Institute for the Environment, Florida International University Miami, FL 33199, USA.
Department of Biology, Georgia Southern University, Statesboro, GA 30458, USA.
Biol Lett. 2020 Aug;16(8):20200474. doi: 10.1098/rsbl.2020.0474. Epub 2020 Aug 5.
Introduced species can become invasive, damaging ecosystems and disrupting economies through explosive population growth. One mechanism underlying population expansion in invasive populations is 'enemy release', whereby the invader experiences relaxation of agonistic interactions with other species, including parasites. However, direct observational evidence of release from parasitism during invasion is rare. We mimicked the early stages of invasion by experimentally translocating populations of mite-parasitized slender anole lizards () to islands that varied in the number of native anoles. Two islands were anole-free prior to the introduction, whereas a third island had a resident population of Gaige's anole (). We then characterized changes in trombiculid mite parasitism over multiple generations post-introduction. We found that mites rapidly went extinct on one-species islands, but that lizards introduced to the two-species island retained mites. After three generations, the two-species island had the highest total density and biomass of lizards, but the lowest density of the introduced species, implying that the 'invasion' had been less successful. This field-transplant study suggests that native species can be 'enemy reservoirs' that facilitate co-colonization of ectoparasites with the invasive host. Broadly, these results indicate that the presence of intact and diverse native communities may help to curb invasiveness.
引入物种可能会成为入侵物种，通过爆炸性的种群增长破坏生态系统和扰乱经济。入侵种群中种群扩张的一个机制是“天敌释放”，即入侵者与其他物种（包括寄生虫）的竞争相互作用减弱。然而，入侵过程中寄生虫释放的直接观察证据很少。我们通过实验将寄生螨虫的细长蜥蜴种群（）转移到不同数量本地蜥蜴的岛屿上来模拟入侵的早期阶段。在引入之前，有两个岛屿没有蜥蜴，而第三个岛屿有盖格蜥蜴（）的本地种群。然后，我们描述了引入后多个世代中跳虫寄生的变化。我们发现，螨虫在单一种群的岛屿上迅速灭绝，而引入到两种群岛屿的蜥蜴则保留了螨虫。三代后，两种群岛屿的蜥蜴总密度和生物量最高，但引入物种的密度最低，这意味着“入侵”不太成功。这项野外移植研究表明，本地物种可能是“天敌库”，有利于外来寄生虫与入侵宿主的共同定殖。从广义上讲，这些结果表明，完整和多样化的本地群落的存在可能有助于抑制入侵性。
