What makes some species highly invasive? An experimental study in the major crop pest Arionid slugs

入侵物种严重影响生态系统服务和粮食安全。软体动物现在被认为是对食品安全的主要威胁，因为禁止使用杀螺剂，以及它们对控制措施的适应能力和高内在增长率。这些重要植物病原体的杂食性媒介与当地特有物种杂交并将其赶走。侵入性鼻涕虫的到来与当地生物多样性的下降有关，对粮食安全和生态系统稳定具有深远影响。入侵性状在多大程度上是物种特有的，这是杂交/导入或携带/引入本地范围的微生物区系的结果，目前尚不清楚。为了对入侵的根本原因(S)有新的见解，我们将使用害虫Arion uggaris和A.Flagellus1作为一个实验系统来量化与本地物种相互作用的表型、基因型和微生物后果。很少有分类学家专门研究这组近缘种，它们频繁的杂交和兼性的自育繁殖系统混淆了鉴定。分类学上的混乱和缺乏高分辨率的分子工具意味着入侵形式与地方病和随后的入侵浪潮的定殖史、分布和遗传相互作用仍然知之甚少。与兄弟分类群的杂交被认为有利于入侵(I)通过获取和利用植物病原菌作为肠道共生体，帮助植物材料的消化，和/或(Ii)通过反复导入线粒体基因，作为适应其新环境的来源2。因此，有必要评估入侵杂交种和地方性杂交种的区别潜力，以从携带和混合微生物区系中获得选择优势，以及它们作为植物病原菌载体的能力，从而使入侵杂交种可能构成新的生态和农业威胁。线粒体通过核基因组相互作用在促进和促进入侵物种适应环境方面的重要性也仍然难以捉摸。你将把特定于分类单元的解剖、形态和颜色特征与尖端标记(SNPs)相结合，利用来自原生范围中心的个体，通过‘基因测序’方法和线粒体测序，对每个大型的杂色类分类单元进行第一次客观定义。这将为评估入侵、量化特有基因组的同化以及它们对入侵的贡献提供标记。你将量化有助于入侵潜力的特征(例如繁殖力、寿命、发育期间的存活率、温度、病原体耐受性和微生物组多样性的标记)。你将使用从第一次接触起35年的样本中的当代和历史材料，评估杂种优势(极端遗传变异性)、微生物区系和有丝分裂-核相互作用对入侵的贡献。你将使用包括高分辨率呼吸测量在内的一系列最先进的生理学工具，研究从线粒体水平到整个生物体的有丝分裂-核相互作用的后果。最后，您将通过qPCR3确定植物病原体与分类群的关联和入侵水平，并通过使用回交群体评估选定病原体对入侵性状的贡献来调查植物病原体的传播。所有发现都将被纳入基于生态学理论的模型中，以比较不同气候情景下入侵形式的实际传播和预测传播，并对鼻涕虫-植物-病原体的相互作用和流行病学进行建模。

Invasive species significantly impact ecosystem services and food security. Molluscs are now considered a major threat to food security, with banning of molluscicides, and their resilience to control measures and high intrinsic rates of increase. These omnivorous vectors of important plant pathogens hybridise with and drive out endemic species. Arrival of invasive slugs associates with declines in local biodiversity, with profound implications for food security and ecosystem stability. The extent to which invasive traits are species-specific, a consequence of hybridization/introgression or carriage/introduction of native-range microbiota remains unknown.To gain new insights on the underlying cause(s) of invasions UK invasive arionid slugs, the pests Arion vulgaris and A. flagellus1 will be used as an experimental system to quantify phenotypic, genotypic and microbial consequences of interactions with native species. Few taxonomists specialize in this group of sibling species, whose frequent hybridization1 and facultative self-fertile breeding system confound identification. Taxonomic confusion and lack of high resolution molecular tools means colonization history, distributions and genetic interaction of invasive forms with endemics and succeeding invasion waves remain poorly known1. Hybridization with sibling taxa has been proposed to favour invasiveness (i) through the acquisition and exploitation of plant pathogenic bacteria as gut commensals, aiding digestion of plant material, and/or (ii) through the recurrent introgression of mitochondrial genes that could serve as source of adaptations to their new environment2. Hence, there is a need to assess the differential potential of invasive and endemic arionids to gain selective advantage from carriage and admixture of microbiota, and their ability to act as vectors of plant pathogenic bacteria, such that invasive hybrids may pose novel ecological and agricultural threats. The importance of mitochondrial by nuclear genome interactions in facilitating and promoting adaption to the environment in invasive species also remains elusive. You will integrate taxon-specific anatomical, morphometric and colormetric traits with cutting edge markers (SNPs) from 'genotyping-by-sequencing' approaches and mitochondrial sequencing to make the first objective definition of each large arionid taxon, using individuals from native-range centres. This will provide markers to assess introgression, quantifying assimilation of endemic genomes and hence their contribution to invasion. You will quantify traits contributing to invasive potential (e.g. fecundity, longevity, survival during development, temperature, pathogen tolerance and markers of microbiome diversity). You will assess the contributions of heterosis (extreme genetic variability), microbiota, and mito-nuclear interactions to invasions, using contemporary and historic material from samples spanning 35 years from first contact. You will study consequences of mito-nuclear interaction from the level of the mitochondria to whole organism using a wide range of state-of-the-art physiological tools including high resolution respirometry. Finally, you will determine association of plant pathogens with taxa and level of introgression by qPCR3 and investigate plant pathogen spread by assessing the contribution of selected pathogens to invasive traits using a backcross population. All findings will be incorporated into ecological theory-based models to compare actual and predicted spread of invasive forms under different climate scenarios and to model slug-plant-pathogen interactions and epidemiology.