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Wayne Potts
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At the broadest level
my research interests focus on the genetics of natural and sexual selection. My
current research efforts focus on the genes of the major histocompatibility complex
(MHC). MHC genes play a central role in immune recognition, but they have also
been shown to influence individual odors and reproductive traits such as mating
preferences and spontaneous abortion. MHC genes are also the most polymorphic
loci known for vertebrates. This extreme genetic diversity has the following
relatively unique features:
1. There are a large number of alleles per locus, often over 100.
2. The sequence diversification between alleles is extreme, with some alleles
differing by as much as 30%, a degree of divergence normally found between
homologous gene sequences taken from taxa as distant as birds and
mammals.
3. This allelic sequence diversification results because MHC allelic lineages are
ancient, more ancient than recent speciation events. So, for example, any
given human MHC allele is more related to some alleles from chimpanzees
and gorillas than it is to most other human alleles.
4. Antigen binding site codons show a high rate of substitutions that change the
amino acid sequence, indicating that new antigenic profiles are being
favored. It can be demonstrated that to account for each of the above features
some form of natural selection acting on the antigen binding site is required.
What is the nature of the selection acting on MHC genes? Answering this question is
a central focus of my laboratory and leads to at least four major levels of inquiry
involving host-parasite interactions, inbreeding, sexual selection and kin recognition
systems. Our current understanding suggests the following relationships. Parasitedriven selection favors MHC genetic diversity through both heterozygote advantage
and frequency dependent selection. This in turn favors the evolution of MHC-based