naa a22 4500 52878353X 20180924065515.0 cr unu---uuuuu 180924e20100616xx s 000 0 eng 10.3929/ethz-b-000028083 doi 10.1371/journal.pone.0010948 doi (ETHRESEARCH)oai:www.research-collection.ethz.ch:20.500.11850/28083 Sympatric and Allopatric Divergence of MHC Genes in Threespine Stickleback [Elektronische Daten] [Matthews Blake, Luke J. Harmon, Leithen M'Gonigle, Kerry B. Marchinko, Helmut Schaschl] PLoS ONE Open access ethresearch 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 Histocompatability 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. Creative Commons Attribution 3.0 Unported http://creativecommons.org/licenses/by/3.0 ethresearch Blake Matthews joint author Harmon Luke J. joint author M'Gonigle Leithen joint author Marchinko Kerry B. joint author Schaschl Helmut joint author PLoS ONE Lawrence, Kan. : Public Library of Science 5 (6), p. e10948 1932-6203 http://hdl.handle.net/20.500.11850/28083 text/html WWW-Backlink auf das Repository (Open access) 1 Journal Article ethresearch ETHRESEARCH 856 40 http://hdl.handle.net/20.500.11850/28083 text/html WWW-Backlink auf das Repository (Open access) ETHRESEARCH 700 1- Blake Matthews joint author ETHRESEARCH 700 1- Harmon Luke J. joint author ETHRESEARCH 700 1- M'Gonigle Leithen joint author ETHRESEARCH 700 1- Marchinko Kerry B. joint author ETHRESEARCH 700 1- Schaschl Helmut joint author ETHRESEARCH 773 0- PLoS ONE Lawrence, Kan. : Public Library of Science 5 (6), p. e10948 1932-6203 BK010053 XK010053 XK010000 ETHRESEARCH ETHRESEARCH ETHRESEARCH Journal Article Open access