Department of Animal Behaviour, Bielefeld University, Bielefeld, Germany.
J Evol Biol. 2013 Oct;26(10):2233-43. doi: 10.1111/jeb.12221. Epub 2013 Aug 28.
Correlations between heterozygosity and fitness are frequently found but rarely well understood. Fitness can be affected by single loci of large effect which correlate with neutral markers via linkage disequilibrium, or as a result of variation in genome-wide heterozygosity following inbreeding. We explored these alternatives in the common buzzard, a raptor species in which three colour morphs differ in their lifetime reproductive success. Using 18 polymorphic microsatellite loci, we evaluated potential genetic differences among the morphs which may lead to subpopulation structuring and tested for correlations between three fitness-related traits and heterozygosity, both genome wide and at each locus separately. Despite their assortative mating pattern, the buzzard morphs were found to be genetically undifferentiated. Multilocus heterozygosity was only found to be correlated with a single fitness-related trait, infection with the blood parasite, Leucocytozoon buteonis, and this was via interactions with vole abundance and age. One locus also showed a significant relationship with blood parasite infection and ectoparasite infestation. The vicinity of this locus contains two genes, one of which is potentially implicated in the immune system of birds. We conclude that genome-wide heterozygosity is unlikely to be a major determinant of parasite burden and body condition in the polymorphic common buzzard.
杂合度与适合度之间的相关性经常被发现，但很少被很好地理解。适合度可能受到与中性标记物通过连锁不平衡相关的大效应单基因座的影响，或者由于近亲繁殖导致全基因组杂合度的变化而受到影响。我们在普通鹰（一种猛禽，其三种颜色形态在其终生繁殖成功率上存在差异）中探讨了这些替代方案。使用 18 个多态微卫星基因座，我们评估了可能导致亚种群结构的形态之间的潜在遗传差异，并测试了三个与适合度相关的特征与全基因组杂合度之间的相关性，以及在每个基因座上的相关性。尽管它们存在着选择性交配模式，但鹰的形态在遗传上是没有差异的。多基因座杂合度仅与一个与适合度相关的特征，即血液寄生虫 Leucocytozoon buteonis 的感染有关，这是通过与田鼠数量和年龄的相互作用来实现的。一个基因座也与血液寄生虫感染和体外寄生虫感染呈显著相关。这个基因座附近包含两个基因，其中一个可能与鸟类的免疫系统有关。我们的结论是，全基因组杂合度不太可能是多态普通鹰寄生虫负担和身体状况的主要决定因素。
