EAPSI: Adapting to Life with Less Water: Immune Function of Cane Toads in Semi-Arid Australia

入侵甘蔗蟾蜍（Rhinella marina）自1935年首次引入澳大利亚以来，一直在扩大其范围。它们固有的毒性导致了数十种本地物种的急剧种群崩溃。根据其原生栖息地的温度和水分特征，人们认为它们的入侵将仅限于澳大利亚的热带地区。然而，它们的入侵正在迅速扩大，超出了假定的限度，这可能是逐步适应干旱条件的结果。如果甘蔗蟾蜍能够迅速进化到新的气候条件，那么它们的范围扩张可能会远远超出以前认为的限制，从而威胁到大陆的更大部分。通过结合实地和实验室研究，该项目将侧重于免疫系统，以评估甘蔗蟾蜍的适应性，通过测试的假设，甘蔗蟾蜍在干旱入侵前线适应耐受水分限制，以保持有效的免疫功能。该项目将与澳大利亚悉尼大学著名的爬行动物和两栖动物生态学专家Rick Shine博士合作进行。 该项目将采用生态免疫学方法评估甘蔗蟾蜍在澳大利亚的分布潜力。这项研究将比较自然发生的水化状态和免疫性能的蟾蜍从干旱入侵前线的那些从梅西奇范围核心。这些结果将得到一项实验室研究的补充，该研究将通过实验方式操纵这两个地点动物的水合状态，以确定与在澳大利亚的蟾蜍中发现的蟾蜍相比，来自澳大利亚半干旱地区的蟾蜍在脱水时是否会受到更少的抑制甚至增强免疫功能。首次引入澳大利亚的中温地区。这些实验的结果将改变这种入侵物种以及其他可能的入侵物种的分布预测方式。东亚和太平洋夏季研究所计划下的这个奖项支持美国研究生的夏季研究，由NSF和澳大利亚科学院共同资助。

Invasive cane toads (Rhinella marina) in Australia have been expanding their range since they were first introduced in 1935. Their inherent toxicity has resulted in dramatic population crashes of dozens of native species. Based on temperature and water characteristics of their native habitats, it was assumed their invasion would be restricted to tropical areas of Australia. However, their invasion is rapidly expanding beyond the presumed limits, and this may be a result of progressive adaptation to drier conditions. If cane toads can rapidly evolve to new climatic conditions, then their range expansion might exceed well beyond previously thought limitations and thus threaten a greater portion of the continent. Through a combination of field and laboratory studies, this project will focus on the immune system to evaluate the adaptability of cane toads by testing the hypothesis that cane toads at the dry invasion front are adapting a tolerance to water limitations in order to maintain effective immune function. This project will be conducted in collaboration with Dr. Rick Shine, a noted expert on the ecology of reptiles and amphibians, at the University of Sydney, Australia. This project will take an ecoimmunological approach to assess the distribution potential of cane toads in Australia. This study will compare naturally occurring hydration states and immune performances of toads from the arid invasion front with those from the mesic range core. These results will be complemented by a laboratory study that will experimentally manipulate the hydration state of animals from both sites to determine whether toads from semi-arid portions of Australia will have less suppressed or even enhanced immune function when dehydrated compared to toads found in more mesic areas of Australia where they were first introduced. The results of these experiments would transform the way distributions are predicted for this, and likely other, invasive species. This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the Australian Academy of Science.