| 1. |
- Herdegen, Magdalena, et al.
(författare)
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Heterozygosity, sexual ornament and body size in the crested newt
- 2013
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Ingår i: Journal of Zoology. - : Wiley. - 0952-8369 .- 1469-7998. ; 291:2, s. 146-153
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Tidskriftsartikel (refereegranskat)abstract
- Both genome-wide heterozygosity and heterozygosity at major histocompatibility complex (MHC) genes are often associated with higher fitness. Recent theoretical work indicates that sexual ornaments may reveal information about individual heterozygosity, and that preference for such ornaments may benefit females via the increased heterozygosity of their progeny. Here, we used path analysis to investigate the direct and indirect (via body size used as an index of condition) effects of heterozygosity at six microsatellite loci and the MHC class II DAB gene on the size of a sexual ornament, the crest, in the crested newt Triturus cristatus. We found that microsatellite heterozygosity, but not MHC heterozygosity, significantly predicted male body size, and that male body size significantly predicted crest height. However, there was no direct effect of MHC or microsatellite heterozygosity on crest height. Furthermore, microsatellite heterozygosity significantly increased with age, indicating that it had a positive effect on survival. Overall, our results are consistent with the hypothesis that heterozygosity determines condition, and that variation in condition is expressed as variation in sexual ornamentation.
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| 2. |
- Nadachowska-Brzyska, Krystyna, et al.
(författare)
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Interspecific hybridization increases MHC class II diversity in two sister species of newts
- 2012
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Ingår i: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 21:4, s. 887-906
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Tidskriftsartikel (refereegranskat)abstract
- Our understanding of the evolutionary mechanisms generating variation within the highly polymorphic major histocompatibility complex (MHC) genes remains incomplete. Assessing MHC variation across multiple populations, of recent and ancient divergence, may facilitate understanding of geographical and temporal aspects of variation. Here, we applied 454 sequencing to perform a large-scale, comprehensive analysis of MHC class II in the closely related, hybridizing newts, Lissotriton vulgaris (Lv) and Lissotriton montandoni (Lm). Our study revealed an extensive (299 alleles) geographically structured polymorphism. Populations at the southern margin of the Lvdistribution, inhabited by old and distinct lineages (southern Lv), exhibited moderate MHC variation and strong population structure, indicating little gene flow or extensive local adaptation. Lissotriton vulgaris in central Europe and the northern Balkans (northern Lv) and almost all Lm populations had a high MHC variation. A much higher proportion of MHC alleles was shared between Lm and northern Lvthan between Lm and southern Lv. Strikingly, the average pairwise FST between northern Lv and Lm was significantly lower than between northern and southern Lv for MHC, but not for microsatellites. Thus, high MHC variation in Lm and northern Lv may result from gene flow between species. We hypothesize that the interspecific exchange of MHC genes may be facilitated by frequency-dependent selection. A marginally significant correlation between the MHC and microsatellite allelic richness indicates that demographic factors may have contributed to the present-day pattern of MHC variation, but unequivocal signatures of adaptive evolution in MHC class II sequences emphasize the role of selection on a longer timescale.
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| 3. |
- Radwan, Jacek, et al.
(författare)
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MHC diversity, malaria and lifetime reproductive success in collared flycatchers
- 2012
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Ingår i: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 21:10, s. 2469-2479
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Tidskriftsartikel (refereegranskat)abstract
- Major histocompatibility complex (MHC) genes encode proteins involved in the recognition of parasite-derived antigens. Their extreme polymorphism is presumed to be driven by co-evolution with parasites. Hostparasite co-evolution was also hypothesized to optimize within-individual MHC diversity at the intermediate level. Here, we use unique data on lifetime reproductive success (LRS) of female collared flycatchers to test whether LRS is associated with within-individual MHC class II diversity. We also examined the association between MHC and infection with avian malaria. Using 454 sequencing, we found that individual flycatchers carry between 3 and 23 functional MHC class II B alleles. Predictions of the optimality hypothesis were not confirmed by our data as the prevalence of blood parasites decreased with functional MHC diversity. Furthermore, we did not find evidence for an association between MHC diversity and LRS.
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| 4. |
- Zagalska-Neubauer, Magdalena, et al.
(författare)
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454 sequencing reveals extreme complexity of the class II Major Histocompatibility Complex in the collared flycatcher
- 2010
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Ingår i: BMC Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 10:1, s. 395-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Because of their functional significance, the Major Histocompatibility Complex (MHC) class I and II genes have been the subject of continuous interest in the fields of ecology, evolution and conservation. In some vertebrate groups MHC consists of multiple loci with similar alleles; therefore, the multiple loci must be genotyped simultaneously. In such complex systems, understanding of the evolutionary patterns and their causes has been limited due to challenges posed by genotyping. Results: Here we used 454 amplicon sequencing to characterize MHC class IIB exon 2 variation in the collared flycatcher, an important organism in evolutionary and immuno-ecological studies. On the basis of over 152,000 sequencing reads we identified 194 putative alleles in 237 individuals. We found an extreme complexity of the MHC class IIB in the collared flycatchers, with our estimates pointing to the presence of at least nine expressed loci and a large, though difficult to estimate precisely, number of pseudogene loci. Many similar alleles occurred in the pseudogenes indicating either a series of recent duplications or extensive concerted evolution. The expressed alleles showed unambiguous signals of historical selection and the occurrence of apparent interlocus exchange of alleles. Placing the collared flycatcher's MHC sequences in the context of passerine diversity revealed transspecific MHC class II evolution within the Muscicapidae family. Conclusions: 454 amplicon sequencing is an effective tool for advancing our understanding of the MHC class II structure and evolutionary patterns in Passeriformes. We found a highly dynamic pattern of evolution of MHC class IIB genes with strong signals of selection and pronounced sequence divergence in expressed genes, in contrast to the apparent sequence homogenization in pseudogenes. We show that next generation sequencing offers a universal, affordable method for the characterization and, in perspective, genotyping of MHC systems of virtually any complexity.
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