Data associated with the manuscript entitled "Amoebozoan testate amoebae illuminate the diversity of heterotrophs and the complexity of ecosystems throughout geological time"

Heterotrophic protists are vital in Earth’s ecosystems, influencing carbon and nutrient cycles and occupying key positions in food webs as microbial predators. Fossils and molecular data suggest the emergence of predatory microeukaryotes and the transition to a eukaryote-rich marine environment by 800 million years ago (Ma). Neoproterozoic vase-shaped microfossils (VSMs) linked to Arcellinida testate amoebae represent the oldest evidence of heterotrophic microeukaryotes. This study explores the phylogenetic relationship and divergence times of modern Arcellinida and related taxa using a relaxed molecular clock approach. We estimate the origin of nodes leading to extant members of the Arcellinida Order to have happened during the latest Mesoproterozoic and Neoproterozoic (1054 - 661 Ma), while the divergence of extant infraorders postdates the Silurian. Our results demonstrate that at least one major heterotrophic eukaryote lineage originated during the Neoproterozoic. A putative radiation of eukaryotic groups (e.g. Arcellinida) during the early-Neoproterozoic sustained by favorable ecological and environmental conditions may have contributed to eukaryotic life endurance during the Cryogenian severe ice ages. Moreover, we infer that Arcellinida most likely already inhabited terrestrial habitats during the Neoproterozoic, coexisting with terrestrial Fungi and green algae, before land plant radiation. The most recent extant Arcellinida groups diverged during the Silurian Period, alongside other taxa within Fungi and flowering plants. These findings shed light on heterotrophic microeukaryotes' evolutionary history and ecological significance in Earth's ecosystems, using testate amoebae as a proxy.

异养原生生物（heterotrophic protists）是地球生态系统的关键类群，它们参与调控碳与营养循环，并作为微生物捕食者在食物网中占据核心生态位。化石与分子数据显示，捕食性微真核生物的出现以及真核生物富集的海洋环境的形成，可追溯至8亿年前（Ma）。与有壳变形虫目（Arcellinida testate amoebae）相关的新元古代（Neoproterozoic）瓶形微化石（vase-shaped microfossils, VSMs），是目前已知最古老的异养微真核生物化石记录。本研究采用宽松分子钟方法（relaxed molecular clock approach），探究了现代有壳变形虫目及其近缘类群的系统发育关系与分化时间。研究估算显示，现生有壳变形虫目类群的起源节点形成于中元古代（Mesoproterozoic）晚期至新元古代（Neoproterozoic）（1054 ~ 661 Ma），而现生亚目的分化时间则晚于志留纪（Silurian）。研究结果表明，至少有一支主要的异养真核生物演化支起源于新元古代（Neoproterozoic）。新元古代（Neoproterozoic）早期，在有利的生态与环境条件支撑下，包括有壳变形虫目在内的真核生物类群可能经历了推测的辐射演化，这一过程或助力真核生物在成冰纪（Cryogenian）的极端冰期得以存续。此外，本研究推断，有壳变形虫目最晚在新元古代（Neoproterozoic）便已占据陆地生境，在陆地植物辐射演化之前，便已与陆生真菌、绿藻共存。最晚分化的现生有壳变形虫类群与真菌、开花植物中的其他类群一样，均在志留纪（Silurian）发生分化。本研究以有壳变形虫作为研究替代类群，阐明了异养微真核生物的演化历史及其在地球生态系统中的生态意义。