Department of Biological Sciences, Purdue University, 915 Mitch Daniels Blvd, West Lafayette, IN, 47907, USA.
Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, 15260, USA.
Oecologia. 2024 Feb;204(2):327-337. doi: 10.1007/s00442-023-05444-4. Epub 2023 Aug 24.
Invasive species can have large effects on native communities. When native and invasive species share parasites, an epidemic in a native species could facilitate or inhibit the invasion. We sought to understand how the incidence and timing of epidemics in native species caused by a generalist parasite influenced the success and impact of an invasive species. We focused on North American native and invasive species of zooplankton (Daphnia dentifera and Daphnia lumholtzi, respectively), that can both become infected with a fungal parasite (Metschnikowia bicuspidata). In a laboratory microcosm experiment, we exposed the native species to varying parasite inocula (none, low, high) and two invasive species introduction times (before or during an epidemic in the native species). We found that the invasive species density in treatments with the parasite was higher compared to uninfected treatments, though only the early invasion, low-parasite and uninfected treatments exhibited significant pairwise differences. However, invasive resting eggs were only found in the uninfected treatments. The density of the native species was lowest with a combination of the parasite present, and the invasive species introduced during the epidemic. Native infection prevalence in these treatments (late invasion, parasite present) was also higher than prevalence in treatments where the invasive species was introduced before the epidemic. Therefore, the timing of an invasion relative to an epidemic can affect both the native and invasive species. Our results suggest that the occurrence and timing of epidemics in native species can influence the impacts of a species invasion.
入侵物种会对本地群落产生重大影响。当本地物种和入侵物种共享寄生虫时，本地物种的流行病可能会促进或抑制入侵。我们试图了解由一种寄生虫引起的本地物种流行病的发生和时间如何影响入侵物种的成功和影响。我们关注的是北美本地和入侵的浮游动物物种（分别为 Daphnia dentifera 和 Daphnia lumholtzi），它们都可能感染一种真菌寄生虫（Metschnikowia bicuspidata）。在实验室微宇宙实验中，我们将本地物种暴露于不同的寄生虫接种物（无、低、高）和两种入侵物种引入时间（在本地物种流行病之前或期间）。我们发现，在有寄生虫的处理中，入侵物种的密度高于未感染的处理，尽管只有早期入侵、低寄生虫和未感染的处理表现出显著的成对差异。然而，未感染的处理中只发现了入侵物种的休眠卵。在有寄生虫存在且入侵物种在流行病期间引入的情况下，本地物种的密度最低。在这些处理中（后期入侵，有寄生虫存在），本地物种的感染流行率也高于在流行病之前引入入侵物种的处理。因此，入侵相对于流行病的时间可以影响本地和入侵物种。我们的结果表明，本地物种流行病的发生和时间可能会影响物种入侵的影响。
