Priority effect theory, a foundational concept from community ecology, states that the order and timing of species arrival during species assembly can affect species composition. Although this theory has been applied to co-infecting parasite species, it has almost always been with a single time lag between co-infecting parasites. Thus, how the timing of parasite species arrival affects co-infections and disease remains poorly understood. To address this gap in the literature, we exposed post-metamorphic Cuban tree frogs (Osteopilus septentrionalis) to Ranavirus, the fungus Batrachochytrium dendrobatidis (Bd), a nematode Aplectana hamatospicula, or pairs of these parasites either simultaneously or sequentially at a range of time lags and quantified load of the secondary parasite and host growth, survival and parasite tolerance. Prior exposure to Bd or A. hamatospicula significantly increased viral loads relative to hosts singly infected with Ranavirus, whereas A. hamatospicula loads in hosts were higher when co-exposed to Bd than when co-exposed to Ranavirus. There was a significant positive relationship between time since Ranavirus infection and Bd load, and prior exposure to A. hamatospicula decreased Bd loads compared to simultaneous co-infection with these parasites. Infections with Bd and Ranavirus either singly or in co-infections decreased host growth and survival. This research reveals that time lags between co-infections can affect parasite loads, in line with priority effects theory. As co-infections in the field are unlikely to be simultaneous, an understanding of when co-infections are impacted by time lags between parasite exposures may play a major role in controlling problematic co-infections.

中文翻译：

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群落生态学理论在野生动物宿主共感染中的应用

优先效应理论是群落生态学的一个基本概念，它指出物种组装期间物种到达的顺序和时间会影响物种组成。尽管这一理论已被应用于共同感染寄生虫物种，但它几乎总是在共同感染寄生虫之间存在一个时间差。因此，寄生虫物种到达的时间如何影响共同感染和疾病仍然知之甚少。为了解决文献中的这一空白，我们将变质后的古巴树蛙（Osteopilus septentrionalis）暴露于蛙病毒、真菌 Batrachochytrium dendrobatidis (Bd)、线虫 Alectana hamatospicula 或这些寄生虫成对的同时或顺序在一定时间范围内次生寄生虫和宿主生长、存活和寄生虫耐受性的滞后和量化负荷。相对于单独感染 Ranavirus 的宿主，先前暴露于 Bd 或 A. hamatospicula 显着增加了病毒载量，而当共同暴露于 Bd 时，宿主中的 A. hamatospicula 载量高于共同暴露于 Ranavirus 时。自 Ranavirus 感染以来的时间与 Bd 负荷之间存在显着的正相关关系，与同时感染这些寄生虫相比，先前接触 A. hamatospicula 会降低 Bd 负荷。Bd 和 Ranavirus 单独感染或合并感染会降低宿主的生长和存活。这项研究表明，与优先效应理论一致，合并感染之间的时间滞后会影响寄生虫负载。由于现场的合并感染不太可能同时发生，