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Mirroring the effect of geological evolution: Protist divergence in the Atacama Desert
Global and Planetary Change ( IF 3.9 ) Pub Date : 2020-07-01 , DOI: 10.1016/j.gloplacha.2020.103193
Hartmut Arndt , Benedikt Ritter , Alexandra Rybarski , Sabine Schiwitza , Tibor Dunai , Frank Nitsche

Abstract Unicellular eukaryotes, also called protists, are potentially fast evolving organisms. The small size of protists, their fast reproduction rate and ability to form cysts as well as their adaptability to extreme conditions allow them to associate to endemic animals, plants, saline lakes and soil even in extremely arid systems. These properties make unicellular eukaryotes ideal model organisms to combine studies on evolutionary processes of very different groups of organisms and across very different time scales comprising even geological ones. The hyperarid Atacama Desert offers a study area unique on Earth, where a predominantly arid climate was present for millions of years. A comprehensive analysis of the diversity of unicellular eukaryotes in different habitats (endemic desert plant phyllosphere, the gut of endemic darkling beetles, isolated hypersaline waters) revealed a dataset distinct and divergent from other regions on Earth. We used standard isolation and cultivation protocols to elucidate divergence patterns for a variety of very different and independent taxonomic groups of protists such as gregarines and ciliates among alveolates, placidids among stramenopiles and choanoflagellates among opisthokonts. The ability to rapidly adapt to extreme environments, which enhance a fast divergence rate at high UV radiation, has only been reported for prokaryotes up to now. The establishment of arid to hyperarid conditions in the Atacama Desert about 20 Ma ago has obviously led to an isolation of protist populations followed by a radiation of species. There are only a few regions on Earth with similar extreme salinity conditions reducing the chance of an exchange between protist populations. Divergence patterns in unicellular eukaryotes in very different phylogenetic groups independently mirror the effect of geological evolution and climate variability during the Neogene.

中文翻译:

反映地质演化的影响:阿塔卡马沙漠中的原生生物分化

摘要 单细胞真核生物,也称为原生生物,是潜在的快速进化生物。原生生物体型小、繁殖速度快、形成囊肿的能力以及对极端条件的适应性,使它们即使在极端干旱的系统中也能与地方性动物、植物、盐湖和土壤联系在一起。这些特性使单细胞真核生物成为理想的模式生物,可以将非常不同的生物群的进化过程研究结合起来,跨越非常不同的时间尺度,甚至包括地质时期。极度干旱的阿塔卡马沙漠提供了一个地球上独一无二的研究区域,那里以干旱为主的气候已经存在了数百万年。对不同生境(地方性沙漠植物叶际、地方性暗甲虫的肠道、孤立的超咸水)揭示了一个与地球上其他地区截然不同的数据集。我们使用标准的分离和培养方案来阐明各种非常不同和独立的原生生物分类群的分化模式,例如肺泡动物中的群落和纤毛虫,原生藻中的 placidids 和 opisthokonts 中的鞭毛藻。迄今为止,仅在原核生物中报道了快速适应极端环境的能力,这增强了高紫外线辐射下的快速发散率。大约 20 Ma 前,阿塔卡马沙漠中干旱到超干旱条件的建立显然导致了原生生物种群的隔离,随后是物种的辐射。地球上只有少数几个地区具有类似的极端盐度条件,从而减少了原生生物种群之间交流的机会。非常不同的系统发育群中单细胞真核生物的分歧模式独立地反映了新近纪期间地质演化和气候变异的影响。
更新日期:2020-07-01
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