Roznik Elizabeth A, Surbaugh Kerri L, Cano Natalia, Rohr Jason R
Department of Integrative Biology, University of South Florida, Tampa, Florida 33620, USA.
Department of Conservation and Research, Memphis Zoo, Memphis, Tennessee 38112, USA.
J Appl Ecol. 2020 Jun;57(6):1078-1088. doi: 10.1111/1365-2664.13634. Epub 2020 Apr 9.
Identifying the mechanisms underlying biological invasions can inform the management of invasive species. The enemy release hypothesis (ERH) suggests that invasive species have a competitive advantage in their introduced range because they leave behind many of their predators and parasites from their native range, allowing them to shift resources from defenses to growth, reproduction, and dispersal. Many studies have demonstrated that invasive species have fewer parasites than their native counterparts, but few studies have tested whether the loss of these natural enemies appears to be a primary driver of the invasion process.To test the ERH, we conducted a mark-recapture study in which we used an anthelmintic drug to successfully reduce parasitic worms in invasive Cuban treefrogs () and native treefrogs ( spp.) at half of 12 wetlands, marking nearly 4,200 frogs. If the ERH is supported, we would expect that treating for parasitic worms would have a greater benefit to native than invasive hosts.Growth and survival rates of invasive and native treefrogs responded similarly to the anthelmintic treatment, suggesting that the Cuban treefrog's release from parasitic worms does not appear to significantly contribute to its invasiveness in established areas. Instead, it appears that the overall faster rates of growth and maturation, higher survival rates, and larger body sizes of Cuban treefrogs that we observed may contribute to their expansion and proliferation.. Although Cuban treefrogs have a lower diversity of parasitic worms in their invasive than native range, this does not appear to significantly contribute to their invasion success in areas where they have been established for more than 20 years. This suggests that any manipulation of parasites in invasive or native hosts would not be an effective method of controlling Cuban treefrogs or reducing their impacts. Further research into other hypotheses is needed to explain the Cuban treefrog's success and help guide management actions to reduce their spread and negative impacts. Our study demonstrates that enemy release may not be a primary driver of invasiveness, highlighting the need for more experimental tests of the enemy release hypothesis to examine its generality.
识别生物入侵背后的机制有助于对外来入侵物种进行管理。天敌释放假说（ERH）认为，外来入侵物种在引入地具有竞争优势，因为它们摆脱了许多来自原生地的捕食者和寄生虫，从而能够将资源从防御转移到生长、繁殖和扩散上。许多研究表明，外来入侵物种的寄生虫比其原生同类少，但很少有研究检验这些天敌的丧失是否似乎是入侵过程的主要驱动因素。为了检验天敌释放假说，我们进行了一项标记重捕研究，在12个湿地中的一半，我们使用驱虫药成功减少了入侵的古巴树蛙（ ）和本地树蛙（ 属物种）体内的寄生虫，标记了近4200只青蛙。如果天敌释放假说得到支持，我们预计驱虫处理对本地宿主的益处会大于入侵宿主。入侵和本地树蛙的生长和存活率对驱虫处理的反应相似，这表明古巴树蛙摆脱寄生虫似乎并没有显著促进其在已建立区域的入侵性。相反，我们观察到的古巴树蛙总体上更快的生长和成熟速度、更高的存活率以及更大的体型可能有助于它们的扩张和繁殖。尽管古巴树蛙在入侵地的寄生虫多样性低于原生地，但这似乎并没有显著促进它们在已建立超过20年的地区的入侵成功。这表明，对外来或本地宿主的寄生虫进行任何操控都不是控制古巴树蛙或减少其影响的有效方法。需要对其他假说进行进一步研究，以解释古巴树蛙的成功，并帮助指导管理行动以减少它们的扩散和负面影响。我们的研究表明，天敌释放可能不是入侵性的主要驱动因素，这凸显了对天敌释放假说进行更多实验测试以检验其普遍性的必要性。
