Emerging infectious diseases can cause dramatic declines in wildlife populations. Sometimes, these declines are followed by recovery, but many populations do not recover. Studying differential recovery patterns may yield important information for managing disease-afflicted populations and facilitating population recoveries. In the late 1980s, a chytridiomycosis outbreak caused multiple frog species in Australia’s Wet Tropics to decline. Populations of some species (e.g., Litoria nannotis ) subsequently recovered, while others (e.g., Litoria dayi ) did not. We examined the population genetics and current infection status of L. dayi , to test several hypotheses regarding the failure of its populations to recover: (1) a lack of individual dispersal abilities has prevented recolonization of previously occupied locations, (2) a loss of genetic variation has resulted in limited adaptive potential, and (3) L. dayi is currently adapting to chytridiomycosis. We found moderate-to-high levels of gene flow and diversity ( Fst range: <0.01–0.15; minor allele frequency (MAF): 0.192–0.245), which were similar to previously published levels for recovered L. nannotis populations. This suggests that dispersal ability and genetic diversity do not limit the ability of L. dayi to recolonize upland sites. Further, infection intensity and prevalence increased with elevation, suggesting that chytridiomycosis is still limiting the elevational range of L. dayi . Outlier tests comparing infected and uninfected individuals consistently identified 18 markers as putatively under selection, and several of those markers matched genes that were previously implicated in infection. This suggests that L. dayi has genetic variation for genes that affect infection dynamics and may be undergoing adaptation.

中文翻译：

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感染动态、传播和适应：了解疾病爆发后残余青蛙种群缺乏恢复

新出现的传染病会导致野生动物种群数量急剧下降。有时，这些下降之后是恢复，但许多人口没有恢复。研究不同的恢复模式可能会为管理受疾病影响的人群和促进人口恢复提供重要信息。在 1980 年代后期，壶菌病的爆发导致澳大利亚湿热带地区的多种青蛙物种数量减少。一些物种（例如 Litoria nannotis ）的种群随后恢复，而其他物种（例如 Litoria dayi ）则没有。我们检查了 L. dayi 的种群遗传学和当前感染状况，以检验有关其种群未能恢复的几个假设：（1）缺乏个体分散能力阻止了以前占领的地点的重新殖民，(2) 遗传变异的丧失导致适应潜力有限，(3) L. dayi 目前正在适应壶菌病。我们发现了中等到高水平的基因流动和多样性（Fst 范围：<0.01-0.15；次要等位基因频率（MAF）：0.192-0.245），这与先前公布的恢复的 L. nannotis 种群的水平相似。这表明传播能力和遗传多样性不会限制 L. dayi 重新定居高地的能力。此外，感染强度和流行率随着海拔升高而增加，这表明壶菌病仍然限制了 L. dayi 的海拔范围。比较受感染和未受感染个体的异常值测试一致地将 18 个标记确定为假定处于选择状态，其中一些标记与先前与感染有关的基因相匹配。