PARASITISM AND GROUP-SIZE IN SOCIAL ANIMALS - A METAANALYSIS
PARASITISM AND GROUP-SIZE IN SOCIAL ANIMALS - A METAANALYSIS
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DOI：
10.1093/beheco/6.2.159
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发表时间：
1995-06-01
影响因子：
2.4
通讯作者：
POULIN, R
中科院分区：
文献类型：
--
作者：
COTE, IM;POULIN, R
群居动物组成的群体的规模被认为是个体为最大限度地适应能力而施加的选择压力的组合。除了常用的选择性因子(如捕食)外，越来越多的研究表明，寄生程度可能与寄主群体大小有关，寄生虫可能会影响最佳群体大小。我们使用荟萃分析来量化在已发表的研究中发现的种内相关性，这些研究发现在各种分类群中寄生虫的流行率和强度与宿主群大小之间存在着联系。我们分别考虑了传染性寄生虫和流动寄生虫，前者通过接触受感染的人或粪便传播，后者不需要宿主之间的接近即可传播。除了传播方式外，宿主群体的流动性也被视为这种关联的潜在相关性。寄主群体大小与传染性寄生虫的流行率和强度之间存在一致的正相关。相比之下，流动寄生虫的感染强度随着宿主群规模的增加而持续下降。主办方群体的流动性对这些相关性的强度或方向都没有明显的影响。虽然很少有实验研究检验寄生对宿主群大小的因果影响，但许多报告提供了强有力的间接证据，至少对于流动寄生虫来说，随着寄生虫丰度的增加，宿主群规模更大。因此，我们的结果表明，具有不同传播方式的寄生虫可以对宿主群大小进行相互冲突的选择。然而，在荟萃分析中发现的趋势在种间比较研究中并不成立，可能是因为相关物种之间在寄生作为一种选择力量的相对重要性上的差异。
The size of groups formed by social animals is thought to result from a combination of selection pressures acting on individuals to maximize their fitness. In addition to commonly-invoked selective agents (e.g., predation), a growing number of studies suggest that levels of parasitism may be related to host group size and that parasites may influence optimal group size. We used a meta-analysis to quantify the intraspecific association found in published studies between prevalence and intensity of parasitism and host group size in a variety of taxa. We considered separately contagious parasites, which are transmitted via contact with infected individuals or feces, and mobile parasites which do not need proximity among hosts for transmission. In addition to mode of transmission, host group mobility was examined as a potential correlate of the association. Consistent positive correlations were found between host group size and both the prevalence and intensity of contagious parasites. By contrast, the intensity of infection by mobile parasites consistently decreased as host group size increased. Host group mobility had no apparent effect on either the strength or the direction of these correlations. Although few experimental studies examined the causal effect of parasitism on host group size, strong circumstantial evidence was provided, at least for mobile parasites, by many reports of larger host group sizes following increases in parasite abundance. Our results therefore suggest that parasites with different modes of transmission can exert conflicting selection on host group size. The trends found in the meta-analysis, however, do not hold in interspecific comparative studies, possibly owing to differences among related species in the relative importance of parasitism as a selective force.