman has been declining and studying the genetic diversity of this species will help its management. In this study the genetic structure of spiny lobster (Panulirus homarus) from Al Sharqiyah governorate has been studiedusing forty-nine previously characterized microsatellite markers.
Twenty and thirty samples of P. homarus were taken from Al-Ashkharah and Masirah regions respectively. DNA was extracted using CTAB extraction method. Polymerase Chain Reaction was done for the total microsatellites in the fourteen multiplexes designed. Fragment analysis was done using 3130 capillary sequencer and microsatellites were sized using GeneMapper software. Based on the results of microsatellites fragment analysis, genetic diversity was measured and P. homarus structuring was examined using different software. The microsatellites loci used were polymorphic as indicated by their average Polymorphic Information Content (PIC = 0.505), average number of alleles and allelic richness (6.65 and 6.44 respectively). The average expected and observed heterozygosity were 0.543 and 0.372 respectively. Fourteen loci are significantly deviated from Hardy Weinberg Equilibrium (HWE) at p<0.001 across the two regions. Significant linkage disequilibrium was detected in five pairs of loci at p<0.001 from 1176 loci pair combinations. P. homarus from the two regions have similar genetic diversity indices and it was found by AMOVA test that there is only 1% variation between P. homar from the two regions. This along with low genetic differentiation Fst (0.009) value and high number of migrants between regions (Nm= 2.946) reveal that there is mixing of P. homarus from the two regions. Lack of structuring was also revealed by STRUCTUE v.2.3.4 software, Phylogenetic tree constructed by Mega7 and adegenet, Netview, divMigrate (for relative migration network) R package. We conclude that there is an admixed structuring of P. homarus from the two studied regions and therefore the same fishery management measures (e.g. catch season, lobster minimum catch size, banning catching of egg-bearing females) can be applied for the management of spiny lobster fishery in the two regions.
