Department of Bird Migration, Swiss Ornithological Institute, Seerose 1, 6204 Sempach, Switzerland.
CESAM - Centre for Environmental and Marine Studies, Department of Biology, University of Aveiro, Campus Universitário de Santiago, 3810 193 Aveiro, Portugal; South Iceland Research Centre, University of Iceland, Lindarbraut 4, 840 Laugarvatn, Iceland.
Int J Parasitol. 2020 Dec;50(14):1125-1131. doi: 10.1016/j.ijpara.2020.07.005. Epub 2020 Aug 29.
Amongst other factors, host behaviour critically determines the patterns with which blood parasites occur in wild host populations. In particular, migratory hosts that sequentially occupy distant sites within and across years are expected to show distinct patterns of blood parasitism depending on their population-specific schedules and whereabouts. Here, we monitored haemosporidian parasitism in two populations of European bee-eaters (Merops apiaster), breeding in Portugal and Germany, with fundamentally different spatiotemporal migration patterns and colonisation histories. We describe and compare the composition of their parasite fauna as well as host population-, age- and sex-specific patterns in the frequency and intensity of infections. We found haemosporidian prevalence to be higher in Portugal compared with Germany and the prevalence generally increased with host age in both populations. Bee-eaters breeding in Portugal and wintering in western Africa mostly hosted parasites of the genus Haemoproteus, while Plasmodium lineages prevailed in birds breeding in Germany and wintering in central Africa. We found 18 genetic lineages, of which nine uniquely occurred in Germany, three uniquely in Portugal and six occurred in both breeding populations. The infection intensities (= % infected per inspected erythrocytes) ranged from 0.002% up to maximally 2.5% in Portugal and 9.6% in Germany. The intensity was higher in Germany compared with Portugal, vastly varied between the parasite genera (Haemoproteus > Plasmodium), but also differed between lineages of the same genus. Our results suggest that populations from different parts of a host's breeding range differ in prevalence and the composition of their haemosporidian assemblages, rather than in the intensity of their infections. Whether these patterns are mainly caused by differential habitat use throughout the annual cycle and/or the population-specific co-evolutionary backgrounds of a host species in range expansion remains to be elucidated.
在其他因素中，宿主行为极大地决定了血液寄生虫在野生宿主群体中的出现模式。特别是那些在年际间顺序占据不同地点的迁徙宿主，预计会根据其特定的种群时间表和栖息地，表现出不同的血液寄生虫感染模式。在这里，我们监测了在葡萄牙和德国繁殖的欧洲食蜂鸟（Merops apiaster）的两种种群中的血液寄生虫寄生情况，它们具有截然不同的时空迁徙模式和殖民化历史。我们描述并比较了它们寄生虫区系的组成，以及宿主种群、年龄和性别特异性的感染频率和强度模式。我们发现，葡萄牙的血液寄生虫患病率高于德国，而且在两个种群中，患病率通常随着宿主年龄的增长而增加。在葡萄牙繁殖、在西非越冬的食蜂鸟主要携带 Haemoproteus 属的寄生虫，而在德国繁殖、在中非越冬的鸟类中则以 Plasmodium 谱系为主。我们发现了 18 个遗传谱系，其中 9 个仅在德国出现，3 个仅在葡萄牙出现，6 个在两个繁殖种群中都出现。感染强度（= 每检查 1000 个红细胞中的感染百分比）在葡萄牙从 0.002%到最大值 2.5%不等，而在德国为 9.6%。德国的感染强度高于葡萄牙，不同寄生虫属之间（Haemoproteus>Plasmodium）差异很大，但同一属的不同谱系之间也存在差异。我们的研究结果表明，来自宿主繁殖范围不同地区的种群在患病率和血液寄生虫组合的组成上存在差异，而不是感染的强度。这些模式主要是由于宿主在整个年周期中对不同栖息地的利用差异，还是由于宿主物种在种群扩张过程中的特定协同进化背景造成的，仍有待阐明。
