Population genetics of three threatened catfish species in heterogeneous environments of the Cauca River, Colombia

ABSTRACT Neotropical catfishes Ageneiosus pardalis, Pimelodus grosskopfii and Sorubim cuspicaudus are migratory fishes of commercial importance that exhibit decreasing populations due to overfishing and other anthropic interventions. This study used species-specific microsatellite loci to test the hypothesis that threatened fish populations show genetic vulnerability signs and are genetically structured in the middle and lower sections of the Cauca River. The studied species exhibit genetic diversity levels higher than the average values reported for Neotropical Siluriformes; however, they seem to have suffered recent bottlenecks and they present significant endogamy levels that are higher for the critically endangered catfish P. grosskopfii. Furthermore, both Ageneiosus pardalis and S. cuspicaudus are each formed by one genetic group, while Pimelodus grosskopfii comprises two coexisting genetic groups. The information obtained in this study is useful for the decision making in management plans that are appropriate for the sustainability of these three species populations within the proposal for the expansion of the hydroelectric development and other anthropic activities.

摘要：新热带区鲶形目（Siluriformes）鱼类斑身无齿鲶（Ageneiosus pardalis）、格氏油鲶（Pimelodus grosskopfii）与尖尾犁头鲶（Sorubim cuspicaudus）均为兼具商业价值的洄游性鱼类，其种群因过度捕捞及其他人类活动干扰而持续下降。本研究采用物种特异性微卫星位点（microsatellite loci），检验“受胁鱼类种群存在遗传脆弱性特征，且在考卡河中下游存在遗传结构分化”这一假说。结果显示，上述研究物种的遗传多样性水平高于新热带区鲶形目（Siluriformes）鱼类的平均报道值，但均近期经历了种群瓶颈事件，且存在显著的近交现象；其中被列为极危物种的格氏油鲶（P. grosskopfii）近交程度更高。进一步分析表明，斑身无齿鲶与尖尾犁头鲶各自仅包含单一遗传类群，而格氏油鲶则包含两个共存的遗传类群。本研究获取的相关数据可为制定合理的物种管理方案提供决策依据，以在水电开发扩张及其他人类活动的背景下，保障这三个物种种群的可持续存续。