MHC genetic structure and divergence across populations of Chinook salmon (Oncorhynchus tshawytscha)

Evans, Melissa L.; Neff, Bryan D.; Heath, Daniel D.

doi:10.1038/hdy.2009.121

Cited by 38 publications

(40 citation statements)

References 84 publications

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“…During the larvae stage in the Quinsam population, we found evidence that offspring with lower MHC class II nucleotide divergence survived better than expected under our null hypothesis. We have previously reported that MHC class II genetic variation is dominated by a single allele in several Chinook salmon populations in British Columbia, including the Quinsam and Big Qualicum populations studied here (Evans et al 2010; also see Miller et al 1997;Neff et al 2008). This low diversity may reflect directional selection for a ''good gene'' in these populations (Neff and Pitcher 2005;Pitcher and Neff 2006).…”

Section: Discussionmentioning

confidence: 57%

“…These alignments were used to identify the nucleotides that encode the putative PBR-the nucleotides directly involved in the binding of pathogens-in Chinook salmon based on the known PBR in the human HLA. Sequences were also aligned to previously reported Chinook salmon MHC class I-A1 or II-B1 alleles (Evans et al 2010). …”

Section: Mhc Genotypingmentioning

confidence: 99%

“…The populations are located on the east coast of Vancouver Island and are separated by approximately 100 km. Population divergence between the Big Qualicum and Quinsam rivers is higher at the MHC class I and lower at the MHC class II than expected under neutrality, which suggests that these populations are undergoing local adaptation through potentially differing forms of selection (Evans et al 2010). Indeed, Chinook salmon juveniles in the Quinsam and Big Qualicum rivers may face differing levels of infections by a highly diverse bacterial pathogen community (Evans and Neff 2009).…”

Section: Introductionmentioning

confidence: 99%

“…The MHC has been shown to display considerable genetic variation within and among populations in many vertebrates including birds, mammals, and fishes (e.g. Wegner et al 2003;Bryja et al 2007;Ekblom et al 2007;Evans et al 2010) and this diversity is likely to have arisen in response to variation in the pathogen community (Apanius et al 1997).…”

Section: Introductionmentioning

confidence: 99%

“…Hedrick et al 2001;Froeschke and Sommer 2005; see Wegner et al 2004 for a review) or that there is an excess of heterozygotes within populations, which suggests a selective advantage for heterozygotes (e.g. Peters and Turner 2008;Oliver et al 2009;Evans et al 2010;see Apanius et al 1997;Garrigan and Hedrick 2003 for reviews). Furthermore, individuals bearing more divergent MHC alleles may be able to recognize a broader range of pathogens than individuals bearing more similar MHC alleles (Wakeland et al 1990).…”

Section: Introductionmentioning

confidence: 99%

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MHC-mediated local adaptation in reciprocally translocated Chinook salmon

2010

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Most Pacific salmonid populations have faced significant population declines over the past 30 years. In order to effectively conserve and manage these populations, knowledge of the evolutionary adaptive state of individuals and the scale of adaptation across populations is needed. The vertebrate major histocompatibility complex (MHC) represents an important adaptation to parasites, and genes encoding for the MHC are widely held to be undergoing balancing selection. However, the generality of balancing selection across populations at MHC loci is not well documented. Using Chinook salmon (Oncorhynchus tshawytscha) from two populations, we follow the survival of full-sib family replicates reared in their natal river and reciprocally transplanted to a foreign river to examine selection and local adaptation at the MHC class I and II loci. In both populations, we found evidence of a survivorship advantage associated with nucleotide diversity at the MHC class I locus. In contrast, we found evidence that MHC class II diversity was disadvantageous in one population. There was no evidence that these effects occurred in translocated families, suggesting some degree of local adaptation at the MHC loci. Thus, our results implicate balancing selection at the MHC class I but potentially differing selection across populations at the class II locus.

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Section: Discussionmentioning

confidence: 57%

Section: Mhc Genotypingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

MHC-mediated local adaptation in reciprocally translocated Chinook salmon

2010

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Combining molecular evolution and environmental genomics to unravel adaptive processes of MHC class IIB diversity in European minnows (Phoxinus phoxinus)

Collin

Burri

Comtesse

et al. 2013

Ecology and Evolution

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Host-pathogen interactions are a major evolutionary force promoting local adaptation. Genes of the major histocompatibility complex (MHC) represent unique candidates to investigate evolutionary processes driving local adaptation to parasite communities. The present study aimed at identifying the relative roles of neutral and adaptive processes driving the evolution of MHC class IIB (MHCIIB) genes in natural populations of European minnows (Phoxinus phoxinus). To this end, we isolated and genotyped exon 2 of two MHCIIB gene duplicates (DAB1 and DAB3) and 1′665 amplified fragment length polymorphism (AFLP) markers in nine populations, and characterized local bacterial communities by 16S rDNA barcoding using 454 amplicon sequencing. Both MHCIIB loci exhibited signs of historical balancing selection. Whereas genetic differentiation exceeded that of neutral markers at both loci, the populations' genetic diversities were positively correlated with local pathogen diversities only at DAB3. Overall, our results suggest pathogen-mediated local adaptation in European minnows at both MHCIIB loci. While at DAB1 selection appears to favor different alleles among populations, this is only partially the case in DAB3, which appears to be locally adapted to pathogen communities in terms of genetic diversity. These results provide new insights into the importance of host-pathogen interactions in driving local adaptation in the European minnow, and highlight that the importance of adaptive processes driving MHCIIB gene evolution may differ among duplicates within species, presumably as a consequence of alternative selective regimes or different genomic context.

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Can balancing selection on MHC loci counteract genetic drift in small fragmented populations of black grouse?

Strand

Segelbacher

Quintela

et al. 2012

Ecology and Evolution

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The ability of natural populations to adapt to new environmental conditions is crucial for their survival and partly determined by the standing genetic variation in each population. Populations with higher genetic diversity are more likely to contain individuals that are better adapted to new circumstances than populations with lower genetic diversity. Here, we use both neutral and major histocompatibility complex (MHC) markers to test whether small and highly fragmented populations hold lower genetic diversity than large ones. We use black grouse as it is distributed across Europe and found in populations with varying degrees of isolation and size. We sampled 11 different populations; five continuous, three isolated, and three small and isolated. We tested patterns of genetic variation in these populations using three different types of genetic markers: nine microsatellites and 21 single nucleotide polymorphisms (SNPs) which both were found to be neutral, and two functional MHC genes that are presumably under selection. The small isolated populations displayed significantly lower neutral genetic diversity compared to continuous populations. A similar trend, but not as pronounced, was found for genotypes at MHC class II loci. Populations were less divergent at MHC genes compared to neutral markers. Measures of genetic diversity and population genetic structure were positively correlated among microsatellites and SNPs, but none of them were correlated to MHC when comparing all populations. Our results suggest that balancing selection at MHC loci does not counteract the power of genetic drift when populations get small and fragmented.

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MHC genetic structure and divergence across populations of Chinook salmon (Oncorhynchus tshawytscha)

Cited by 38 publications

References 84 publications

MHC-mediated local adaptation in reciprocally translocated Chinook salmon

MHC-mediated local adaptation in reciprocally translocated Chinook salmon

Combining molecular evolution and environmental genomics to unravel adaptive processes of MHC class IIB diversity in European minnows (Phoxinus phoxinus)

Can balancing selection on MHC loci counteract genetic drift in small fragmented populations of black grouse?

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