Sympatric and allopatric divergence of MHC genes in threespine stickleback.
Parasites can strongly affect the evolution of their hosts, but their effects on host diversification are less clear. In theory, contrasting parasite communities in different foraging habitats could generate divergent selection on hosts and promote ecological speciation. Immune systems are costly to...
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doaj-6969a8c3fb284e58a2578d234a78c5452020-11-25T01:57:37ZengPublic Library of Science (PLoS)PLoS ONE1932-62032010-06-0156e1094810.1371/journal.pone.0010948Sympatric and allopatric divergence of MHC genes in threespine stickleback.Blake MatthewsLuke J HarmonLeithen M'GonigleKerry B MarchinkoHelmut SchaschlParasites can strongly affect the evolution of their hosts, but their effects on host diversification are less clear. In theory, contrasting parasite communities in different foraging habitats could generate divergent selection on hosts and promote ecological speciation. Immune systems are costly to maintain, adaptable, and an important component of individual fitness. As a result, immune system genes, such as those of the Major Histocompatibility Complex (MHC), can change rapidly in response to parasite-mediated selection. In threespine stickleback (Gasterosteus aculeatus), as well as in other vertebrates, MHC genes have been linked with female mating preference, suggesting that divergent selection acting on MHC genes might influence speciation. Here, we examined genetic variation at MHC Class II loci of sticklebacks from two lakes with a limnetic and benthic species pair, and two lakes with a single species. In both lakes with species pairs, limnetics and benthics differed in their composition of MHC alleles, and limnetics had fewer MHC alleles per individual than benthics. Similar to the limnetics, the allopatric population with a pelagic phenotype had few MHC alleles per individual, suggesting a correlation between MHC genotype and foraging habitat. Using a simulation model we show that the diversity and composition of MHC alleles in a sympatric species pair depends on the amount of assortative mating and on the strength of parasite-mediated selection in adjacent foraging habitats. Our results indicate parallel divergence in the number of MHC alleles between sympatric stickleback species, possibly resulting from the contrasting parasite communities in littoral and pelagic habitats of lakes.http://europepmc.org/articles/PMC2886830?pdf=render |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Blake Matthews Luke J Harmon Leithen M'Gonigle Kerry B Marchinko Helmut Schaschl |
spellingShingle |
Blake Matthews Luke J Harmon Leithen M'Gonigle Kerry B Marchinko Helmut Schaschl Sympatric and allopatric divergence of MHC genes in threespine stickleback. PLoS ONE |
author_facet |
Blake Matthews Luke J Harmon Leithen M'Gonigle Kerry B Marchinko Helmut Schaschl |
author_sort |
Blake Matthews |
title |
Sympatric and allopatric divergence of MHC genes in threespine stickleback. |
title_short |
Sympatric and allopatric divergence of MHC genes in threespine stickleback. |
title_full |
Sympatric and allopatric divergence of MHC genes in threespine stickleback. |
title_fullStr |
Sympatric and allopatric divergence of MHC genes in threespine stickleback. |
title_full_unstemmed |
Sympatric and allopatric divergence of MHC genes in threespine stickleback. |
title_sort |
sympatric and allopatric divergence of mhc genes in threespine stickleback. |
publisher |
Public Library of Science (PLoS) |
series |
PLoS ONE |
issn |
1932-6203 |
publishDate |
2010-06-01 |
description |
Parasites can strongly affect the evolution of their hosts, but their effects on host diversification are less clear. In theory, contrasting parasite communities in different foraging habitats could generate divergent selection on hosts and promote ecological speciation. Immune systems are costly to maintain, adaptable, and an important component of individual fitness. As a result, immune system genes, such as those of the Major Histocompatibility Complex (MHC), can change rapidly in response to parasite-mediated selection. In threespine stickleback (Gasterosteus aculeatus), as well as in other vertebrates, MHC genes have been linked with female mating preference, suggesting that divergent selection acting on MHC genes might influence speciation. Here, we examined genetic variation at MHC Class II loci of sticklebacks from two lakes with a limnetic and benthic species pair, and two lakes with a single species. In both lakes with species pairs, limnetics and benthics differed in their composition of MHC alleles, and limnetics had fewer MHC alleles per individual than benthics. Similar to the limnetics, the allopatric population with a pelagic phenotype had few MHC alleles per individual, suggesting a correlation between MHC genotype and foraging habitat. Using a simulation model we show that the diversity and composition of MHC alleles in a sympatric species pair depends on the amount of assortative mating and on the strength of parasite-mediated selection in adjacent foraging habitats. Our results indicate parallel divergence in the number of MHC alleles between sympatric stickleback species, possibly resulting from the contrasting parasite communities in littoral and pelagic habitats of lakes. |
url |
http://europepmc.org/articles/PMC2886830?pdf=render |
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