Table 1.
MHC and neutral variation in natural populations. Npop – number of studied populations; Nind – number of studied individuals. The evidence for historical selection on MHC comes from a dN/dS ratio >1 in the Antigen Binding Sites (ABS); Recent selection is inferred from deviation of genotype frequencies from expected Hardy–Weinberg proportions (H–W), lack of correlation of allelic richness with that for neutral alleles (correlation), lack of significant isolation by distance (IBD), higher or lower population differentiation than for neutral alleles (FST outlier, population differentiation FST), departures of allele frequency spectra from those expected under neutrality (Ewens–Watterson (E–W) and Slatkin’s P and bottleneck tests for allele frequency data, Tajima’s D test for nucleotide sequence data).
| Species (Taxon) | Npop | Nind | Evidence for departure from neutrality |
Populations examined | |
|---|---|---|---|---|---|
| Historical | Recent (type of evidence) | ||||
| Teleosts | |||||
| Atlantic salmon (Salmo salar)a | 7 | 666 | YES (dN/dS) | YES (E–W) NO (H–W, correlation) | Comparison of land-locked and river populations |
| Brown trout (Salmo trutta)b | 9 | 180 | YES (dN/dS) | NO (Tajima D, E–W, population differentiation (FST), correlation) | Small isolated populations |
| Brown trout (Salmo trutta)c | 7 | 492 | Not estimated | YES (FST outlier significant (diversifying selection) for MHC linked microsatellite locus in large populations, in small populations effect masked by immigration) | Comparison of large populations and those that have declined in size |
| California coastal steelhead (Oncorhynchus mykiss)d | 24 | 444 | YES (dN/dS) | NO (correlation, population differentiation FST), YES (FST outlier (diversifying selection) in one of three regions) | Populations that have experienced recent declines in size |
| Gila trout (Oncorhynchus gilae gilae)e | 10 | 142 | YES (dN/dS) | NO (FST outlier) | Populations that have declined in size |
| Sockeye salmon (Oncorhynchus nerka)f | 31 | 5400 | YES (dN/dS) | YES (E–W (16% of pops), Stalkin’s P (9% of pops), population differentiation FST) | Thirty one river populations compared with one lake population |
| Amphibians | |||||
| Alpine newt (Mesotriton alpestris)g | 7 | 149 | YES (dN/dS) | NO (correlation, FST outlier) | Groups of allopatric populations of postglacial origin |
| Crested newt (Triturus cristatus)h | 7 | 100 | YES (dN/dS) | NO (correlation) | Comparison between refugial populations and populations from the postglacial expansion area |
| Birds | |||||
| Great snipe (Gallinago media)i | 10 | 175 | YES (dN/dS) | YES (Tajima’s D, high structure between regions, not explained by neutral marker diversity, IBD) | Scandinavian mountain vs. East European population |
| Lesser kestrel (Falco naumanni)j | 7 | 121 | YES (dN/dS) | YES (Tajima’s D) NO (correlation, IBD pattern) | Free ranging but fragmented wild populations |
| South island robin (Petroica australis australis)k | 3 | 26 | YES (dN/dS) | NO (correlation) | Small, bottlenecked population |
| Mammals | |||||
| Spotted suslik (Spermophilus suslicus)l | 10 | 195 | YES (dN/dS) | NO (correlation, FST outlier) | Small, bottlenecked populations |
| Water vole (Arvicola terrestris)m | 7 | 591 | YES (dN/dS) | NO (global FST outlier) YES (bottleneck, higher diversity in MHC at the phase of low population density, stronger selection at DQA1 locus, at high density phase effect masked by migration) | Demographically fluctuating populations, comparison of low and high density phase |
| Water vole (Arvicola terrestris)n | 3 | 1303 | YES (dN/dS) | YES (H–W: excess of heterozygotes in MHC but not in microsatellites; GST among metapopulations higher for MHC than for microsatellites), NO (between-year correlation of MHC and microsatellite differentiation at the metapopulation level) | Metapopulations sampled over multiple years |
References.