Genetic and ecological drivers of successful bioinvasion by Gracilaria vermiculophylla

自20世纪80年代以来，亚洲特有的红藻江豚入侵大西洋和东太平洋海岸，对群落结构和生态系统功能造成了严重影响。虽然生态生理和化学研究表明，一些生态性状和对捕食者的化学防御对其在全球范围内的快速入侵做出了相当大的贡献，但尚未有研究揭示遗传和/或表观遗传变异以及对新环境条件的驯化/适应速度是否是大规模入侵成功的原因。我们建议阐明蠕虫入侵背后的生态遗传机制。中方的目标将包括：(1)通过转录组学确定原生和入侵种群中具有不同表达谱的基因，并分析这些基因如何有助于对各种新环境的生态适应；(2)利用AFLP基因分型技术评估本地和入侵种群内及其之间的遗传多样性；(3)利用MS-AFLP检测主导大西洋和东太平洋海岸入侵的特定线粒体单倍型蠕虫(G.)(H6)内的表观遗传变异；以及(4)在种群水平上检测遗传变异，表明在入侵期间，强大的基因类型在应激条件下选择性地存活。在德国方面，目标是(1)确定本地种群和入侵种群是否对环境胁迫表现出不同的耐受宽度，(2)评估本地种群和入侵种群之间的胁迫敏感性(适应基础)的种内变异量，(3)比较本地种群和入侵种群对新环境条件的驯化/适应速率(即速度)，以及(4)调查相关微生物在调节宿主对胁迫反应中的作用。该联合项目不仅将提供对成功入侵海藻背后的遗传和生态机制的全面了解，还将有助于开发对候选入侵海藻的更有效的监测管理，这将缓解和防止全球范围内的海藻入侵。

The Asia-endemic red alga Gracilaria vermiculophylla invaded the Atlantic and Eastern Pacific coasts since the 1980s and has imposed drastic impacts on community structure and ecosystem function. Although eco-physiological and chemical studies revealed that some ecological traits and chemical defense to predators made considerable contribution to its rapid global invasion, no studies were conducted to reveal whether genetic and/or epigenetic variations and the rate of acclimation/adaptation to new environmental conditions account for the large-scale invasion success of G. vermiculophylla. We propose to elucidate the eco-genetic mechanisms behind the invasion of G. vermiculophylla. The aims of the Chinese side will include (1) the identification of genes with distinct expression profiles in native and invasive populations by transcriptomics and the analysis of how these genes contribute to the ecological adaptation to a wide range of novel environments, (2) the assessment of genetic diversity in and between native and invasive populations using AFLP genotyping, (3) the detection of epigenetic variation within the specific mitochondrial haplotype G. vermiculophylla (H6), which dominated the invasion of Atlantic and E Pacific coasts using MS-AFLP, and (4) the detection of genetic shifts at the population level that indicate selective survival of robust genotypes under stressful conditions during invasion. On the German side the aims will be (1) to determine whether native and invasive populations exhibit different tolerance widths towards environmental stress, (2) to assess the amount of intraspecific variance of stress sensitivity (the basis for adaptation) between native and invasive populations, (3) to compare the rate (i.e. speed) of acclimation/adaptation of native and invasive populations to new environmental conditions and (4) to investigate the role of associated microorganisms in the modulation of host responses to stress. The joint project will not only provide a comprehensive understanding of genetic and ecological mechanisms underlying successful seaweed invasion, but also help to develop a more effective monitoring management for candidate invasive seaweeds, which will mitigate and prevent seaweed invasions worldwide.