Long-term survival of a urodele amphibian despite depleted major histocompatibility complex variation.
Depletion of polymorphism at major histocompatibility complex (MHC) genes has been hypothesized to limit the ability of populations to respond to emerging pathogens, thus putting their survival at risk. As pathogens contribute substantially to the global amphibian decline, assessing patterns of MHC variation is important in devising conservation strategies. Here, we directly compare levels of MHC class II and neutral variation between multiple populations of the great crested newt (Triturus cristatus) from refugial (REF: Romania) and postglacial expansion (PGE: Germany, Poland and UK) areas. REF populations harboured high levels of adaptive variation (24 expressed alleles), exhibiting clear signatures of historical positive selection, which points to the overall importance of MHC class II variation in this species. On the other hand, PGE populations were extremely depauperate (two alleles) but nevertheless have survived for c. 10,000 years, since the postglacial expansion. Variation in putative MHC class II pseudogenes, microsatellites and allozymes also showed a significant southern richness-northern purity pattern. The populations in the postglacial expansion area thus provide the clearest example to date of the long-term survival of populations in which MHC variation, historically under positive selection, has been depleted.
Babik
W
W
Department of Community Ecology, Helmholtz Centre for Environmental Research-UFZ, Theodor-Lieser-Str 4, 06120 Halle/Saale, Germany. wieslaw.babik@uj.edu.pl
Pabijan
M
M
Arntzen
J W
JW
Cogâlniceanu
D
D
Durka
W
W
Radwan
J
J
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D003062:Codon / Q000235:genetics; D005060:Europe; D005786:Gene Expression Regulation; D005802:Genes, MHC Class II / Q000235:genetics; D056426:Genetic Loci / Q000235:genetics; D005843:Geography; D000949:Histocompatibility Antigens Class II / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D007527:Isoenzymes / Q000235:genetics; D008285:Major Histocompatibility Complex / Q000235:genetics* / Q000276:immunology*; D018895:Microsatellite Repeats / Q000235:genetics; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D011110:Polymorphism, Genetic; D011995:Recombination, Genetic / Q000235:genetics; D012455:Salamandridae / Q000235:genetics* / Q000276:immunology*; D012641:Selection, Genetic; D016415:Sequence Alignment; D016019:Survival Analysis; D013997:Time Factors
D003062:Codon; D000949:Histocompatibility Antigens Class II; D007527:Isoenzymes