Departamento de Ecología Funcional y Evolutiva, Estación Experimental de Zonas Aridas (CSIC), E-4120 Almeria, Spain.
Ecology. 2013 Jun;94(6):1338-46. doi: 10.1890/12-1350.1.
Environmental characteristics of neighboring locations are generally more similar than those of distant locations. Selection pressures due to parasitism and other environmental conditions shape life history traits of hosts; thus, the probability of parasitism should be associated with the strength of spatial autocorrelation in life history and defensive traits of their hosts. Here we test this hypothesis in three different subpopulations of Magpie (Pica pica) parasitized by the Great Spotted Cuckoo (Clamator glandarius) during three breeding seasons. In some of the years and study plots, we found evidence of positive spatial autocorrelations for clutch size and parasitism rate, but not for laying date. As predicted, brood parasitism was associated with the strength of these spatial autocorrelations. Magpies that bred close to each other in areas of high risk of parasitism responded similarly to experimental parasitic eggs. Moreover, an elevated risk of parasitism eliminated the spatial autocorrelation for clutch size, which became randomly distributed. We discuss possible mechanisms explaining these associations, which may have important consequences for estimating evolutionary responses of hosts to parasitic infections and, therefore, for epidemiological, ecological, and evolutionary studies of host-parasite relationships.
相邻位置的环境特征通常比遥远位置的更相似。由于寄生虫和其他环境条件的选择压力，宿主的生活史特征会发生变化；因此，寄生虫的概率应该与宿主生活史和防御特征的空间自相关强度有关。在这里，我们在三个不同的喜鹊（Pica pica）亚种群中检验了这一假设，这些喜鹊在三个繁殖季节中被大斑啄木鸟（Clamator glandarius）寄生。在一些年份和研究区域，我们发现窝卵数和寄生率存在正空间自相关的证据，但产卵日期没有。正如预测的那样，巢寄生与这些空间自相关的强度有关。在高寄生风险地区彼此靠近繁殖的喜鹊对实验寄生卵的反应相似。此外，寄生风险的增加消除了窝卵数的空间自相关，使其呈随机分布。我们讨论了可能的解释这些关联的机制，这些机制可能对估计宿主对寄生虫感染的进化反应具有重要意义，因此对宿主-寄生虫关系的流行病学、生态学和进化研究具有重要意义。
