Rózsa L
Central Veterinary Institute, Department of Wildlife Diseases and Parasitology, Budapest, Hungary.
J Parasitol. 1999 Dec;85(6):1032-5.
This study introduces an individual-based model on a host-parasite assemblage to investigate whether hosts are necessarily selected for obstructing the transmission of virulent parasites to conspecifics. Contrary to the widespread notion, a host's ability to influence parasite transmission within the host population is a neutral character provided that parasite transmission routes are random, with no reference to genetic relatedness. Due to a lack of selection pressure under such circumstances, hosts may fail to evolve counteradaptations against manipulations by parasites to enhance transmission. However, vertically biased transmission (biased toward kin) selects hosts for a decrease of parasite transmission, while it is also known to select parasites to decrease virulence. Horizontally biased transmission routes (biased toward nonrelated conspecifics) select hosts to increase parasite transmission. In this case, their interests coincide with that of their virulent parasites in enhancing transmission to conspecifics. This finding yields the predictions that hosts infected by virulent pathogens, but unable to recover from disease, should be prone to emigrate from their natal territories and also to enhance transmission at a distance from their natal ranges. These results may considerably improve our understanding of the epidemiology of contagious pathogens and the evolution of social and sexual behavior in host species.
本研究引入了一个基于个体的宿主-寄生虫组合模型，以调查宿主是否必然会被选择来阻止毒性寄生虫向同种个体传播。与普遍观点相反，倘若寄生虫传播途径是随机的，且不涉及遗传相关性，那么宿主在宿主种群中影响寄生虫传播的能力是一个中性特征。在这种情况下，由于缺乏选择压力，宿主可能无法进化出对抗寄生虫操纵以增强传播的反适应机制。然而，垂直偏向传播（偏向亲属）会选择宿主来减少寄生虫传播，同时也已知会选择寄生虫来降低毒力。水平偏向传播途径（偏向非亲属同种个体）会选择宿主来增加寄生虫传播。在这种情况下，它们在增强向同种个体传播方面的利益与毒性寄生虫的利益一致。这一发现得出的预测是，感染了毒性病原体但无法从疾病中恢复的宿主应该容易从其出生地迁移出去，并且还会在远离其出生范围的地方增强传播。这些结果可能会极大地增进我们对传染性病原体流行病学以及宿主物种社会和性行为进化的理解。
