Climatically extreme regions such as the polar deserts of the McMurdo Dry Valleys (78° S) in Continental Antarctica are key areas for a better understanding of changes in ecosystems. Therefore, it is particularly important to analyze and communicate current patterns of biodiversity in these sensitive areas, where precipitation mostly occurs in form of snow and liquid water is rare. Humidity provided by dew, clouds, and fog are the main water sources, especially for rock-dwelling crustose lichens as one of the most common vegetation-forming organisms. We investigated the diversity and interaction specificity of myco-/photobiont associations of 232 crustose lichen specimens, collected along an elevational gradient (171–959 m a.s.l.) within the McMurdo Dry Valleys. The mycobiont species and photobiont OTUs were identified by using three markers each (nrITS, mtSSU, RPB1, and nrITS, psbJ-L, COX2). Elevation, positively associated with water availability, turned out to be the key factor explaining most of the distribution patterns of the mycobionts. Pairwise comparisons showed Lecidea cancriformis and Rhizoplaca macleanii to be significantly more common at higher elevations and Carbonea vorticosa and Lecidea polypycnidophora at lower elevations. Lichen photobionts were dominated by the globally distributed Trebouxia OTU, Tr_A02 which occurred at all habitats. Network specialization resulting from myco-/photobiont bipartite network structure varied with elevation and associated abiotic factors. Along an elevational gradient, the spatial distribution, diversity, and genetic variability of the lichen symbionts appear to be mainly influenced by improved water relations at higher altitudes.

中文翻译：

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麦克默多干谷（南极洲）的甲壳质地衣中的真菌和光生物关联揭示了沿海拔梯度的高度分化

气候极端地区，例如南极大陆麦克默多干谷（南纬 78°）的极地沙漠，是更好地了解生态系统变化的关键区域。因此，分析和交流这些敏感地区当前的生物多样性模式尤为重要，这些地区的降水主要以雪的形式出现，液态水很少见。露水、云和雾提供的湿度是主要的水源，特别是对于岩栖地衣作为最常见的植被形成生物之一。我们调查了沿麦克默多干谷内海拔梯度 (171–959 m asl) 收集的 232 个甲壳类地衣标本的真菌-/光生物关联的多样性和相互作用特异性。真菌生物物种和光生物 OTU 分别通过使用三个标记（nrITS、mtSSU、RPB1 和 nrITS、psbJ-L、COX2）来识别。海拔与可用水量呈正相关，结果证明是解释大多数分枝杆菌分布模式的关键因素。成对比较显示 Lecidea cancriformis 和 Rhizoplaca macleanii 在高海拔地区更常见，而 Carbonea vorticosa 和 Lecidea polypycnidophora 在低海拔地区更常见。地衣光生物以全球分布的 Trebouxia OTU Tr_A02 为主，其发生在所有栖息地。由真菌/光生物二分网络结构导致的网络专业化随海拔高度和相关非生物因素而变化。沿着海拔梯度，空间分布、多样性、