Massive introgression of major histocompatibility complex (MHC) genes in newt hybrid zones
Massive introgression of major histocompatibility complex (MHC) genes in newt hybrid zones
复制标题
DOI：
10.1111/mec.15254
复制
发表时间：
2019-10-21
影响因子：
4.9
通讯作者：
Babik, Wieslaw
中科院分区：
文献类型：
--
作者：
Dudek, Katarzyna;Gaczorek, Tomasz S.;Babik, Wieslaw
脊椎动物主要组织相容性复合体（MHC）基因的变异对抵抗病原体的攻击至关重要。由于新的等位基因具有选择优势，因此即使在有限的杂交情况下，MHC也很容易在物种之间渗入。通过在两个杂交区复制的样条，我们证实了喀尔巴阡地区最近和正在进行的MHC I和II类的渗入。渗蚀程度与接触年龄有关。在较老的区域，物种间的MHC相似度在样带内超过了物种间的相似度，这意味着普遍的渐渗——MHC基因的大规模交换，而不限于特定的变异。在模拟中，所观察到的模式在平衡选择和杂交的共同作用下出现，而在这两个过程单独作用时则不会出现。因此，在分化的高级阶段，大量的基因渗入可以引入新的和恢复以前丢失的MHC变异，从而提高杂交类群的适应潜力。因此，MHC基因可能是在早期物种之间最后停止渐渗的。
Variation in the vertebrate major histocompatibility complex (MHC) genes is crucial for fighting pathogen assault. Because new alleles confer a selective advantage, MHC should readily introgress between species, even under limited hybridization. Using replicated transects through two hybrid zones between strongly reproductively isolated European newts, Lissotriton montandoni and L. vulgaris, we demonstrated recent and ongoing MHC class I and II introgression in the Carpathian region. The extent of introgression correlated with the age of contact. In the older zone, MHC similarity between species within transects exceeded similarity between transects within species, implying pervasive introgression - a massive exchange of MHC genes, not limited to specific variants. In simulations, the observed pattern emerged under the combined action of balancing selection and hybridization, but not when these processes acted separately. Thus, massive introgression at advanced stages of divergence can introduce novel and restore previously lost MHC variation, boosting the adaptive potential of hybridizing taxa. In consequence, MHC genes may be the last to stop introgressing between incipient species.