Genetic differentiation and gene flow of Porcellionides pruinosus (Crustacea: Isopoda: Oniscidea) in Tunisia

Abstract

Iso-enzymatic polymorphism analysis was carried out on Tunisian populations of Porcellionides pruinosus to clarify their confused taxonomic status, previously revealed by reproductive and morphological approaches. Seventeen allozyme loci were studied, using horizontal starch gel electrophoresis, in 230 adult specimens belonging to nine populations of P. pruinosus located in north, central and south Tunisia, to assess the levels of their intra-genetic and inter-genetic diversity, and to analyse their genetic structure. Our results indicate a low genetic variability with a polymorphism ratio ranging from 29.4% in Tabarka to 47.1% in the Garat Nâam and Raccada populations, and the mean number of alleles per locus was estimated at 1.51 ± 0.15. The direct-count of heterozygosity ranged between 8.1% and 15%. Substantial estimates of demic structuring were found at the total population (F_ST = 0.198), with a generalized and significant heterozygote deficiency detected in every population (with a mean value for all populations of F_IS = 0.372). Genetic distances between the studied populations were low, indicating that they belong to the same species. Nevertheless, the genetic analyses showed the divergence of the population of Tabarka from all the other studied populations, with the lowest mean gene flow, 0.58, and the highest mean genetic distance, (0.182) obtained also by the morphological and reproductive approaches.

Keywords:

• Oniscidea
• Porcellionides pruinosus
• population
• electrophoresis
• genetic diversity

Acknowledgements

We wish to thank Aziz Ben-Jebria, Professor of Chemical Engineering Bioengineering and Physiology Graduate Programs, The Pennsylvania State University, for his constructive remarks and for revising the English of the manuscript.