Altitudinal distribution of chytrid (Batrachochytrium dendrobatidis) infection in subtropical Australian frogs
Altitudinal distribution of chytrid (Batrachochytrium dendrobatidis) infection in subtropical Australian frogs
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DOI：
10.1111/j.1442-9993.2008.01872.x
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发表时间：
2008-12-01
期刊：
影响因子：
1.5
通讯作者：
Hero, Jean-Marc
中科院分区：
文献类型：
--
作者：
Kriger, Kerry M.;Hero, Jean-Marc
在过去的20年里，世界各地看似原始的高地地区两栖动物种群的消失已经成为保护工作的主要焦点，一种寄生的壶菌，树枝状拟青霉，被认为是种群数量下降的原因。我们研究了澳大利亚昆士兰州东南部三种溪流蛙(Litoria wilcoxii、L.pe soniana和L.Chloris)的壶菌感染的海拔分布，并假设如果树蛙是高海拔青蛙种群消失的罪魁祸首，那么感染的流行率和强度将在高海拔地区最大。总体而言，在我们抽样的798只成年青蛙中，有37.7%的青蛙感染了树枝杆菌，我们检查的所有种群都发现了感染。与我们最初的假设相反，我们没有发现一致的证据表明高海拔青蛙比低海拔青蛙更容易感染。此外，高海拔青蛙的真菌感染强度(游动孢子数量)与低海拔青蛙没有显著差异。树突巴氏杆菌似乎能够感染亚热带所有海拔的青蛙，这表明当条件有利于疾病爆发时，所有种群都面临下降的风险。然而，我们确实发现了证据，与低地地区相比，高地地区的壶菌感染持续到夏季的时间更长，这表明山地两栖动物种群比低地种群更容易受到疾病爆发的影响。此外，我们还发现，在高海拔地区，蛙类生长和繁殖的最佳温度与青蛙变态相吻合，而青蛙的变态阶段是青蛙最容易受到壶菌感染的生命阶段。虽然这些海拔高度的差异可能解释了种群水平上对白纹伊蚊的不同反应，但昆士兰东南部许多山地青蛙种群急剧下降而低地种群保持稳定的原因尚未得到解决。
The disappearance of amphibian populations from seemingly pristine upland areas worldwide has become a major focus of conservation efforts in the last two decades, and a parasitic chytrid fungus, Batrachochytrium dendrobatidis, is thought to be the causative agent of the population declines. We examined the altitudinal distribution of chytrid infections in three stream-dwelling frog species (Litoria wilcoxii, L. pearsoniana and L. chloris) in southeast Queensland, Australia, and hypothesized that if B. dendrobatidis were responsible for the disappearance of high-altitude frog populations, infection prevalence and intensity would be greatest at higher altitudes. Overall, 37.7% of the 798 adult frogs we sampled were infected with B. dendrobatidis, and infections were found in all the populations we examined. Contrary to our initial hypothesis, we found no consistent evidence that high-altitude frogs were more likely to be infected than were lowland frogs. Further, the intensity of fungal infections (number of zoospores) on high-altitude frogs did not differ significantly from that of lowland frogs. Batrachochytrium dendrobatidis appears to be capable of infecting frogs at all altitudes in the subtropics, suggesting that all populations are at risk of decline when conditions favour disease outbreaks. We did find evidence, however, that chytrid infections persist longer into summer in upland as compared with lowland areas, suggesting that montane amphibian populations remain susceptible to disease outbreaks for longer periods than do lowland populations. Further, we found that at high altitudes, temperatures optimal for chytrid growth and reproduction coincide with frog metamorphosis, the life-stage at which frogs are most susceptible to chytrid infections. While these altitudinal differences may account for the differential population-level responses to the presence of B. dendrobatidis, the reason why many of southeast Queensland's montane frog populations declined precipitously while lowland populations remained stable has yet to be resolved.