Natural Selection on Antihelminth Antibodies in a Wild Mammal Population.
Natural Selection on Antihelminth Antibodies in a Wild Mammal Population.
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野生哺乳动物种群抗蠕虫抗体的自然选择。
DOI：
10.1086/700115
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Sparks AM
中科院分区：
文献类型：
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作者：
Sparks AM
有效的免疫反应预计会通过提高对寄生虫的抵抗力来带来健康益处，但也会招致对与健康相关的特征(如繁殖)产生负面影响的能量成本。免疫反应的健康成本和收益可能取决于宿主年龄、性别和寄生虫暴露水平。很少有研究考察自然选择对免疫表型的模式在多大程度上在不同的人口群体和野外环境中变化。在这里，我们评估了自然选择对针对一种流行线虫寄生虫的三种不同功能亚型(IgA、IgE和IgG)的血浆抗体水平的影响，这些抗体是在26年来在野生大豆羊种群中测量的。我们发现，几乎没有人支持依赖环境的选择或生殖成本。然而，抗体水平与寄生虫卵计数呈负相关，与随后的存活呈正相关，尽管抗体水平与年龄和同型高度相关。抗寄生虫IgA水平的升高最能预测产卵量的减少，但这并不能预测羔羊的存活率。在成虫中，抗寄生虫免疫球蛋白水平的增加预示着卵子数量的减少，而在成年雌性中，免疫球蛋白水平也预示着越冬存活。我们的结果强调了年龄和性别相关的选择在自然界中对免疫表型的潜在重要性，并表明即使在功能相关的免疫标记物之间，选择的模式也可以不同。
An effective immune response is expected to confer fitness benefits through improved resistance to parasites but also incur energetic costs that negatively impact fitness-related traits, such as reproduction. The fitness costs and benefits of an immune response are likely to depend on host age, sex, and levels of parasite exposure. Few studies have examined the full extent to which patterns of natural selection on immune phenotypes vary across demographic groups and environments in the wild. Here, we assessed natural selection on plasma levels of three functionally distinct isotypes (IgA, IgE, and IgG) of antibodies against a prevalent nematode parasite measured in a wild Soay sheep population over 26 years. We found little support for environment-dependent selection or reproductive costs. However, antibody levels were negatively associated with parasite egg counts and positively associated with subsequent survival, albeit in a highly age- and isotype-dependent manner. Raised levels of antiparasite IgA best predicted reduced egg counts, but this did not predict survival in lambs. In adults increased antiparasite IgG predicted reduced egg counts, and in adult females IgG levels also positively predicted overwinter survival. Our results highlight the potential importance of age- and sex-dependent selection on immune phenotypes in nature and show that patterns of selection can vary even among functionally related immune markers.