Genetic and ecological characterization of the invasive freshwater jellyfish Craspedacusta sowerbii

人口流动性和连通性增加的一个后果是越来越多地将非本地物种引入生态系统。在非本地淡水水母Craspedacusta sowerbii的情况下，该物种的引入在淡水浮游生物群落中创造了一个新的功能性行业，因为水母在欧洲湖泊群落中没有代表数百万年。淡水水母Craspedacusta sowerbii（Lankester 1880）起源于亚洲（中国），已知在德国湖泊中存在约100年。今天，至少有100个不同地点的记录是已知的，根据现有的知识，种群中的水母是单性的，并且被认为是基因相同的，这表明只有一个或几个成功的克隆。Craspedacusta sowerbii有一个宏成和部分生殖的生活史，包括一个小的（1-2毫米）无性繁殖的底栖水螅。C. sowerbii的分布可能已经比水母（1-2厘米大小）的分布更广。小息肉可能经常被忽视，自由游动的水母阶段的大量发生的记录占主导地位。在一定的水温以上，水螅可以释放水母到远洋。因此，预测的水温上升可能导致水母分布的快速增加。因此，观察到的个体数量高达1000 ind/m-2的水母对水生食物网动态的影响是可以预期的，但尚未详细说明。在实验室实验中，将确定食肉水母的食物选择性、同化和摄食效率，提供与其他食肉生物竞争的基本信息。沿着水母丰度梯度进行的野外围隔实验将调查水母的营养位置、对浮游植物的级联效应以及水母介导的能量和物质的中上层-底栖通量。此外，实地调查将调查和比较有无水母的湖泊中的中上层食物网动态。实地调查将允许分析性别，基因型和环境之间的关联，并将有助于回答有关水母的长期建立和进化动力学的问题。遗传多样性和群体结构。sowerbii将使用高分辨率微卫星和ITS和COI标记进行研究。遗传分析将显示，如果不同的基因型存在于息肉，因此在水母阶段，如果只有一个克隆是占主导地位的，或者如果多个引进可能。该物种的遗传多样性和生态功能的综合分析，将允许更好地了解因果关系的水生食物网内暴露于入侵的非本地物种。

A consequence of the increasing mobility and connectivity of human populations is the rising introduction of non-native species into ecosystems. In case of the non-native freshwater jellyfish Craspedacusta sowerbii the introduction of this species created a new functional guild within freshwater plankton communities, as jellyfish were not represented in European lake communities for millions of years. The freshwater jellyfish Craspedacusta sowerbii (Lankester 1880) is originating from Asia (China) and known to be present in German lakes since about 100 years. Today records from at least 100 different locations are known and according to available knowledge jellyfish within populations are unisexual and assumed to be genetically identical suggesting the spread of only one or few successful clones. Craspedacusta sowerbii has a metagenetic and meroplanktonic life cycle, including a small (1-2 mm) benthic polyp reproducing asexually. C. sowerbii may be already far more distributed as suggested by observation of medusae (1-2 cm in size). The small polyp may often be unnoticed and records of mass occurrences of the free-swimming medusoid stage predominate. Above a certain water temperature polyps can release medusae into the pelagial. Predicted increasing water temperatures can therefore result in a fast increase of the distribution of medusae. Hence, with observed individual numbers up to 1000 ind/m-2 effects of medusae on aquatic food web dynamics are expectable but not specified in detail yet. In laboratory experiments food selectivity, assimilation and ingestion efficiencies of the carnivore jellyfish will be determined, giving basic information on competitiveness with other planktivorous organism. Field mesocosm experiments along jellyfish abundance gradients will investigate trophic positions of jellyfish, cascading effects down to phytoplankton and pelagic-benthic fluxes of energy and matter mediated by jellyfish. Additionally, field surveys will investigate and compare pelagic food web dynamics in lakes containing jellyfish or not. The field surveys will allow to analyse the association between sex, genotype and environment and will help to answer questions regarding long-time establishment and evolutionary dynamics of jellyfish. Genetic diversity and population structure of C. sowerbii will be studied using high-resolving microsatellites and ITS and COI markers. Genetic analyses will show if different genotypes are present in the polyp and consequently in the medusoid stage, if only one clone is dominant or if multiple introductions are likely. The combined analyses of the genetic diversity and the ecological function of this species will allow a better understanding of cause and effect relationships within aquatic food webs exposed to invasion by non-native species.