Investigaton of HLA-DQB in Megaptera novaeangliae, probabilistic paternity analysis and female mating preferences

The major histocompatibility gene complex (MHC) plays an important role in the organismal immune system, autoimmunity and reproductive success. The MHC class II genes code for peptide-binding proteins on antigenpresenting cells. In this study, we investigate the gene HLA-DQB, in a population of humpback whales, (Megaptera novaeangliae) from the Gulf of Maine on the east coast of North America. This gene encodes the beta-chain of a cell surface receptor, which presents extracellular foreign antigens to Tcells. We assess the correlation of DQB exon 2 genotypes with female mating preferences for dissimilar alleles at this locus. The maintenance and the renewal of variation in the antigen binding sites is an important genetic component in the cascade leading to an appropriate immune response since this part of the MHC acts to prevent attacks by viruses, bacteria and other parasites. The more different alleles there are, the greater the chance to detect and react against various pathogens. MHC-dissassortative mating results in progeny with high heterozygosity and thus enhanced disease resistance. We approach this by sequencing the functional DQB exon 2 for 100 mother-calf pairs, as well as 100 randomly selected humpback whale samples. From the mother and calf pairs we deduce the paternal alleles. We compare the paternal allele frequencies with the random sample to see if fathers constitute a random subset of the whole population. Using the allele frequencies in the population we will simulate different scenarios of female mate choice and compare our observed data to the simulated data. The alleles present in the offspring survived already the selective pre- and postnatal environment of the calves. We will look for a correlation of specific alleles in different age classes of whales to see if there is a trend of surviving alleles.