西亚试剂：Sequence-based evidence for major histocompatibility comple

Sequence-based evidence for major histocompatibility complex-disassortative mating in a colonial seabird

Juola, Frans A.; Dearborn, Donald C.

The major histocompatibility complex (MHC) is a polymorphic gene family associated with immune defence, and it can play arole in mate choice. Under the genetic compatibility hypothesis, females choose mates that differ genetically from their ownMHC genotypes, avoiding inbreeding and/or enhancing the immunocompetence of their offspring. We tested this hypothesis ofdisassortative mating based on MHC genotypes in a population of great frigatebirds (Fregata minor) by sequencing the second exon of MHC class II B. Extensive haploid cloning yielded two to four alleles per individual, suggestingthe amplification of two genes. MHC similarity between mates was not significantly different between pairs that did (n = 4) or did not (n = 42) exhibit extra-pair paternity. Comparing all 46 mated pairs to a distribution based on randomized re-pairings, we observedthe following (i): no evidence for mate choice based on maximal or intermediate levels of MHC allele sharing (ii), significantlydisassortative mating based on similarity of MHC amino acid sequences, and (iii) no evidence for mate choice based on microsatellitealleles, as measured by either allele sharing or similarity in allele size. This suggests that females choose mates that differgenetically from themselves at MHC loci, but not as an inbreeding-avoidance mechanism.