Bourret Vincent, Couture Patrice, Campbell Peter G C, Bernatchez Louis
Institut National de la Recherche Scientifique, Centre Eau, Terre et Environnement, Québec, Canada.
Aquat Toxicol. 2008 Jan 20;86(1):76-90. doi: 10.1016/j.aquatox.2007.10.003. Epub 2007 Oct 12.
Depending on such factors as the intensity and duration of the exposure, and the genetic diversity and connectedness of the starting population, exposure to elevated metal concentrations can result in population level alterations such as demographic bottlenecks or metal-induced selection. These processes can be revealed using a population genetic approach, and have important implications with respect to population persistence. The main objective of this study was to examine the role of metal contamination in driving evolutionary changes by documenting patterns of genetic diversity within and among populations of wild yellow perch (Perca flavescens) in two major mining regions that have been subjected to metal emissions from smelters for at least 80 years; Rouyn-Noranda, Québec and Sudbury, Ontario. Yellow perch populations from ten lakes representing a gradient of metal contamination in each of the two lake systems were evaluated concurrently to reveal relationships between metal contamination and genetic diversity. These replicated sympatric observations allowed us to evaluate correlations and infer causal relationships between metal exposure and evolutionary responses in this species. Within-population gene diversity over all loci was negatively correlated with liver cadmium contamination (P<0.001; r(2)=0.47). Similarly, a negative correlation between gene diversity and liver copper contamination was observed at a single locus (Pfla L1, P=0.005; r(2)=0.33), suggesting a local effect of copper contamination. Internal relatedness, an index of individual diversity, presented the opposite tendency as the more contaminated individuals were more diverse than were the less contaminated ones in contaminated and reference populations. Our results thus suggest that the selective response to contamination has been large enough to substantially reduce the within-population genetic diversity, despite the fact that the less inbred individuals may be favoured by selection within any given population. Overall, our results reveal that >50 years of metal contamination have significantly impacted patterns of genetic diversity observed among populations of wild yellow perch in mining areas and as such, may have affected the capacity of populations to respond to future environmental changes.
根据暴露的强度和持续时间、起始种群的遗传多样性和连通性等因素，暴露于升高的金属浓度可能导致种群水平的变化，如人口瓶颈或金属诱导的选择。这些过程可以通过种群遗传学方法揭示，并且对种群的持久性具有重要意义。本研究的主要目的是通过记录野生黄鲈（Perca flavescens）种群内部和种群之间的遗传多样性模式，来研究金属污染在推动进化变化中的作用。这两个主要矿区已受到冶炼厂至少80年的金属排放影响，分别是魁北克省的鲁安 - 诺兰达和安大略省的萨德伯里。同时评估了来自两个湖泊系统中代表金属污染梯度的十个湖泊的黄鲈种群，以揭示金属污染与遗传多样性之间的关系。这些重复的同域观察使我们能够评估相关性，并推断该物种中金属暴露与进化反应之间的因果关系。所有位点的种群内基因多样性与肝脏镉污染呈负相关（P<0.001；r(2)=0.47）。同样，在单个位点（Pfla L1）观察到基因多样性与肝脏铜污染之间存在负相关（P = 0.005；r(2)=0.33），表明铜污染具有局部效应。内部亲缘关系是个体多样性的一个指标，呈现出相反的趋势，因为在受污染和参考种群中，污染程度较高的个体比污染程度较低的个体具有更多样性。因此，我们的结果表明，尽管在任何给定种群中选择可能有利于近交程度较低的个体，但对污染的选择性反应已经足够大，足以显著降低种群内的遗传多样性。总体而言，我们的结果表明，超过50年的金属污染已对矿区野生黄鲈种群之间观察到的遗传多样性模式产生了显著影响，因此可能已经影响了种群应对未来环境变化的能力。
