Are glacier surfaces the last refuge of an evolutionarily ancient lineage of unknown fungi?

冰川和冰盖越来越被认为是令人惊讶的多样化和活跃的微生物生态系统的家园。即使是在与世隔绝了数千年的南极冰下湖泊中生活的前景，也吸引了国际上的主要关注和投资。然而，由于生命肯定在冰川表面不寻常的栖息地繁衍生息。在我们探索微生物生物多样性的尝试中，这些都不应被忽视。冻石洞就是这样一个栖息地，当岩石尘埃被一个多样化和高度活跃的微生物联盟殖民时，形成了一个黑暗的微生物-矿物质聚集体，增加了太阳能量到冰的转移，从而加速了表面的融化。我的博士研究重点是冰晶石细菌群落的多样性和功能，该群落由与世界各地广泛栖息地的分类群密切相关的生物主导。与之形成鲜明对比的是，在北极高寒冰川上的真核生物中，生物量最丰富的真菌类群似乎主要由两类迄今未知的相关真菌组成。在从斯瓦尔巴群岛冷锥体提取的真菌DNA集合中，这些真菌占75%的序列，根据使用该组特有基因染色的显微镜，这些真菌来自附着在碎片上的小卵形细胞。对真菌进行的特定DNA测试的测序结果表明，它们存在于世界各地的冷锥石中，这表明它们存在于广泛的地理范围内，而DNA数据库中没有附属序列，以及未能在冰缘生境中检测到这一组，这意味着它们仅限于真菌生命树根部附近的冷锥岩群，并提供了新元古代的粗略估计的分歧，新元古代由主要的世界范围的冰川组成，包括假想的“雪球地球”。人们对这些暂时命名为“低温真菌”的真菌知之甚少。因此，我寻求支持，详细说明它们的进化史、种群结构、生态功能和相互作用。这样做将允许检验以下假设：i)“低温菌类”在现存的低温菌类生态系统的功能中发挥重要作用；ii)它们形成真菌生命树上的一个主要新分支；iii)低温菌类洞穴在冰川周期中为这些真菌形成了一个稳定的避难所。因此，我期待着对冰锥体生物多样性和冰川融化之间相互作用的洞察，无论是在当今，还是在假设的从新元古代“雪球”到“泥球”地球的假设过渡中。

Glaciers and ice-sheets are increasingly recognized as the homes of surprisingly diverse and active microbial ecosystems. Even the mere prospect of life in Antarctic subglacial lakes, isolated for many millennia, attracts major international attention and investment. However since life certainly flourishes in unusual habitats on glacier surfaces. these should not be overlooked in our attempts to explore microbial biodiversity. Cryoconite holes are one such habitat, formed when rocky dusts are colonized by a diverse and highly active microbial consortium, forming a darkened microbe-mineral aggregate which increases the transfer of the sun's energy to ice and thus accelerates surface melt. My doctoral studies centred on the diversity and functioning of the bacterial community of cryoconite, which is dominated by organisms closely related to taxa in a broad range of habitats world-wide. In stark contrast, of the eukaryotes inhabiting cryoconite on High Arctic glaciers, the most abundant group by biomass, Fungi, appears strongly dominated by two related groups of fungi hitherto unknown to science. These fungi account for 75% of the sequences in collections of fungal DNA extracted from Svalbard cryoconite, and according to microscopy using genetic stains specific to the group, are derived from small ovoid cells attached to debris. Sequenced genes from specific DNA tests for the fungi demonstrate their presence in cryoconite worldwide suggesting a broad geographic range while the absence of affiliated sequences from DNA databases and the failure to detect the group in periglacial habitats imply their restriction to the cryoconite group near the root of the fungal tree of life and provide a crudely estimated divergence during the Neoproterozoic era, which consisted of major world-wide glaciations, including a hypothesized "Snowball Earth". Little else is known about these fungi, tentatively named the "cryomycetes". Therefore, I seek support to detail their evolutionary history, population structure, ecological functions and interactions. Doing so will permit the testing of the hypotheses that i)"cryomycetes" assume a significant role in the functioning of the extant cryoconite ecosystem ii)they form a major new branch on the fungal tree of life iii)cryoconite holes have formed a stable refuge for these fungi over glacial cycles. As a consequence, I anticipate insights into the interactions between cryoconite biodiversity and melting glaciers, both in the present day, and potentially in the postulated transition from a Neoproterozoic "Snowball" to a "Mudball" Earth.