Foraminiferal genotype adaptation and their potential to enhance palaeoceanographic proxies

有孔虫基因型适应及其增强古海洋学代理的潜力

• 批准号: NE/D009707/1
• 负责人: Kathryn Frances Darling
• 金额: $ 38.42万
• 依托单位: University of Edinburgh
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FD009707%2F1
• 关键词: Foraminiferal; genotype; adaptation; their; potential

Planktonic foraminifers (forams) are an important group of single-celled organisms that live in the marine plankton. Their hard shells of calcium carbonate, imprinted with a chemical record of the environment in which they grew, are preserved as microfossils in the sediments where they have accumulated over millions of years. Researchers use them to reconstruct ocean circulation and climate in the past by assuming that all shells of a morphospecies (species defined by shape) were constructed within the same environmental range. Using a unique DNA marker in living forams, I have been able to show that this is not true. Each morphospecies often has several distinct genetic types (genotypes) and many are adapted to different environments. Genotypes therefore build their shells in different environments from one another and scientists are unknowingly using a mixture of different types. This is an unforeseen problem for researches using chemical evidence from fossil shells to understand past climate changes in these regions . During my Advanced Fellowship, my principle task has been to assess genetic variation within important morphospecies and the different adaptations of newly identified genotypes. I have collected thousands of samples to date from the high Arctic to the Antarctic, targeting regions of special interest to scientists who investigate changes in the past climate. Forams can be carried over great distances in the ocean currents and although there seem to be few barriers to dispersal, individual genotypes do have different adaptations and do not live everywhere. Some are more adapted to the heat or cold, others to different amounts or types of food. I have discovered that the same morphospecies living in both polar regions became genetically split around two million years ago when the cold glacial period began. The Antarctic ones also diverged again later and one become adapted to live in the extreme environment of the sea-ice while others have found themselves left behind, isolated in a cold current following the last glacial period. All this knowledge tells us about how life splits up into different species in the ocean and I have alerted scientists to many of these new evolutionary discoveries in leading journals. For past climate reconstruction, pooling several genotypes together must impose error into researcher's calculations and climate models. My evidence on the genetic diversity and ecology of living forams in the cold regions of the high latitude oceans has highlighted and solved some of these problems. I have provided scientists with new ways of improving accuracy in fossil record interpretation by utilising the changing shapes of foram shells in these regions. It is now a high priority to investigate the wind driven upwelling regions of the tropical and subtropical waters which play an equally vital role in earth's climate system to determine the genotypic structure of these quite different ecosystems. I propose to sample these regions during three separate cruises in the Indian and Pacific Oceans to determine which genotypes live there and the specific water column conditions they live in. I will combine genotyping at different depths with high resolution chemical analyses of the different layers of their shell produced during their life cycle. An extensive investigation into genotype shell shape will be carried out to facilitate their identification in the fossil record. Improving the resolution of present day low latitude data on the relationship between shell geochemistry and the physical environment in which genotypes grow is vital for past climate modelling. This work will be done in collaboration with a strong team of experts who work on the reconstruction of past climate both in the UK and abroad. In addition, a new data base of all genotyped specimens and their location is being compiled which will be made available for use by the scientific community when complete.

浮游有孔虫是生活在海洋浮游生物中的一类重要的单细胞生物。它们坚硬的碳酸钙外壳上印着它们生长环境的化学记录，作为微化石保存在沉积物中，它们在沉积物中积累了数百万年。研究人员利用它们来重建过去的海洋环流和气候，假设一个形态种（由形状定义的物种）的所有外壳都是在相同的环境范围内建造的。使用活有孔虫中的独特DNA标记，我已经能够证明这不是真的。每个形态种通常有几个不同的遗传类型（基因型），许多适应不同的环境。因此，基因型在不同的环境中构建它们的外壳，科学家们在不知不觉中使用了不同类型的混合物。这是一个不可预见的问题，研究人员使用化石贝壳的化学证据来了解这些地区过去的气候变化。在我的高级奖学金期间，我的主要任务是评估重要形态物种的遗传变异和新发现的基因型的不同适应。迄今为止，我已经收集了从高纬度北极到南极的数千个样本，目标是调查过去气候变化的科学家特别感兴趣的地区。有孔虫可以在洋流中携带很远的距离，虽然似乎没有什么障碍扩散，但个别基因型确实有不同的适应性，并不是到处都有。有些人更适应热或冷，其他人则适应不同数量或类型的食物。我发现，生活在两极地区的相同形态物种在大约200万年前寒冷的冰川期开始时发生了基因分裂。南极洲的人后来也再次分开，一个人适应了海冰的极端环境，而另一个人则发现自己落后了，在最后一个冰川期之后的寒流中被孤立。所有这些知识都告诉我们生命是如何在海洋中分裂成不同物种的，我已经提醒科学家注意领先期刊上的许多新的进化发现。对于过去的气候重建，将几种基因型汇集在一起必然会给研究人员的计算和气候模型带来误差。我关于高纬度海洋寒冷地区活有孔虫的遗传多样性和生态学的证据突出并解决了其中一些问题。通过利用这些地区有孔虫外壳形状的变化，我为科学家们提供了提高化石记录解释准确性的新方法。研究热带和亚热带沃茨的风驱动的上升流区域，以确定这些完全不同的生态系统的基因型结构，现在是一个高度优先事项，这些水域在地球气候系统中起着同样重要的作用。我建议在印度洋和太平洋的三次独立巡航中对这些区域进行采样，以确定哪些基因型生活在那里以及它们生活的特定水柱条件。我将结合联合收割机在不同深度的基因分型和高分辨率的化学分析，对它们在生命周期中产生的不同层的外壳进行分析。将对基因型壳形进行广泛的调查，以便于在化石记录中识别它们。提高当今低纬度数据的分辨率，了解壳层地球化学与基因型生长的物理环境之间的关系，对于过去的气候模拟至关重要。这项工作将与一个强大的专家团队合作完成，他们致力于重建英国和国外的过去气候。此外，正在编制一个新的数据库，其中包括所有基因型样本及其位置，完成后将提供给科学界使用。

项目成果

Ecological partitioning and diversity in tropical planktonic foraminifera.

• DOI: 10.1186/1471-2148-12-54
• 发表时间: 2012-04-16
• 期刊: BMC evolutionary biology
• 影响因子: 3.4
• 作者: Seears HA;Darling KF;Wade CM
• 通讯作者: Wade CM

Methodology for Single-Cell Genetic Analysis of Planktonic Foraminifera for Studies of Protist Diversity and Evolution

• DOI: 10.3389/fmars.2016.00255
• 发表时间: 2016-12
• 期刊: Frontiers in Marine Science
• 影响因子: 3.7
• 作者: Agnes K. M. Weiner;R. Morard;M. Weinkauf;K. Darling;Aurore André;F. Quillévéré;Y. Ujiié;C. Douady;C. de Vargas;M. Kučera

PFR2: a curated database of planktonic foraminifera 18S ribosomal DNA as a resource for studies of plankton ecology, biogeography and evolution

• DOI: 10.1111/1755-0998.12410
• 发表时间: 2015-11-01
• 期刊: MOLECULAR ECOLOGY RESOURCES
• 影响因子: 7.7
• 作者: Morard, Raphael;Darling, Kate F.;de Vargas, Colomban
• 通讯作者: de Vargas, Colomban