Document Detail


Perspective: detecting adaptive molecular polymorphism: lessons from the MHC.
MedLine Citation:
PMID:  14503614     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In the 1960s, when population geneticists first began to collect data on the amount of genetic variation in natural populations, balancing selection was invoked as a possible explanation for how such high levels of molecular variation are maintained. However, the predictions of the neutral theory of molecular evolution have since become the standard by which cases of balancing selection may be inferred. Here we review the evidence for balancing selection acting on the major histocompatibility complex (MHC) of vertebrates, a genetic system that defies many of the predictions of neutrality. We apply many widely used tests of neutrality to MHC data as a benchmark for assessing the power of these tests. These tests can be categorized as detecting selection in the current generation, over the history of populations, or over the histories of species. We find that selection is not detectable in MHC datasets in every generation, population, or every evolutionary lineage. This suggests either that selection on the MHC is heterogeneous or that many of the current neutrality tests lack sufficient power to detect the selection consistently. Additionally, we identify a potential inference problem associated with several tests of neutrality. We demonstrate that the signals of selection may be generated in a relatively short period of microevolutionary time, yet these signals may take exceptionally long periods of time to be erased in the absence of selection. This is especially true for the neutrality test based on the ratio of nonsynonymous to synonymous substitutions. Inference of the nature of the selection events that create such signals should be approached with caution. However, a combination of tests on different time scales may overcome such problems.
Authors:
Daniel Garrigan; Philip W Hedrick
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Evolution; international journal of organic evolution     Volume:  57     ISSN:  0014-3820     ISO Abbreviation:  Evolution     Publication Date:  2003 Aug 
Date Detail:
Created Date:  2003-09-23     Completed Date:  2004-01-13     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  0373224     Medline TA:  Evolution     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1707-22     Citation Subset:  IM    
Affiliation:
Department of Biology, Arizona State University, Tempe, Arizona 85287-1501, USA. garrigan@email.arizona.edu
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MeSH Terms
Descriptor/Qualifier:
Adaptation, Biological*
Alleles
Animals
Evolution, Molecular*
Genetics, Population*
Geography
Heterozygote
Major Histocompatibility Complex / genetics*
Phylogeny
Polymorphism, Genetic*
Selection, Genetic*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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