Proc Natl Acad Sci USA. Rapid evolution of disease resistance is accompanied by functional changes in gene expression in a wild bird

[Giuseppe]

[Source: PNAS, full text: (LINK). Abstract, edited.]

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

1. Camille Bonneaud<SUP>a</SUP>,<SUP>b</SUP>,<SUP>1</SUP>,
2. Susan L. Balenger<SUP>c</SUP>,
3. Andrew F. Russell<SUP>b</SUP>,<SUP>d</SUP>,
4. Jiangwen Zhang<SUP>e</SUP>,
5. Geoffrey E. Hill<SUP>c</SUP>, and
6. Scott V. Edwards<SUP>a</SUP>

Author Affiliations

1. <SUP>a</SUP>Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138;
2. <SUP>b</SUP>Station d'Ecologie Exp?rimentale du Centre National de la Recherche Scientifique, Unit? de Sevice et de Recherche 2936, 09200 Moulis, France;
3. <SUP>c</SUP>Department of Biological Sciences, Auburn University, Auburn, AL 36849;
4. <SUP>d</SUP>Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn, Cornwall TR10 9EZ, United Kingdom; and
5. <SUP>e</SUP>Faculty of Arts and Sciences, Information Technology Research Computing, Harvard University, Cambridge, MA 02138

1. Edited by Robert E. Ricklefs, University of Missouri, St. Louis, MO, and approved March 21, 2011 (received for review December 10, 2010)

Abstract


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 experimental and molecular approaches to investigate the recent emergence of resistance in eastern populations of North American house finches (Carpodacus mexicanus) to Mycoplasma galliseptum (MG), a severe conjunctivitis-causing bacterium. Two weeks following an experimental infection that took place in 2007, finches from eastern US populations with a 12-y history of exposure to MG harbored 33% lower MG loads in their conjunctivae than finches from western 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 finches from the exposed populations up-regulating immune genes 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 exposed populations over the 12 y of the epizootic. We hypothesize that host resistance arose and spread from standing genetic variation in the eastern US and highlight that natural selection can lead to rapid phenotypic evolution in populations when acting on such variation.

• genetic basis of resistance
• host?parasite co-evolution
• immunosuppression
• quantitative RT-PCR
• emerging disease

Footnotes

• ↵<SUP>1</SUP>To whom correspondence should be addressed: E-mail: bonneaud@dr14.cnrs.fr.

• Author contributions: C.B., G.E.H., and S.V.E. designed research; C.B. and S.L.B. performed research; C.B., A.F.R., and J.Z. analyzed data; and C.B., A.F.R., G.E.H., and S.V.E. wrote the paper.
• The authors declare no conflict of interest.
• Database deposition: Sequences reported in this paper have been deposited in the GenBank database (accession nos. bankit1324533, 1324536, 1324538, 1324542, 1324554, and GW346076?GW346170).
• This article is a PNAS Direct Submission.
• This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1018580108/-/DCSupplemental.

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