Abstract

Genetic differentiation between populations of the dogwhelk,Nucella lapillus, from sheltered and exposed shores as shown by profiling of DNA microsatellite loci

Author(s): Talib Hussen Ali

An initial analysis of genetic diversity using Nine primer pairs of DNA microsatellite loci (Nlw2, Nlw3, Nlw8,, Nlw11, Nlw14, Nlw17,Nlw21, Nlw25, Nlw27) was carried out along theNorthWales coast, the towNucella lapillus populations is froma sheltered shore (Llanfairfechan) and that fromCable Bay is exposed. The 9 primer pairswere optimized none failed to produce amplification products under any of the conditions tested.All nine microsatellite loci tested were polymorphic for both populations and the number of alleles per population per locus ranged from 8 to 14, with a total number of 117 alleles in the global sample. Levels of genetic variabilitywere similar across samples. All individual loci, show higher observed than expected heterozygosity. The observed heterozygosity (HO) was 0.8614 and 0.8833 and expected heterozygosity (HE) across all loci per populationwas 0.8409 and 0.8533, and in the both groups HO was higher than HE for all loci. A global test for concordance with HWE revealed no deviations from HWE in any locus. FST values per locus ranged from0.007 to 0.034, and the global FST was 0.081 (P<0.001) revealing significant structuring. In the present study the distribution of genetic variability among Nucella populations estimated and characterized in tow selected spatial scales sites. The average observed heterozygosity in Nucella (Ho = 0.869) it was differ significantly using data generated by the same set of microsatellite loci, population was genetically affected. Global FST indicated genetic differentiation among populations (4%), indicating the occurrence of past and/or present gene flow among them. Analysis of molecular variance revealed that most of the genetic variation is distributed within the populations (96%), indicating that presence of high genetic exchange and ecological adaptations to different environments are important for species survival Variation at nine microsatellites loci was used to asses whether seasonal and geographical factors as well as Tributyltin (TBT)contamination have an impact on genetic diversity on Nucella lapillus populations. There were obvious genetic variations at these loci in this species (mean expected heterozygosity = 0.84 and 0.85; mean number of alleles = 10.22and 9.67), as significantly different allele frequencies were found, between samples from the two studied populations. Indicating that Nucella lapillus around North Wales comprise two genetically heterozygous populations.