Allelic and haplotype variation of major histocompatibility complex class II DRB1 and DQB loci in the St Lawrence beluga (Delphinapterus leucas)

In order to assess levels of major histocompatibility complex (Mhc) variati on within the St Lawrence beluga (Delphinapterus leucas) the variation at t he beluga Mhc DRB1 class II locus was assessed by single-strand conformatio n polymorphism (SSCP) analysis of the peptide-binding region for 313 whales collected from 13 sampling locations across North America. In addition, sa mples from west Greenland and the St Lawrence were also typed at the DQB lo cus, allowing comparison to a previous study and assessment of linkage dise quilibrium of alleles at the two loci. Comparisons of DRB1 and DQB allele f requencies among all sampling locations indicated genetic structure (alpha < 0.005). Most of this structure resulted from differences between the diff erent wintering groups. Significant genetic structure (alpha = 0.05) exists among each pair of the following groups at both the DRB1 and DQB loci; St Lawrence, Hudson Strait, Bering Sea, Cunningham Inlet, and Davis Strait (mi nus Cunningham Inlet), except the St Lawrence and Hudson Strait for the DQB locus. In the St Lawrence population, six of the eight DRB1 alleles are pr esent representing all five known allelic lineages. Evidence of linkage dis equilibrium between the DRB1 and DQB is present in two sampling locations, the St Lawrence and Nuussuaq (alpha = 0.05). Analysis of probable DRB1-DQB haplotypes among groups of beluga suggests a haplotype reduction in the St Lawrence.