Up to the north and down from the trees: Genetic signatures of expansion over a century of climate change and of a recent habitat shift in the Mangrove tree crab Aratus pisonii

气候变化是全球海洋和陆地生态系统物种分布范围变化的主要驱动力。据预测，范围的转移和扩大如果发生得太快，将侵蚀遗传多样性，降低物种对持续气候/环境变化的适应潜力。沿海物种在这方面研究不足，但特别脆弱，因为它们的生命周期经常在海洋和（半）陆地系统之间交替，两者都受到全球变化的影响。自然历史收藏品越来越被认为是独特的分子数据档案，以调查在进化的重要时间跨度上气候变化的这种后果。在这个项目中，红树林树蟹Aratus pisonii将作为研究系统。在世纪沿着佛罗里达东海岸向北沿着扩张后，有一份全面的收集记录，A.最近（自2012年以来），皮索尼在红树林分布范围以北的盐沼中开拓了迄今为止的外国栖息地。它为研究气候变化引起的分布范围扩大对（亚）热带甲壳类物种遗传多样性和种群结构的影响提供了一个极好的机会。该项目的主要目标是调查A.超保守元件（UCE）将用于目标富集高通量测序，以获得现代和历史标本的基因组数据，作为种群基因组分析的基础。基因组数据将进一步用于为物种分布建模提供信息，采用最近开发的集成建模方法。该项目将提供经验性的洞察力的变化，人口结构和遗传多样性的一个物种的范围扩展的历史记录良好。该研究系统作为一个案例研究，突出了遗传多样性对沿海物种在气候变化下的适应力的重要性。此外，将创建新的基因组资源，特别是第一个用于十足类甲壳动物的UCE探针集。该项目将分为两个阶段，分别在剑桥/马萨诸塞州哈佛大学比较动物学博物馆和不莱梅莱布尼茨热带海洋生物学中心举办。

Climate change is a major driver of changes in species’ distribution ranges in marine and terrestrial ecosystems worldwide. Range shifts and expansions are predicted to erode genetic diversity when occurring too quickly, reducing the adaptive potential of species towards ongoing climate/environmental change. Coastal species are understudied in this respect, but are especially vulnerable since their life cycles often alternate between marine and (semi-)terrestrial systems that are both affected by global change. Natural history collections are increasingly recognised as unique archives of molecular data to investigate such consequences of climate change over evolutionary significant time spans.In this project, the Mangrove tree crab Aratus pisonii will serve as study system. After expanding northwards along the Florida east coast during the 20th century, documented by a comprehensive collection record, A. pisonii recently (since 2012) colonised a hitherto foreign habitat, the salt marshes north of the distribution limit of mangroves. It provides an excellent opportunity to study the impacts of climate change-induced range expansions on genetic diversity and population structure in a (sub-)tropical crustacean species. The project’s main objective is an investigation of patterns of genetic diversity and population structure in A. pisonii at both, spatial and temporal scales, as a baseline for understanding the species’ habitat shift during its ongoing northward range expansion.Ultraconserved elements (UCE) will be used for target-enriched high-throughput sequencing to obtain genomic data from modern and historical specimens, as a basis for population genomic analyses. The genomic data will further be used to inform species distribution modelling, employing a recently developed ensemble modelling approach. The project will provide empirical insight into changes of population structure and genetic diversity in a species with a well-documented history of range expansion. The study system serves as a case study for highlighting the importance of genetic diversity for coastal species’ resilience under climate change. Additionally, new genomic resources, particularly the first UCE probe set for decapod crustaceans, will be created. The project will be divided in two phases, hosted at the Museum of Comparative Zoology at Harvard University, Cambridge/MA, and the Leibniz-Centre for Tropical Marine Biology, Bremen, respectively.