Mathematical Biology seminar
Wayne Potts
Dept of Biology
"Pathogens, mutations, sexual selection and histocompatibility
polymorphisms"
October 12, 2005
3:05pm, LCB 215
Genes of the major histocompatibility complex (MHC) play a central
role in immune recognition, but they also 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) large number of alleles per locus, often over 100,
(2) extreme sequence diversification between alleles and
(3) high rates of non-synonymous substitutions at antigen-binding-site
codons.
To account for each of the above features at least two forms of natural
selection are required. What is the nature of this selection? Current
understanding suggests the following relationships. Parasite-driven
selection favors MHC genetic diversity through both heterozygote
advantage and evasion of MHC-mediated immune recognition. This in
turn favors the evolution of MHC-based disassortative mating preferences
(etc.) because such matings produce high-quality progeny. Such mating
preferences would further increase MHC genetic diversity, making these
loci increasingly useful as a kin recognition marker. Consequently,
the avoidance of matings with kin (i.e. inbreeding) is an additional
factor favoring MHC-based mating preferences. The relative importance
of these hypothesized interactions is controversial. I will present
results from experimental tests of each hypothesis.
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Mathematical Biology Program
Department of Mathematics
University of Utah
155 South 1400 East Room 233
Salt Lake City, UT 84112
rasmusse@math.utah.edu
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