The genomic and adaptive consequences of extreme, human-mediated population decline

对野生生物种群数量严重下降的后果知之甚少。经历这种下降的物种的生存可能会受到以下因素的阻碍：适应不断变化的环境的能力有限、生育力下降和更容易患病-所有这些都源于遗传多样性低。当应用于由于人类活动而经历了人口瓶颈的系统时，基因组工具使我们能够检查近亲繁殖，遗传负荷，抗病性和适应性方面的基因组后果。我们的目的是了解极端的，快速的人口下降的后果，使用激烈的人为干预的例子，其中整个湖泊的鱼类种群被根除和repopulation.The引进的鲑鱼体外寄生虫Gyrodactylus salaris挪威导致野生大西洋鲑鱼种群的崩溃。因此，当局将鱼藤酮-一种广谱生物杀灭剂-应用于整个河流集水区，以杀死所有鱼类宿主。经过处理后，水道中就会重新放养来自当地鱼类种群的未受感染的人工繁殖幼鱼。2012年，Fusta流域（四个线性连接的亚北极湖泊）进行了鱼藤酮计划。在治疗前，鱼类群落包括湖间洄游褐鳟鱼。遗传评估显示显着的人口结构和高比例的溯河产卵鳟鱼在海上捕捞可以分配到Fusta人口。此外，这些分析检测基因座的选择表明当地适应整个系统。褐鳟鱼和溯河产卵的形式，特别是，经历了大幅下降，近年来，这种治疗可能会威胁到褐鳟鱼的遗传健康。该系统代表了一个独特的机会，以了解（一）极端瓶颈对物种基因组的影响，（二）遗传多样性的丧失如何影响免疫寄生虫和（三）快速适应的过程中发生的遗传depapartamate人口。

The consequences of severe population decline in wild organisms are poorly understood. Survival of species experiencing such declines may be hampered by a limited ability to adapt to changing environments, reduced fertility and greater susceptibility to disease - all stemming from low genetic diversity. When applied to systems that have experienced population bottlenecks as a result of human activities, genomic tools allow us to examine the genomic consequences in terms of inbreeding, genetic load, disease resistance and adaptability. Our aim is to understand the consequences of extreme, rapid population decline using an example of drastic human intervention in which the fish stocks of entire lakes were eradicated and repopulated.The introduction of the salmonid ectoparasite Gyrodactylus salaris to Norway resulted in the collapse of wild Atlantic salmon populations. Consequently, authorities applied Rotenone - a broad-spectrum biocide - to entire river catchments to kill all fish hosts. Once treated, waterways are restocked with uninfected captive-bred juveniles from local fish stocks. In 2012 the Fusta catchment (four linearly-connected sub-arctic lakes) underwent a rotenone program. Prior to treatment, fish communities included inter-lake migratory brown trout. Genetic assessment revealed significant population structure and a high proportion of anadromous trout caught at sea could be assigned to Fusta populations. Furthermore, these analyses detected loci under selection suggesting local adaptation across the system. Brown trout and the anadromous form, in particular, have experienced substantial declines in recent years and such treatments may threaten the genetic health of brown trout. This system represents a unique opportunity to understand (i) the impact of extreme bottlenecks on the genome of a species, (ii) how loss of genetic diversity influences immunity to parasites and (iii) the processes by which rapid adaptation occurs in genetically depauperate populations.