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

Publication Title

Proceedings of the Royal Society B: Biological Sciences

Document Type


Department or Program


Publication Date



Genetic compatibility, Immunocompetence, Inbreeding avoidance, Major histocompatibility complex, Microsatellites


The major histocompatibility complex (MHC) is a polymorphic gene family associated with immune defence, and it can play a role in mate choice. Under the genetic compatibility hypothesis, females choose mates that differ genetically from their own MHC genotypes, avoiding inbreeding and/or enhancing the immunocompetence of their offspring. We tested this hypothesis of disassortative 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, suggesting the amplification of two genes. MHC similarity between mates was not significantly different between pairs that did (n 1/4 4) or did not (n 1/4 42) exhibit extra-pair paternity. Comparing all mated pairs to a distribution based on randomized re-pairings, we observed the following (i): no evidence for mate choice based on maximal or intermediate levels of MHC allele sharing (ii), significantly disassortative mating based on similarity of MHC amino acid sequences, and (iii) no evidence for mate choice based on microsatellite alleles, as measured by either allele sharing or similarity in allele size. This suggests that females choose mates that differ genetically from themselves at MHC loci, but not as an inbreeding-avoidance mechanism. © 2012 The Royal Society.


Original version is available from the publisher at: https://doi.org/10.1098/rspb.2011.0562

Copyright Note

Copyright © 2011 The Royal Society