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Updated: May 25, 2026

Stability and Structure of Bat Major Histocompatibility Complex Class I with Heterologous β2-Microglobulin
Published on: March 10, 2021
New(t)s and views from hybridizing MHC genes: introgression rather than trans-species polymorphism may shape allelic
K Mathias Wegner1, Christophe Eizaguirre
1Leibniz Institute for Marine Sciences (IFM-Geomar), Evolutionary Ecology of Marine Fishes, Düsternbroker Weg 20, 24105 Kiel, Germany. mwegner@ifm-geomar.de
Abstract:
One of the key features of major histocompatibility complex (MHC) genes is the frequent occurrence of trans-species polymorphism, that is 'the passage of allelic lineages from ancestral to descendant species' (Klein et al. 2007). Selectively maintained ancestral polymorphism may, however, be hard to distinguish from introgression of MHC alleles between hybridizing species (Fig. 1). In this issue of Molecular Ecology, Nadachowska-Brzyska et al. (2012) present data that suggest that the latter can be observed in two closely related species of newts, Lissotriton vulgaris (Lv) and L. montandoni (Lm) from south-east Europe. Strikingly, allelic MHC variation displayed more structure between geographically separated populations of L. vulgaris than across species in the hybrid zone. This suggests that high MHC variation in L. montadoni may result from mainly unidirectional gene flow between species, while differentiation between northern and southern populations of L. vulgaris might reflect local adaptation.
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