Data_Sheet_1_Gullies and Moraines Are Islands of Biodiversity in an Arid, Mountain Landscape, Asgard Range, Antarctica.docx

Cold, dry, and nutrient-poor, the McMurdo Dry Valleys of Antarctica are among the most extreme terrestrial environments on Earth. Numerous studies have described microbial communities of low elevation soils and streams below glaciers, while less is known about microbial communities in higher elevation soils above glaciers. We characterized microbial life in four landscape features (habitats) of a mountain in Taylor Valley. These habitats varied significantly in soil moisture and include moist soils of a (1) lateral glacial moraine, (2) gully that terminates at the moraine, and very dry soils on (3) a southeastern slope and (4) dry sites near the gully. Using rRNA gene PCR amplicon sequencing of Bacteria and Archaea (16S SSU) and eukaryotes (18S SSU), we found that all habitat types harbored significantly different bacterial and eukaryotic communities and that these differences were most apparent when comparing habitats that had macroscopically visible soil crusts (gully and moraine) to habitats with no visible crusts (near gully and slope). These differences were driven by a relative predominance of Actinobacteria and a Colpodella sp. in non-crust habitats, and by phototrophic bacteria and eukaryotes (e.g., a moss) and predators (e.g., tardigrades) in habitats with biological soil crusts (gully and moraine). The gully and moraine also had significantly higher 16S and 18S ESV richness than the other two habitat types. We further found that many of the phototrophic bacteria and eukaryotes of the gully and moraine share high sequence identity with phototrophs from moist and wet areas elsewhere in the Dry Valleys and other cold desert ecosystems. These include a Moss (Bryum sp.), several algae (e.g., a Chlorococcum sp.) and cyanobacteria (e.g., Nostoc and Phormidium spp.). Overall, the results reported here broaden the diversity of habitat types that have been studied in the Dry Valleys of Antarctica and suggest future avenues of research to more definitively understand the biogeography and factors controlling microbial diversity in this unique ecosystem.

南极洲的麦克默多干燥谷地，气候寒冷、干燥且营养贫乏，堪称地球上最极端的陆地环境之一。众多研究已描述了冰川下方低海拔土壤和溪流的微生物群落，而对于冰川上方高海拔土壤中的微生物群落，了解则相对较少。我们对泰勒谷山脉上的四个景观特征（栖息地）中的微生物生命进行了特征描述。这些栖息地在土壤湿度上存在显著差异，包括（1）侧向冰川漂砾的湿润土壤，（2）以冰川漂砾为终点的沟壑，以及（3）东南坡和（4）沟壑附近的干燥地点。通过细菌和古菌（16S SSU）以及真核生物（18S SSU）的rRNA基因PCR扩增子测序，我们发现所有栖息地类型均含有显著不同的细菌和真核生物群落，并且这些差异在比较具有宏观可见土壤皮壳的栖息地（沟壑和漂砾）与无可见皮壳的栖息地（沟壑附近和坡地）时最为明显。这些差异主要由非皮壳栖息地中放线菌和Colpodella属的相对优势，以及具有生物土壤皮壳的栖息地（沟壑和漂砾）中的光合细菌和真核生物（例如，苔藓）以及捕食者（例如，缓步动物）所驱动。沟壑和漂砾的16S和18S ESV丰富度也显著高于其他两种栖息地类型。此外，我们还发现沟壑和漂砾中的许多光合细菌和真核生物与干燥谷地其他湿润和潮湿地区的光合生物以及其他寒冷沙漠生态系统的光合生物具有较高的序列相似性。这些包括苔藓（Bryum属）、几种藻类（例如，Chlorococcum属）和蓝藻（例如，Nostoc和Phormidium属）。总体而言，本研究报告扩展了南极洲干燥谷地中已研究的栖息地类型多样性，并为进一步深入研究该独特生态系统的生物地理学以及控制微生物多样性的因素提供了新的研究方向。