Dispersal, the movement of individuals from their natal population to their breeding population, has important ecological and evolutionary consequences. In lotic freshwater systems, landscape features such as barriers or connectors, can affect dispersal and thus gene flow. It is of special interest to characterize population genetic structure in the presence of impassable barriers because they can restrict dispersal and thus isolate populations. On the other hand, connectors such as man-made canals connect watersheds that would otherwise be isolated, thereby enhancing gene flow and potentially genetically homogenizing populations. Freshwater mussels (Order: Unionida), many of which are highly threatened, have a unique life history involving parasitism on host fish species for larval development and dispersal. Landscape features that affect fish passage will consequently affect mussel dispersal and the maintenance of populations and metapopulations. This manuscript explores how landscape features affect the population genetic structure and genetic diversity of the freshwater mussel species Lampsilis siliquoidea, Fatmucket, in the southwestern Lake Ontario drainage. Data from seven microsatellite loci revealed that 1) waterfalls act as barriers for gene flow between freshwater mussel populations within the same river, 2) populations above the barrier had lower genetic diversity, 3) there was no detectable effect of man-made canals on genetic diversity and, 4) populations that were not hydrologically connected by a canal were marginally more differentiated than the populations connected by a canal. Landscape features can alter the connectivity within and between drainages thus changing the scale at which management will be effective.

分散，即个体从出生人口向繁殖人口的移动，具有重要的生态和进化后果。在流动淡水系统中，障碍物或连接器等景观特征会影响扩散，从而影响基因流动。在存在不可逾越的障碍的情况下表征种群遗传结构具有特别的意义，因为它们可以限制扩散并因此隔离种群。另一方面，诸如人造运河之类的连接器连接了原本会被隔离的分水岭，从而增强了基因流动和潜在的基因同质化种群。淡水贻贝（目：Unionida），其中许多受到高度威胁，具有独特的生活史，包括寄生在宿主鱼类上幼虫的发育和传播。影响鱼类通过的景观特征将因此影响贻贝的传播以及种群和集合种群的维持。这份手稿探讨了景观特征如何影响安大略湖西南部流域淡水贻贝物种Lampsilis siliquoidea, Fatmucket 的种群遗传结构和遗传多样性。来自七颗微型卫星的数据基因座揭示了 1) 瀑布作为同一河流内淡水贻贝种群之间基因流动的屏障，2) 屏障上方的种群遗传多样性较低，3) 人造运河对遗传多样性没有可检测到的影响，4 ) 未通过运河水文连接的种群比通过运河连接的种群差异略大。景观特征可以改变排水系统内部和排水系统之间的连通性，从而改变有效管理的规模。