Data from: Diet quality determines interspecific parasite interactions in host populations

The widespread occurrence of multiple infections and the often vast range of nutritional resources for their hosts allow that interspecific parasite interactions in natural host populations might be determined by host diet quality. Nevertheless, the role of diet quality with respect to multispecies parasite interactions on host population level is not clear. We here tested the effect of host population diet quality on the parasite community in an experimental study using Daphnia populations. We studied the effect of diet quality on Daphnia population demography and the interactions in multispecies parasite infections of this freshwater crustacean host. The results of our experiment show that the fitness of a low-virulent microsporidian parasite decreased in low, but not in high-host-diet quality conditions. Interestingly, infections with the microsporidium protected Daphnia populations against a more virulent bacterial parasite. The observed interspecific parasite interactions are discussed with respect to the role of diet quality-dependent changes in host fecundity. This study reflects that exploitation competition in multispecies parasite infections is environmentally dependent, more in particular it shows that diet quality affects interspecific parasite competition within a single host and that this can be mediated by host population-level effects.

多种感染的普遍发生，以及宿主通常具备的广谱营养资源条件，使得自然宿主种群中的种间寄生虫相互作用可能受宿主膳食质量调控。然而，在宿主种群层面，膳食质量对多物种寄生虫相互作用的调控作用仍未明确。本研究以水蚤（Daphnia）种群为实验材料，通过受控实验探究了宿主种群膳食质量对寄生虫群落的影响；同时分析了膳食质量对该淡水甲壳类宿主的种群动态，以及其多物种寄生虫感染过程中相互作用的调控效应。实验结果显示，低毒力微孢子虫（microsporidian）的适合度在宿主膳食质量较低的环境中出现下降，而在高膳食质量条件下则无此变化。有趣的是，感染微孢子虫可使水蚤种群免受毒力更强的细菌性寄生虫的侵害。本研究结合宿主繁殖力随膳食质量变化的调控作用，对观测到的种间寄生虫相互作用展开了讨论。本研究表明，多物种寄生虫感染过程中的资源利用竞争具有环境依赖性；具体而言，膳食质量可影响单个宿主体内的种间寄生虫竞争，且该效应可通过宿主种群层面的调控机制介导。