Phylosymbiosis is an association between host-associated microbiome composition and host phylogeny. This pattern can arise via evolution of host traits, habitat preferences, diets, and co-diversification of hosts and microbes. Understanding the drivers of phylosymbiosis is vital for modelling disease-microbiome interactions and manipulating microbiomes in multi-host systems. This study quantifies phylosymbiosis in Appalachian salamander skin in the context of infection by the fungal pathogen Batrachochytrium dendrobatidis (Bd), while accounting for environmental microbiome exposure. We sampled ten salamander species representing >150 M years divergence, assessed their Bd infection status, and analysed their skin and environmental microbiomes. Our results reveal a significant signal of phylosymbiosis, whereas the local environmental pool of microbes, climate, geography, and Bd infection load had a smaller impact. Host-microbe co-speciation was not evident, indicating that the effect stems from the evolution of host traits influencing microbiome assembly. Bd infection correlated with host phylogeny and the abundance of Bd-inhibitory bacterial strains, suggesting that the long-term evolutionary dynamics between salamander hosts and their skin microbiomes affects the present-day distribution of the pathogen, alongside habitat-linked exposure risk. Five Bd-inhibitory bacterial strains showed unusual generalism: occurring on most host species and habitats. These generalist strains may enhance the likelihood of probiotic manipulations colonising and persisting on hosts. Our results underscore the substantial influence of host-microbiome eco-evolutionary dynamics on environmental health and disease outcomes.

中文翻译：

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系统共生塑造阿巴拉契亚蝾螈的皮肤细菌群落和病原体保护功能


系统共生是宿主相关微生物组组成与宿主系统发育之间的关联。这种模式可以通过宿主特征、栖息地偏好、饮食以及宿主和微生物的共同多样化的进化而产生。了解系统共生的驱动因素对于建模疾病-微生物组相互作用和操纵多宿主系统中的微生物组至关重要。这项研究量化了阿巴拉契亚蝾螈皮肤在真菌病原体 Batrachochytrium dendrobatidis (Bd) 感染的情况下的系统共生，同时考虑了环境微生物组的暴露。我们对代表 >150 M 年差异的 10 种蝾螈进行了采样，评估了它们的 Bd 感染状况，并分析了它们的皮肤和环境微生物组。我们的结果揭示了系统共生的重要信号，而当地微生物环境池、气候、地理和 Bd 感染负荷的影响较小。宿主-微生物共物种并不明显，表明这种效应源于影响微生物组组装的宿主性状的进化。 Bd 感染与宿主系统发育和 Bd 抑制菌株的丰度相关，这表明蝾螈宿主及其皮肤微生物组之间的长期进化动态影响病原体的当前分布，以及与栖息地相关的暴露风险。五种 Bd 抑制菌株表现出不同寻常的普遍性：出现在大多数宿主物种和栖息地。这些通才菌株可能会增加益生菌在宿主体内定殖和持续存在的可能性。我们的结果强调了宿主微生物组生态进化动态对环境健康和疾病结果的重大影响。