Grosholz Edwin D
Department of Integrative Biology, University of California, 94720, CA, Berkeley, USA.
Oecologia. 1993 Dec;96(3):347-353. doi: 10.1007/BF00317504.
The influence of spatial heterogeneity on the population dynamics of a naturally occurring invertebrate host-pathogen system was experimentally investigated. At ten week intervals over a two year period, I quantified the spatial distribution of natural populations of the terrestrial isopod crustacean Porcellio scaber infected with the isopod iridescent virus (IIV). During the seasonally dry periods of summer and early fall in central California, isopod populations were highly aggregated and the degree of patchiness and distance between inhabited patches was greatest. Coincident with increased patchiness and patch spacing was an increase in isopod density within patches. During the wet seasons of winter and spring, isopod population patchiness, inter-patch spacing, and within-patch density was low. Seasonal changes in virus prevalence were negatively correlated with within-patch density, patchiness, and inter-patch spacing. The influence of the spatial distribution of isopods on virus prevalence was also tested in field experiments. The virus was introduced into arrays of artificial habitat patches colonized by isopods in which interpatch distance was varied. The prevalence of resulting infections was monitored at weekly intervals. In addition, dispersal rates between artificial patches and natural patches were quantified and compared. The results showed that isopods in treatments with the smallest inter-patch spacing had the highest virus prevalence, with generally lower prevalence among isopods in more widely spaced patches. The spacing of experimental patches significantly affected virus prevalence, although the experiments did not resolve a clear relationship between patch spacing and virus prevalence. Rates of dispersal between patches decreased with increased patch spacing, and these rates did not differ significantly from dispersal between natural patches. The results suggest that rates of dispersal between isopod subpopulations may be an important component of the infection dynamics in this system. I discuss the consequences of these findings for host-pathogen dynamics in fragmented habitats, and for other ecological interactions in spatially heterogeneous habitats.
通过实验研究了空间异质性对自然存在的无脊椎动物宿主 - 病原体系统种群动态的影响。在两年时间里，每隔十周，我对感染等足类虹彩病毒（IIV）的陆生等足类甲壳动物粗糙卷甲虫自然种群的空间分布进行了量化。在加利福尼亚中部夏季和初秋季节性干旱时期，等足类种群高度聚集，斑块程度以及居住斑块之间的距离最大。与斑块程度和斑块间距增加同时出现的是斑块内等足类密度的增加。在冬季和春季的湿润季节，等足类种群的斑块程度、斑块间间距和斑块内密度较低。病毒流行率的季节性变化与斑块内密度、斑块程度和斑块间间距呈负相关。还在野外实验中测试了等足类空间分布对病毒流行率的影响。将病毒引入由等足类定殖的人工栖息地斑块阵列中，其中斑块间距离有所变化。每周监测由此产生的感染流行率。此外，对人工斑块和自然斑块之间的扩散率进行了量化和比较。结果表明，斑块间距最小的处理组中的等足类病毒流行率最高，斑块间距更大的等足类中流行率通常较低。实验斑块的间距显著影响病毒流行率，尽管实验未明确斑块间距与病毒流行率之间的关系。斑块间的扩散率随着斑块间距增加而降低，且这些速率与自然斑块间的扩散率无显著差异。结果表明，等足类亚种群之间的扩散率可能是该系统感染动态的一个重要组成部分。我讨论了这些发现对破碎栖息地中宿主 - 病原体动态以及空间异质栖息地中其他生态相互作用的影响。
