Biological invasions in lakes - genetic diversity, timing and local adaptation

由于全球流动和全球变化，许多动植物物种在世界范围内分散并在新的地区建立。这些生物入侵对当地和区域群落产生负面影响，并可能破坏当地的多样性。此外，生态系统的变化可能会极大地影响其功能。特别是在水生系统中，许多入侵物种造成了严重的生态和经济后果，如斑马贻贝、虹鳟鱼、水蚤水蚤和具有潜在毒性的蓝藻（蓝绿藻）。确定了决定物种入侵成功的三个主要因素：(i)入侵物种的生态特征，（ii）常驻物种的生态特征和（iii）栖息地特征。高等植物和动物的入侵已经得到了广泛的研究，但对微生物的入侵却知之甚少。本研究项目将利用一种生态和经济相关的模式生物raciborskii来研究这些问题。中心问题解决了入侵物种遗传多样性的作用（参见第1章）和主要常驻竞争对手的遗传多样性（参见第2章）。根据理论考虑，在入侵事件中，随着进入新系统的基因型数量的增加，入侵成功率也会增加。另一方面，假设主要常驻竞争者的高遗传多样性阻碍了入侵的成功。在一系列的实验室入侵实验中，将使用10种不同的基因型对寄生浮游植物群落（有和没有其主要竞争对手）的入侵成功进行研究。此外，通过实验模拟季节性浮游生物的发展，将调查在入侵期间是否存在促进或阻碍机会之窗。此外，还将测试潜在的消费者（萼花臂尾轮虫，Rotatoria）是否已经适应了几十年前raciborski入侵的湖泊的新资源。该项目将有助于填补入侵生物学在微生物入侵、遗传多样性和局部适应等领域的知识空白。

Due to global mobility and global change many animal and plant species are worldwide dispersed and establish in new regions. These biological invasions negatively affect local and regional communities and may disturb the local diversity. Furthermore, changes in the ecosystems may drastically impact their functions. In aquatic systems, in particular, many invasive species have caused serious ecological and economic consequences such as the zebra mussel, the rainbow trout, the water flea Daphnia lumholtzi and the potentially toxic cyanobacterium (blue-green alga) Cylindrospermopsis raciborskii. Three main factors have been identified determining the invasion success of species: (i) the ecological characteristics of the invading species, (ii) the ecological characteristics of the resident species and (iii) the habitat characteristics. Invasions of higher plants and animals have been often investigated, whereas there is a gap of knowledge in microbial invasions. These will be investigated in this research project by using an ecologically and economically relevant model organism C. raciborskii. The central question addresses the role of the genetic diversity of the invasive species (cf. i) and the genetic diversity of the main resident competitor (cf. ii). According to theoretical considerations, the invasion success increases with an increasing number of genotypes entering a new system at an invasion event. On the other hand it is hypothesized that a high genetic diversity of the main resident competitor hampers an invasion success. In a series of laboratory invasion experiments the invasion success of C. raciborskii into resident phytoplankton communities (with and without its main competitor) will be performed using 10 different genotypes. Furthermore, with an experimentally simulated seasonal plankton development it will be investigated whether a window of opportunity exists during that an invasion is either facilitated or hampered. Additionally, it will be tested whether potential consumers (Brachionus calyciflorus, Rotatoria) have been locally adapted to the new resource in lakes where C. raciborskii has been invaded some decades ago. This project will contribute to fill the gap of knowledge in invasion biology in the field of microbial invasions, genetic diversity and local adaptation.