Rapid evolution of disease resistance is accompanied by functional changes in gene expression in a wild bird


Bonneaud C, Balenger SL, Russell AF, Zhang J, Hill GE, Edwards SV. Rapid evolution of disease resistance is accompanied by functional changes in gene expression in a wild bird. Proceedings of the National Academy of Sciences of the United States of America [Internet]. 2011;108 (19) :7866-7871.


Wild organisms are under increasing pressure to adapt rapidly to
environmental changes. Predicting the impact of these changes on
natural populations requires an understanding of the speed with
which adaptive phenotypes can arise and spread, as well as of
the underlying mechanisms. However, our understanding of these
parameters is poor in natural populations. Here we use experimen-
tal and molecular approaches to investigate the recent emergence
of resistance in eastern populations of North American house
nches (
Carpodacus mexicanus
Mycoplasma galliseptum
a severe conjunctivitis-causing bacterium. Two weeks following an
US populations with a 12-y history of exposure to MG harbored
33% lower MG loads in their conjunctivae than
nches from west-
ern US populations with no prior exposure to MG. Using a cDNA
microarray, we show that this phenotypic difference in resistance
was associated with differences in splenic gene expression, with
nchesfromthe exposedpopulations up-regulatingimmunegenes
postinfection and those from the unexposed populations generally
down-regulating them. The expression response of western US
birds to experimental infection in 2007 was more similar to that
of the eastern US birds studied in 2000, 7 y earlier in the epizootic,
than to that of eastern birds in 2007. These results support the
hypothesis that resistance has evolved by natural selection in the
that host resistance arose and spread from standing genetic varia-
tion in the eastern US and highlight that natural selection can lead
to rapid phenotypic evolution in populations when acting on

such variation

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