Shifts in temperature influence how Batrachochytrium dendrobatidis infects amphibian larvae
Shifts in temperature influence how Batrachochytrium dendrobatidis infects amphibian larvae
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DOI：
10.1371/journal.pone.0222237
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发表时间：
2019-09-19
期刊：
影响因子：
3.7
通讯作者：
Blaustein, Andrew R.
中科院分区：
文献类型：
--
作者：
Bradley, Paul W.;Brawner, Michael D.;Blaustein, Andrew R.
许多气候变化模型预测温度波动的频率和幅度会增加，这可能会影响变温动物受疾病影响的方式。温度的变化可能尤其会影响两栖动物，这些动物的种群受到了多种病原体的挑战。由于两栖动物宿主在较温暖的温度下比在较冷的温度下对免疫力投入更多，并且寄生虫可能比宿主更快地适应温度变化（在最佳宿主免疫力方面造成滞后），因此研究人员假设，从寒冷到温暖的温度转变可能会导致两栖动物对病原体的敏感性增加，而从温暖到寒冷的转变可能会导致敏感性下降。先前对导致两栖动物壶菌病的真菌 Batrachochytrium dendrobatidis (Bd) 的研究为这种基于气候变化的假说提供了支持。我们通过实验测试了暴露于 Batrachochytrium dendrobatidis (Bd) 之前的温度变化是否会改变两种两栖动物——西部蟾蜍 (Anaxyrus boreas) 和北方红腿蛙 (Rana aurora) 幼虫阶段对壶菌病的易感性。与恒定的温暖（20 摄氏度）温度相比，两种宿主物种在恒定的寒冷（15 摄氏度）温度下都具有较高的 Bd 感染强度。此外，与恒定的 20 摄氏度相比，这两个物种在从 15 摄氏度转变为 20 摄氏度后，Bd 感染丰度有所增加，但与恒定的 15 摄氏度相比，从 20 摄氏度转变为 15 摄氏度后，它们的 Bd 感染丰度有所下降。这些结果与之前对成年两栖动物的研究形成鲜明对比，这些研究强调了壶菌病温度依赖性的物种和阶段差异的可能性。
Many climate change models predict increases in frequency and magnitude of temperature fluctuations that might impact how ectotherms are affected by disease. Shifts in temperature might especially affect amphibians, a group with populations that have been challenged by several pathogens. Because amphibian hosts invest more in immunity at warmer than cooler temperatures and parasites might acclimate to temperature shifts faster than hosts (creating lags in optimal host immunity), researchers have hypothesized that a temperature shift from cold-to-warm might result in increased amphibian sensitivity to pathogens, whereas a shift from warm-to-cold might result in decreased sensitivity. Support for components of this climate-variability based hypothesis have been provided by prior studies of the fungus Batrachochytrium dendrobatidis (Bd) that causes the disease chytridiomycosis in amphibians. We experimentally tested whether temperature shifts before exposure to Batrachochytrium dendrobatidis (Bd) alters susceptibility to the disease chytridiomycosis in the larval stage of two amphibian species-western toads (Anaxyrus boreas) and northern red legged frogs (Rana aurora). Both host species harbored elevated Bd infection intensities under constant cold (15 degrees C) temperature in comparison to constant warm (20 degrees C) temperature. Additionally, both species experienced an increase in Bd infection abundance after shifted from 15 degrees C to 20 degrees C, compared to a constant 20 degrees C but they experienced a decrease in Bd after shifted from 20 degrees C to 15 degrees C, compared to a constant 15 degrees C. These results are in contrast to prior studies of adult amphibians highlighting the potential for species and stage differences in the temperature-dependence of chytridiomycosis.