Parasites may affect host demographic characteristics because they can directly or indirectly cause the death of their hosts and/or influence their reproduction. Parasitism is therefore recognized as a factor that influences the composition and structure of populations and communities. One of these behaviours is the compensatory response: the host can compensate for the parasite losses effect, modifying the reproductive effort to enhance fitness. Ovigerus female Palaemonetes argentinus was collected and sorted into two groups according to the degree of development of their embryos: newly spawned embryos and embryos ready to hatch. The number of embryos and their dry weight for each female were determined. All parts of the female body were checked for parasites. The females of P. argentinus were parasitized by Microphalus szidati. We found that parasitized females produce more embryos but had more egg loss during development and the percentage of embryonic loss was higher in the parasitized females than in non-parasitized. Parasitized females produced lighter eggs than those from uninfected females. This supports the compensatory reproduction hypothesis suggested for this species. Parasitism can change life history traits in a way that fecundity can be compensated; this co-evolution between host and parasites will be population or context dependent. Parasites are a functional part of any ecosystem and as our results show, deleting parasites in life history traits and reproduction studies in free living organisms could lead to an incomplete picture of the true processes that happen in nature.

中文翻译：

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由于 Microphallus szidati (Trematoda) 感染引起的雌性 Palaemonetes argentinus (Decapoda: Natantia) 的生殖补偿

寄生虫可能会影响宿主的人口特征，因为它们可以直接或间接导致宿主死亡和/或影响其繁殖。因此，寄生现象被认为是影响人口和社区组成和结构的一个因素。其中一种行为是补偿反应：宿主可以补偿寄生虫损失效应，改变繁殖努力以增强适应度。雌性阿根廷古猿被收集起来并根据其胚胎的发育程度分为两组：新产生的胚胎和准备孵化的胚胎。确定每个雌性的胚胎数量和它们的干重。检查女性身体的所有部位是否有寄生虫。的女性P. argentinus被寄生了小鱼. 我们发现寄生的雌性产生更多的胚胎，但在发育过程中卵子丢失更多，并且寄生的雌性胚胎丢失的百分比高于未寄生的雌性。被寄生的雌性产生的卵比未感染的雌性更轻。这支持了针对该物种提出的补偿性繁殖假设。寄生可以以一种可以补偿繁殖力的方式改变生活史特征；宿主和寄生虫之间的这种共同进化将取决于种群或环境。寄生虫是任何生态系统的功能部分，正如我们的结果所示，删除生活史特征中的寄生虫和在自由生物体中进行的繁殖研究可能会导致对自然界中发生的真实过程的不完整描述。