class="kwd-title">Keywords: Food web, Parasitism, Diversity, Life cycle, Community class="head no_bottom_margin" id="idm140160092295616title">AbstractAs the data have poured in, and the number of published food webs containing parasites has increased, questions have been raised as to why free-living species consistently outnumber parasites, even though most general reviews on the subject of host:parasite species richness suggest the contrary. Here, I describe this pattern as it exists in the literature, posit both real and artifactual sources of these findings, and suggest ways that we might interpret existing parasite-inclusive food webs. In large part, the reporting of free-living species devoid of any associated parasites (termed here in the coding of food web matrices as “zeros”) is a consequence of either sampling issues or the intent of the study. However, there are also several powerful explanatory features that validate real cases of this phenomenon. Some hosts appear to authentically lack parasitism in portions of their geographic ranges, and parasites are often lost from systems that are either in early phases of community re-colonization or are compromised by environmental perturbation. Additionally, multi-stage parasite life cycles and broad host spectra allow some parasite species to partially saturate systems without providing a corresponding increase in parasite species richness, leading to low parasite species richness values relative to the free-living community. On the whole, the existing published food webs are sufficient to, at least in principle, determine basic patterns and pathways associated with parasite establishment and persistence in free-living communities because (1) for the purpose of those features, species rarity is roughly analogous to absence and (2) the existing data seem to suggest that the addition of more parasite taxa would reinforce the patterns already observed. This is particularly true for helminth parasites, in which our understanding and the resolution of our work is most robust.
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机译：<！-fig ft0-> <！-fig @ position =“ anchor” mode =文章f4-> <！-fig mode =“ anchred” f5-> <！-fig / graphic | fig / alternatives / graphic mode =“ anchored” m1-> class =“ kwd-title”>关键字：食物网，寄生虫，多样性，生命周期，社区 class =“ head no_bottom_margin” id =随着数据的涌入以及包含寄生虫的已发表食物网的数量增加，人们提出了一个问题，即尽管大多数人对此的一般性评论，但为什么自由生活物种的数量总是超过寄生虫的数量。寄主的主题：寄生虫物种丰富度提示相反。在这里，我描述了这种存在于文献中的模式，假定了这些发现的真实和人工来源，并提出了我们可以解释现有的包括寄生虫在内的食物网的方式。在很大程度上，报告中没有任何相关寄生虫的自由生存物种（这里在食品网矩阵编码中称为“零”）是抽样问题或研究意图的结果。但是，也有一些强大的解释功能可以验证这种现象的真实情况。一些寄主似乎确实在其部分地理范围内没有寄生虫，并且寄生虫经常从处于社区重新殖民化早期阶段或因环境扰动而受损的系统中流失。此外，多阶段寄生虫的生命周期和广泛的宿主谱使某些寄生虫物种能够部分饱和，而不会提供相应的寄生虫物种丰富度增加，从而导致相对于自由生活社区而言，寄生虫物种丰富度值较低。总体而言，现有已发布的食物网至少足以在原则上确定与寄生虫的建立和在自由生活社区中的持久性相关的基本模式和途径，因为（1）就这些特征而言，物种稀有性大致相似（2）现有数据似乎表明增加更多的寄生生物分类群将加强已经观察到的模式。对于蠕虫寄生虫尤其如此，因为在这种寄生虫中，我们的理解和对工作的决心最为坚定。
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