Combined genetic, morphological and ecological approaches to reduce uncertainty in palaeoclimate reconstructions using benthic foraminifers

结合遗传、形态学和生态学方法减少利用底栖有孔虫重建古气候的不确定性

基本信息

批准号：
NE/G020310/1
负责人：
Kathryn Frances Darling
金额：
$ 40.98万
依托单位：
University of Edinburgh
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2010
资助国家：
英国
起止时间：
2010 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FG020310%2F1
关键词：
Combined genetic morphological ecological approaches

项目摘要

It is very important for us to find out how climate changed in the past. Without knowing, we cannot predict how the future climate might behave. Global, systematic measurements of climatic variables have only been collected over the last few decades but we need to know how it varied through longer periods of time. We particularly need to know about this in the North Atlantic shelf seas which are currently experiencing accelerating climate change. The layers of ocean sediments in these regions contain the skeletons of microscopic organisms which can provide information about past climate. Benthic foraminifers in particular live in these shallow ocean habitats and their microscopic calcite shells accumulate through time providing a high resolution record of past environments. Communities of specific species (assemblages) are associated with the regional habitats of the shelf seas and this relationship is applied to similar assemblages found in time slices in the sediments (transfer functions). Forams also incorporate into their shells the physical and chemical signatures of the seawater in which they grow. This can be used as a geochemical 'proxy' to reconstruct the past environment in which they lived. All these past climate reconstructions are based on the assumption that the shells of a single species were constructed in the same range of environmental conditions. Using a unique DNA marker in living forams, we know that this is not always true. Individual morphospecies sometimes represent several distinct genetic types (genotypes) which may be adapted to different environments within a morphospecies range. It is highly likely that these are different species. Scientists are unknowingly analysing a mixture of different species because they look very similar (cryptic species). This will introduce noise and possible error into the data of both transfer function methods and geochemical proxies. To overcome this, we propose to genotype all the important benthic morphospecies used for past climate reconstruction throughout the regional habitats (biogeographic provinces) of the mid to high latitudes of the northeast Atlantic. We will sample these with the help of our four project partners from Norway and Iceland. We also have to bear in mind that these regions experience a wide range of environmental conditions as the seasons change. To address this, we will take samples from regions where seasonal studies are being carried to find out whether different genotypes appear as the environmental conditions change. Central to this study will be an extensive morphological investigation of shell shape to find out whether we can find subtle differences to help recognise the new genotypes in the modern ocean and most importantly, in the fossil record. We hope to genetically and morphologically define all important benthic morphospecies used for past climate reconstruction in the North East Atlantic to produce a unified classification scheme. From our high resolution sampling, we will be able to produce a new bioprovince distribution map for the present day northeast Atlantic/Arctic. We will discover whether 'generalist' species really occupy different bioprovinces or represent a series of different cryptic species with different ecologies. Finding identifiable new species will improve our understanding of how bioprovinces have migrated North/South as the glacial cycles have come and gone. Do different cryptic species appear in the same place as the seasons change? Their recognition would allow the exploration of seasonality in the fossil record. Do foram shells of the same species have a different shape in different environments? Confirmation will provide evidence of specific environmental conditions in the present day and in the past. This link between present and past also provides important clues about how extreme changes in these dynamic marine environments affect the survival of species and drive their evolution through time.

对于我们来说，找出过去气候如何变化非常重要。在不知道的情况下，我们无法预测未来的气候如何行事。在过去的几十年中，仅收集了气候变量的全球系统测量，但我们需要知道它在更长的时间内如何变化。我们特别需要在北大西洋货架海洋中了解这一点，这些货架海洋目前正在加速气候变化。这些区域中的海洋沉积物层包含微观生物的骨骼，这些骨骼可以提供有关过去气候的信息。底栖有孔虫尤其生活在这些浅海栖息地及其微观方解石贝壳中积聚的时间，从而提供了过去环境的高分辨率记录。特定物种（组合）的群落与货架海的区域栖息地有关，这种关系应用于沉积物中的时间切片中的类似组合（转移功能）。孔子还将其生长的海水的物理和化学特征纳入其壳中。这可以用作地球化学的“代理”来重建它们所生活的过去环境。所有这些过去的气候重建都是基于以下假设：单个物种的壳是在相同的环境条件下构建的。在活孔中使用独特的DNA标记，我们知道这并不总是正确的。单个形态种以有时代表几种不同的遗传类型（基因型），这些遗传类型可能适用于形成范围内的不同环境。这些是不同的物种。科学家在不知不觉中分析了不同物种的混合物，因为它们看起来非常相似（隐性物种）。这将引入噪声和可能的误差，并将转移函数方法和地球化学代理的数据引入数据中。为了克服这一点，我们建议在东北大西洋中部至高纬度地区的整个区域栖息地（生物地理省）中用于过去气候重建的所有重要底栖形态。我们将在来自挪威和冰岛的四个项目合作伙伴的帮助下对这些进行采样。我们还必须记住，随着季节的变化，这些地区经历了广泛的环境条件。为了解决这个问题，我们将从进行季节性研究的区域中采集样本，以找出随着环境条件的变化，是否出现了不同的基因型。这项研究的核心将是对壳形状的广泛形态研究，以找出我们是否可以找到微妙的差异来帮助识别现代海洋中的新基因型，最重要的是，在化石记录中。我们希望在遗传和形态上定义所有重要的底栖形态，用于在东北大西洋的过去气候重建中，以产生统一的分类方案。从我们的高分辨率抽样中，我们将能够为当今东北大西洋/北极的新生物植物发行图生成新的生物媒介分销图。我们将发现“通才”物种是否真正占据了不同的生物环境或代表具有不同生态的一系列不同的隐性物种。找到可识别的新物种将提高我们对生物益处如何迁移到冰川周期来来往往的情况下迁移的理解。不同的神秘物种与季节变化相同的位置是否出现？他们的认可将允许化石记录中探索季节性。在不同环境中，同一物种的孔壳有不同的形状吗？确认将提供当今和过去的特定环境条件的证据。现在和过去之间的这种联系还提供了有关这些动态海洋环境中极端变化如何影响物种生存并推动其随着时间推移进化的重要线索。