Data from: Allee effects may slow the spread of parasites in a coastal marine ecosystem

Allee effects are thought to mediate the dynamics of population colonization, particularly for invasive species. However, Allee effects acting on parasites have rarely been considered in the analogous process of infectious disease establishment and spread. We studied the colonization of uninfected wild juvenile Pacific salmon populations by ectoparasitic salmon lice (Lepeophtheirus salmonis) over four years. From a dataset of 67,896 fish, we observed 88 occurrences of pre-copular pair formation among 1258 pre-adult female and 611 adult male lice. The probability of pair formation was dependent on the local abundance of lice, but this mate limitation is likely offset somewhat by mate-searching dispersal of males among host fish. A mathematical model of macroparasite population dynamics that incorporates the empirical results suggests a high likelihood of a demographic Allee effect, which can cause the colonizing parasite populations to die out. These results may provide the first empirical evidence for Allee effects in a macroparasite. Furthermore, the data give a rare detailed view of Allee effects in colonization dynamics and suggest that Allee effects may dampen the spread of parasites in a coastal marine ecosystem.阿利效应（Allee effect）被认为可调控种群定殖的动态过程，对于入侵物种而言尤为如此。然而，在传染病建立与传播的同类过程中，针对寄生虫的阿利效应却鲜有被纳入考量范畴。 我们针对四年间体外寄生鲑鱼虱（Lepeophtheirus salmonis）定殖未受感染的野生幼年太平洋鲑鱼种群的过程展开研究。基于涵盖67896尾鱼类的数据集，我们在1258只预成虫雌性鲑鱼虱与611只成虫雄性鲑鱼虱中，观测到88次交配前配对行为。 交配配对的发生概率与宿主体表虱子的局部丰度密切相关，但雄性个体在宿主鱼类间开展的交配搜寻扩散行为，或可在一定程度上缓解这一配偶限制效应。 整合本次实证结果的大型寄生虫（macroparasite）种群动态数学模型显示，种群统计阿利效应（demographic Allee effect）出现的可能性极高，该效应可致使定殖的寄生虫种群走向灭绝。 本研究结果或可为大型寄生虫类群中的阿利效应提供首个实证依据。此外，本次数据集提供了极为罕见且详尽的定殖动态阿利效应观测视角，同时表明阿利效应或可抑制沿海海洋生态系统中寄生虫的传播扩散。