The influence of Holocene sea-ice variability on Arctic biota: using the past to predict the future

海冰为许多北极物种提供了重要的季节性或多年性栖息地和扩散走廊，并对其他物种起着主要的地理屏障作用；因此，它影响着海洋和陆地生物群的分布、基因流动和物种相互作用。据预测，由于气候变化，本世纪北冰洋将出现季节性无冰现象。这种变化的生态和进化后果仍然知之甚少，尽管高度依赖海冰来完成其生活史的物种可能特别脆弱。我们对物种如何对海冰的长期时空变化作出反应的理解有限，这阻碍了我们量化海冰损失影响的能力。这是由于缺乏许多物种的历史和现代观测数据，以及末次盛冰期以来海冰自然变率的数据稀少，尽管高分辨率海冰重建正在出现。另一个挑战是改善海冰作为物种动态的主要驱动因素的归属，因为由于缺乏适当的海冰和/或生物数据，在许多情况下甚至根本没有使用海冰数据，许多关联仍然是推测性的。该项目旨在通过提高我们对海冰与北极物种之间长期相互作用的理解，特别是：海冰变化如何影响全新世（11700年至今）的北极生物群，来推进对当前海冰损失影响的预测。研究的三个主要领域是：1。在全新世期间，与冰有关的特定物种的时空历史如何？全新世海冰与北极物种动态的关系是什么？海冰如何继续影响植物在北极的传播，现代植物传播途径与重建的传播途径相比如何？对哪些物种最依赖海冰，哪些物种因此最有可能面临海冰消失的风险进行预分析系统回顾，将有助于为重点物种的选择提供信息，并有助于产生假设。该项目将使用新兴的基于全新世北极海冰的高分辨率浮木重建（Hole & Macias-Fauria, 2017），这将提供海冰动态自然变化的详细信息。对于问题(i)，将编译来自化石的古代DNA和现代分子数据，通过种群遗传分析（人口变化、种群连通性和遗传多样性）和物种分布建模（范围转移和分散事件）来重建和模拟物种动态。对于（iii），该项目将结合海冰和物种动态的重建，从协变的时空格局中评估因果关系。该分析还将解释物种动态变化的其他可能来源，例如：气候、地理和生物相互作用的其他方面。此外，由于北极的可及性越来越高，物种动态也可能受到北极人为压力增加的影响。问题（iv）将需要进行实地考察，分析沿海海冰沉积在斯瓦尔巴群岛海滩上的植物材料。这将包括繁殖体的收集、鉴定和可行性测试，可能的来源区域鉴定，以及分析现代传播途径是否与研究植物的时空历史相一致。有可能与斯瓦尔巴群岛总督的环境部合作开发一个公民科学项目。该项目的结果将揭示海冰在历史上对北极生物群的影响程度，并对当前海冰损失的潜在生态和进化反应提供见解；从而能够更准确地预测北极气候变化的影响。

Sea ice provides an important seasonal or perennial habitat and dispersal corridor for many Arctic species and acts as a major geographic barrier for others; it therefore influences the distributions, gene flow, and species interactions of marine and terrestrial biota. The Arctic Ocean is predicted to become seasonally ice-free this century as a result of climate change. The ecological and evolutionary consequences of this change remain poorly understood, although species with a high reliance on sea ice to complete their life histories are likely to be particularly vulnerable. Our ability to quantify the impacts of sea ice loss is hampered by our limited understanding of how species respond to long-term spatial and temporal variation in sea ice. This is due to a shortage of historic and modern observational data for many species, as well as sparse data on the natural variability of sea ice since the Last Glacial Maximum, although high-resolution sea ice reconstructions are emerging. Another challenge is to improve attribution of sea ice as the primary driver of species dynamics, as many associations remain speculative due to lack of appropriate sea ice and/or biotic data, in many cases not even using sea ice data at all.This project aims to advance predictions of impacts of current sea ice loss by improving our understanding of the long-term interactions between sea ice and Arctic species, specifically: how sea ice variability influenced Arctic biota during the Holocene (11,700 years - present). The three main areas of study are:i. What is the spatiotemporal history of selected ice-associated species during the Holocene?ii. What is the relationship between sea ice and Arctic species dynamics in the Holocene?iii. How does sea ice continue to influence plant dispersal in the Arctic, and how do modern plant dispersal pathways compare with reconstructed dispersal pathways?A pre-analysis systematic review of which species are most dependent on sea ice, and which are therefore most likely to be at risk from sea ice loss, will help inform selection of focal species and help generate hypotheses. The project will use emerging high-resolution driftwood-based reconstructions of Holocene Arctic sea ice (Hole & Macias-Fauria, 2017) which will give detailed information on the natural variability of sea ice dynamics. For question (i), ancient DNA from fossils and modern molecular data will be compiled to reconstruct and model species dynamics using: population genetic analysis (demographic change, population connectivity, and genetic diversity) and species distribution modelling (range shifts and dispersal events). For (iii) the project will combine reconstructions of sea ice and species dynamics to assess causality from the spatiotemporal patterns of covariability. The analysis will also account for other possible sources of variation in species dynamics, for example: other aspects of climate, geography, and biotic interactions. In addition, species dynamics may also be impacted by increasing human-driven pressures in the Arctic, as a result of its increasing accessibility. Question (iv) will entail fieldwork analysing plant material that is deposited by coastal sea ice on Svalbard beaches. This will involve collection, identification, and viability-testing of propagules, identification of possible source regions, and an analysis of whether modern dispersal pathways agree with the spatiotemporal histories of the study plants. There is potential to develop a citizen-science project in collaboration with the Environment Department of the Svalbard Governor.The results from this project will reveal the extent to which sea-ice has historically influenced Arctic biota, and give insights into potential ecological and evolutionary responses to current sea ice loss; thereby enabling more accurate predictions of the impacts of climate change in the Arctic.