Allan Wilson Centre for Molecular Ecology and Evolution, School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand.
Mol Ecol. 2010 Sep;19(18):3894-908. doi: 10.1111/j.1365-294X.2010.04771.x. Epub 2010 Aug 13.
Neutral genetic markers are commonly used to understand the effects of fragmentation and population bottlenecks on genetic variation in threatened species. Although neutral markers are useful for inferring population history, the analysis of functional genes is required to determine the significance of any observed geographical differences in variation. The genes of the major histocompatibility complex (MHC) are well-known examples of genes of adaptive significance and are particularly relevant to conservation because of their role in pathogen resistance. In this study, we survey diversity at MHC class I loci across a range of tuatara populations. We compare the levels of MHC variation with that observed at neutral microsatellite markers to determine the relative roles of balancing selection, diversifying selection and genetic drift in shaping patterns of MHC variation in isolated populations. In general, levels of MHC variation within tuatara populations are concordant with microsatellite variation. Tuatara populations are highly differentiated at MHC genes, particularly between the northern and Cook Strait regions, and a trend towards diversifying selection across populations was observed. However, overall our results indicate that population bottlenecks and isolation have a larger influence on patterns of MHC variation in tuatara populations than selection.
中性遗传标记通常用于了解片段化和种群瓶颈对受威胁物种遗传变异的影响。尽管中性标记对于推断种群历史很有用，但需要分析功能基因，以确定观察到的地理变异的任何意义。主要组织相容性复合体（MHC）的基因是具有适应性意义的基因的典型例子，由于其在病原体抗性中的作用，与保护特别相关。在这项研究中，我们调查了一系列大蜥蜴种群中 MHC Ⅰ类基因座的多样性。我们比较了 MHC 变异水平与中性微卫星标记观察到的水平，以确定平衡选择、多样化选择和遗传漂变在塑造隔离种群 MHC 变异模式中的相对作用。一般来说，大蜥蜴种群内 MHC 变异的水平与微卫星变异一致。大蜥蜴种群在 MHC 基因上高度分化，特别是在北部和库克海峡地区之间，并且在整个种群中观察到多样化选择的趋势。然而，总的来说，我们的结果表明，种群瓶颈和隔离对大蜥蜴种群 MHC 变异模式的影响大于选择。
