Competition and coexistence in host-parasite systems: the myxomatosis case
Competition and coexistence in host-parasite systems: the myxomatosis case
复制标题
DOI：
10.1007/s10144-004-0173-0
复制
发表时间：
2004-04-01
影响因子：
1.7
通讯作者：
Bonino, N
中科院分区：
文献类型：
--
作者：
Aparicio, JP;Solari, HG;Bonino, N
在许多宿主-寄生虫系统中观察到多种寄生虫株的共循环。然而，简单的流行病学模型不能维持这种共存。在这项工作中，我们研究的病毒株共存的多发性粘液瘤的情况下。多发性粘液瘤病是欧洲兔子的一种高致死性疾病，在澳大利亚和欧洲已被用作兔子种群的生物控制。引进几年后，原来的高毒力菌株几乎完全被覆盖广泛毒力的田间菌株所取代。在这里，我们研究了几种机制，可以解释现场观察。首先，我们考虑空间异质性。任何毒株在宿主种群占据的区域内的建立都可能延迟任何上级竞争性病毒毒株的传播，从而产生长期的全球共存。另一方面，如在现场观察到的，流行病学接触中具有不同耐药水平的亚群可以维持几种不同的病毒株共同传播。第二类机制在共享一个领土的当地种群的宿主之间引入多样性。我们考虑了不同类型的宿主对粘液瘤病的耐药性：属于一个耐药性类型是一个随机的事实。还特别考虑了宿主年龄依赖性抗性。这些类型的人口异质性可以维持当地共存多年，虽然排斥发生了足够长的时间。这两种机制的共同作用可以解释为什么病毒株的多样性是持续的，以及局部共存。最后，我们简要讨论了宿主遗传动力学在系统协同进化中的影响。
Co-circulation of several strains of parasites has been observed in many host-parasite systems. However, simple epidemiological models cannot sustain this coexistence. In this work we study the coexistence of viral strains in the myxomatosis case. Myxomatosis, a highly lethal disease of the European rabbit, has been used in Australia and Europe as a biological control of rabbit populations. A few years after its introduction, the original highly virulent strains were almost completely replaced by field strains covering a wide range of virulence. Here, we study several mechanisms that may explain the field observations. First we considered spatial heterogeneity. The establishment of any strain over regions occupied by host populations may delay the spread of any superior competitive virus strain, producing global coexistence in the long term. On the other hand, sub-populations with different resistance levels in epidemiological contact, as observed in the field, can maintain several different virus strains co-circulating. The second class of mechanism introduces diversity among hosts of a local population sharing a territory. We considered different classes of host resistance to myxomatosis: belonging to a resistance class is a random fact. Host age-dependent resistance is also especially considered. These types of population heterogeneity can sustain local coexistence for many years, although exclusion takes place for long enough periods. The concurrent action of both types of mechanisms could explain why the diversity of virus strains is sustained, and the local coexistence. Finally, we briefly discuss the influence of host genetic dynamics in the coevolution of the system.