The genetic population structure of the lagoon specialists Nematostella vectensis, Cerastoderma glaucum and Gammarus insensibilis from populations along the southern and eastern coasts of the United Kingdom

Molecular markers were used to analyses genetic variation within and between populations of three lagoon specialists: Nematostella vectensis, the lagoon sea anemone, Cerastoderma glaucum, the lagoon cockle and Gammarus insensibilis, the lagoon sand shrimp from lagoons along the southern and eastern coasts of the United Kingdom. Despite their very different life history strategies, all three species demonstrated genetic patterns associated with a high degree of isolation, combined with limited dispersal ability. The random amplified polymorphic DNA (RAPD) data, revealed the mainly asexual sea anemone, Nematostella vectensis to be predominantly clonal throughout its known U.K. range, with monoclonal or near monoclonal populations and rare genotypes confined to single sites. The microsatellite markers employed in this study indicated a high degree of genetic differentiation, severe inbreeding and the absence of Hardy-Weinberg equilibrium conditions in populations of both Cerastoderma glaucum and Gammarus insensibilis.

RAPD data from populations of N. vectensis revealed that 61% of individuals had an identical genotype, the frequency of which varied from 0.01 to 1.00. These data may provide evidence for a single ‘general-purpose’ genotype. The presence of significant linkage disequilibria (p<0.05) in populations of C. glaucum and in populations of G. insensibilis, moreover, provides further support for a ‘general-purpose’ genotype associated with the lagoon habitat. Additional evidence for such a genotype comes from the extreme excess of homozygosity (two loci showed significantly less observed than expected heterozygosity for all populations: p<0.01) in C. glaucum, and extreme excess of heterozygosity (fixed heterozygosity for one locus in all populations; p<0.01 and fixed heterozygosity for two loci in one other population; p<0.01) in G. insensibilis.

Colonisation to lagoons probably occurs across open water.

University of Southampton

Pearson, Catherine

cc158843-35b0-4ce2-9979-a08e698da6b9

2003

Pearson, Catherine

cc158843-35b0-4ce2-9979-a08e698da6b9

Pearson, Catherine (2003) The genetic population structure of the lagoon specialists Nematostella vectensis, Cerastoderma glaucum and Gammarus insensibilis from populations along the southern and eastern coasts of the United Kingdom. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)