Chronic malaria infections increase family inequalities and reduce parental fitness: experimental evidence from a wild bird population
Chronic malaria infections increase family inequalities and reduce parental fitness: experimental evidence from a wild bird population
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DOI：
10.1111/j.1420-9101.2009.01920.x
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发表时间：
2010-03-01
影响因子：
2.1
通讯作者：
Sheldon, B. C.
中科院分区：
文献类型：
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作者：
Knowles, S. C. L.;Palinauskas, V.;Sheldon, B. C.
鸟类疟疾寄生虫（疟原虫）通常发生在野生鸟类中，是一个越来越受欢迎的模型系统，用于了解宿主-寄生虫的共同进化。然而，这些寄生虫是否有健身的后果，在流行地区的主机有很大的争议，特别是因为野生捕获的个人几乎总是海港慢性感染的寄生虫密度非常低。我们使用抗疟疾药物Malarone（TM）在一个野生种群的繁殖蓝山雀（Cyanistes caeruleus）的慢性疟疾感染的健身效果进行实验测试。药物治疗引起疟原虫感染强度的显著降低，通常导致这些寄生虫从血液中完全清除，如定量PCR所示。在繁殖过程中的多个阶段发现药物对疟疾感染的鸟类的积极影响，与对照组相比，药物治疗的雌性显示出更高的孵化成功率，供应率和羽翼成功率。最引人注目的是，我们发现，母亲疟疾感染的治疗强烈改变了家庭内的差异，减少不平等的孵化概率和羽翼未丰的质量内育雏用药的女性。这些内育雏的影响似乎解释了较高的初出茅庐的成功用药的女性，并与父母的乐观模式，其中较小的（边缘）后代可以成功地提高到独立的，如果额外的资源成为在育种尝试。总体而言，这些结果表明，慢性禽疟疾感染，远远不是良性的，可以有显着的影响主机健身，因此可能构成一个重要的选择压力，在野生鸟类种群。
Avian malaria parasites (Plasmodium) occur commonly in wild birds and are an increasingly popular model system for understanding host-parasite co-evolution. However, whether these parasites have fitness consequences for hosts in endemic areas is much debated, particularly since wild-caught individuals almost always harbour chronic infections of very low parasite density. We used the anti-malarial drug Malarone (TM) to test experimentally for fitness effects of chronic malaria infection in a wild population of breeding blue tits (Cyanistes caeruleus). Medication caused a pronounced reduction in Plasmodium infection intensity, usually resulting in complete clearance of these parasites from the blood, as revealed by quantitative PCR. Positive effects of medication on malaria-infected birds were found at multiple stages during breeding, with medicated females showing higher hatching success, provisioning rates and fledging success compared to controls. Most strikingly, we found that treatment of maternal malaria infections strongly altered within-family differences, with reduced inequality in hatching probability and fledging mass within broods reared by medicated females. These within-brood effects appear to explain higher fledging success among medicated females and are consistent with a model of parental optimism in which smaller (marginal) offspring can be successfully raised to independence if additional resources become available during the breeding attempt. Overall, these results demonstrate that chronic avian malaria infections, far from being benign, can have significant effects on host fitness and may thus constitute an important selection pressure in wild bird populations.