Evolution of Morphology and Trophic Strategies in Antarctic Agglutinated Foraminifera

有孔虫是一种结构复杂、数量丰富、分布广泛的原生动物。异形有孔虫经常主宰深海和高纬度的组合，并被认为积极地改造这些栖息地的沉积物。异形线虫在大陆斜坡系统中也很常见，这对有机质的循环非常重要，因此对全球生物地球化学循环也很重要。大多数对有孔虫生物学的研究都集中在热带/温带浅海环境中的物种，在那里它们被证明采用了从渗透营养到后生动物肉食的各种营养策略。作为深海环境中小型和大型底栖动物的主要组成部分，更好地了解底栖异形目动物的就地行为和摄食生物学对海洋科学具有重要意义。目前，南极洲的探险者湾是地球上唯一一个生物学家可以使用水肺直接进入类似深海的生态系统并大量采集基础异形虫的地方；因此，它是一个具有深刻科学价值的地点。勘探者湾有孔洞通常的水深范围可达3 000米，是野外和实验室实验的理想选择，是研究深海组合的生态和演化的有用模式系统。正如对原生生物的确切了解对于建立早期核生物进化的清晰图景至关重要，有孔虫起源的关键在于对早期分枝异形虫的研究。通过基于多基因的分子系统学来更好地理解早期有孔虫之间的关系是这个项目的一个目标。此外，对“树冠异形虫”的更仔细研究将阐明导致轮虫的进化步骤，它们主导着许多浅水温带环境和远洋有孔虫组合。现存的原生生物代表了古代捕食性(食性)原核生物的现代产物。原生生物是众所周知的微生物区系的消费者，但原生生物对后生动物的消耗并没有得到广泛的重视，这是我们对异形线虫研究的重点之一。因此，远古捕食性原生生物的后果很少被认为是晚元古代/早寒武世动物多样性的主要因素。该项目将检验对后生动物的捕食在基底有孔虫中普遍存在的假设，如果得到对新的蛋白质编码序列数据的分析的支持，那么这些原生动物在新元古代生态系统中的作用将需要重新评估。这项研究的目的是：检验目前仅基于单基因序列数据的有孔虫系统发育假说的有效性；检查异形虫支系代表性成员的超微结构；利用新的分子系统发生和结构数据探索极地有孔虫的起源；进一步研究异形虫的营养策略；以及确定肉食性是基孔虫的基本营养模式，还是特殊的衍生特征。这项研究的其他更广泛的影响包括通过基层努力和正式参与国家联邦资助的教育项目来培训代表性不足的群体。

Foraminifera ("forams") are structurally complex, abundant, and widely distributed protists. Allogromiid forams often dominate deep-sea and high-latitude assemblages, and are believed to aggressively rework sediments in these habitats. Allogromiids are also common in continental slope systems, which are important for the recycling of organic matter and hence for global biogeochemical cycles. Most studies of foram biology have focused on species from shallow tropical/temperate settings, where they have been shown to employ diverse trophic strategies ranging from osmotrophy to metazoan carnivory. As a major meio- and macrofaunal component in deeper settings, a better understanding of the in situ behavior and feeding biology of basal allogromiids is of major importance to the ocean sciences. Explorers Cove, Antarctica, is currently the only place on Earth where biologists can use scuba to directly access a "deep-sea-like" ecosystem and collect basal allogromiids in bulk; it is therefore a site of profound scientific interest. Explorers Cove forams, which may normally have bathymetric ranges to 3,000 m, are ideal for field and laboratory experimentation, and serve as useful model systems for studying the ecology and evolution of deep-sea assemblages. Just as a firm understanding of the protists is vital to developing a clear picture of earlyeukaryotic evolution, the key to the origin of Foraminifera lies in the study of the early branching allogromiids. An improved understanding of the relationships between early forams through multigene based molecular phylogenies is a goal of this project. Additionally, a more careful study of the "crown allogromiids" will illuminate the evolutionary steps that lead to the rotaliids, which dominate many shallow-water temperate environments and pelagic foram assemblages. Extant protists represent the modern products of ancient predatory (phagotrophic) prokaryotes. Protists are well known as consumers of microbiota, but the consumption of metazoans by protists, one focus of our studies on allogromiids, is not widely appreciated. As a result, the consequences of ancient predatory protists are rarely considered a major factor in the diversification of animals during the late Proterozoic/early Cambrian . This project will test hypothesis that predation on metazoans is widespread among basal forams, and if supported by analyses of the new protein-coding sequence data, then the role of these protists in Neoproterozoic ecosystems will need to be reevaluated. The objectives of the research are to: test the validity of the foram phylogenetic hypotheses currently based solely on single gene sequence data; examine the ultrastructure of representative members of allogromiid clades; explore the origin of polar forams using the new molecular phylogenetic and structural data; further examine the trophic strategies of allogromiids; and to determine if carnivory is a fundamental nutritional mode for basal forams, or a special derived character. Additional broader impacts of this research include training of underrepresented groups through both grass-roots efforts and formal participation in national federally funded education programs.