Inferring dispersal patterns in aquatic insects from Bayesian gene flow analysis and model selection

虽然扩散是了解生物分布的核心生活史特征，但对淡水生物中的扩散速度和方式知之甚少。对于远距离扩散(&gt；10公里)尤其如此，这对新的或重新储存的栖息地的(重新)殖民很重要。与全息无脊椎动物不同，大多数水生昆虫不仅限于在河流中扩散，而且在有翅膀的成虫阶段有可能活跃地在陆地上扩散。我们选择了三种不同目的水生昆虫(头翅目、翼翅目、毛翅目)作为模式物种，检验了分生昆虫种群通过成虫远距离(10公里)的扩散通过基因流动而有效地跨越河流流域的假设。目前正在进行的基因流动的速度和方向将在Fulda/Wera溪流系统和邻近集水区的溪流内部和溪流之间进行调查。首先，我们将使用高分辨率微卫星分析来研究流域内和流域间种群的遗传分化。为了区分现在和过去的基因流动，我们将使用基因分型数据来检查最近的移民，并将他们分配到来源种群。这种方法将使我们能够估计我们研究区域内所有三个模式物种目前正在进行的基因流动。此外，我们将在不同的扩散速度和方式的不同模型中实施历史丰度数据和遗传信息。每个物种的最佳模型将通过模型选择来选择。收集关于三个模式物种的扩散模式(溪流与跨溪流)和扩散速率的信息将有助于了解热带系统中水生昆虫种群的连通性，并将有助于我们理解恢复的淡水生态系统中的再定殖化过程。

Although dispersal is a central life-history trait for the understanding of organismal distributions, little is known regarding dispersal rates and modes in freshwater organisms. This is especially true for long-distance dispersal (>10km) which is important for (re-)colonization of new or re-stored habitats. In contrast to hololimnic invertebrates, most aquatic insects are not solely restricted to instream dispersal, but are potentially capable of active over-land dispersal in the wing-carrying adult stage. We chose three species of aquatic insects from different orders (Ephemeroptera, Plecoptera, Trichoptera) as model species to test the hypothesis that populations of merolimnic insects are effectively connected across stream catchments by gene-flow through adult long-distance (>10km) dispersal. Rates and directions of currently ongoing gene flow will be investigated within and among streams in the well-characterized Fulda/Werra stream system and adjacent catchments. First we will investigate genetic differentiation of populations within and among catchments using high-resolution microsatellite analysis. In order to distinguish between present and past gene flow, we will use genotypic data to check for recent immigrants and to assign them to source populations. This approach will allow estimating currently ongoing gene flow for all three model species within our study region. In addition, we will implement historical abundance data and genetic information in various models differing in the rates and modes of dispersal. Best models for each species will be chosen using model-selection. Gathered information on dispersal modes (in-stream vs. across-stream) and rates of the three model species will help to understand connectivity of aquatic insect populations in lotic systems and will contribute to our understanding of recolonization processes in restored fresh-water ecosystems.