Human activity has caused a deterioration in the health and population size of riverine species; thus, public policies have been implemented to mitigate the anthropogenic impacts of water use, watercourse transformation, and pollution. We studied the Maipo River Basin, one of the most polluted with untreated wastewater in Chile, for a period of 12 years (2007‐2019). Since the implementation of new public policies, including the operation of a wastewater collector (2012), the Maipo River Basin is currently much less polluted by untreated water than before. To analyze the impact of wastewater reduction in this river basin, we studied the native silverside (Basilichthys microlepidotus), which inhabits both polluted and unpolluted areas of the river basin. Previous studies reported the overexpression of the ornithine decarboxylase (odc) gene, heterozygote deficit, and high frequency of a homozygote odc genotype in silverside populations that inhabit wastewater‐polluted sites, suggesting a phenotypic change and genotypic selection in response to pollution. Here, a population affected and another population unaffected by wastewater were studied before and after implementing the wastewater collector. The physicochemical data of water samples, changes in odc expression and microsatellite variability, and odc genotype frequencies were analyzed. The results showed physicochemical changes in the affected site before and after the operation of the wastewater collector. The microsatellite loci showed no changes in either population. The odc expression in the affected site was higher before the operation of the wastewater collector. Significant changes in the genotype frequencies of the odc gene before and after the wastewater collector operation were detected only at the affected site, wherein the homozygous dominant genotype decreased from >59% to <25%. Our results suggest that public policies aimed at mitigating aquatic pollution can indirectly affect both gene expression and genotype frequencies of important functional genes.

中文翻译：

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本地银边小鳞鱼鸟氨酸脱羧酶基因表达和基因型频率的时间变化：公共政策实施对废水减少的影响。

人类活动导致河流物种的健康状况和种群规模恶化；因此，已经实施了公共政策来减轻用水、河道改造和污染的人为影响。我们对迈波河流域进行了为期 12 年（2007-2019 年）的研究，该河流域是智利未经处理废水污染最严重的地区之一。自从实施新的公共政策，包括污水收集器的运行（2012年）以来，麦坡河流域目前未经处理的水污染比以前少得多。为了分析该流域废水减少的影响，我们研究了栖息在流域污染和未污染地区的本地银鱼（ Basilichthys microlepidotus ）。先前的研究报道了居住在废水污染地点的银鳅种群中鸟氨酸脱羧酶（ odc ）基因的过度表达、杂合子缺陷和纯合子odc基因型的高频率，表明针对污染的表型变化和基因型选择。在这里，我们对安装废水收集器之前和之后受废水影响的人群和未受废水影响的人群进行了研究。分析了水样的理化数据、odc表达和微卫星变异的变化以及odc基因型频率。结果显示了污水收集器运行前后受影响地点的物理化学变化。微卫星位点显示这两个群体均没有变化。在废水收集器运行之前，受影响地点的odc表达较高。仅在受影响地点检测到废水收集器运行前后odc基因的基因型频率发生显着变化，其中纯合显性基因型从>59%下降到<25%。我们的结果表明，旨在减轻水生污染的公共政策可以间接影响重要功能基因的基因表达和基因型频率。