Béres Beatrix, Kánainé Sipos Dóra, Müller Tamás, Staszny Ádám, Farkas Milán, Bakos Katalin, Orbán László, Urbányi Béla, Kovács Balázs
Department of Aquaculture, Szent István University , Gödöllő , Hungary.
Department of Aquaculture, Szent István University, Gödöllő, Hungary; Regional University Center of Excellence in Environmental Industry, Szent István University, Gödöllő, Hungary.
PeerJ. 2017 Feb 28;5:e2804. doi: 10.7717/peerj.2804. eCollection 2017.
Since three bullhead catfish species were introduced to Europe in the late 19th century, they have spread to most European countries. In Hungary, the brown bullhead () was more widespread in the 1970s-1980s, but the black bullhead () has gradually supplanted since their second introduction in 1980. The introgressive hybridization of the two species has been presumed based on morphological examinations, but it has not previously been supported by genetic evidence. In this study, 11 different Hungarian habitats were screened with a new species-specific nuclear genetic, duplex PCR based, marker system to distinguish the introduced catfish species, , and , as well as the hybrids of the first two. More than 460 specimens were analyzed using the above markers and additional mitochondrial sequence analyses were also conducted on >25% of the individuals from each habitat sampled. The results showed that only 7.9% of the specimens from two habitats belonged to , and 92.1% were classified as of all habitats, whereas the presence of was not detected. Two specimens (>0.4%) showed the presence of both nuclear genomes and they were identified as hybrids of . An additional two individuals showed contradicting results from the nuclear and mitochondrial assays as a sign of a possible footprint of introgressive hybridization that might have happened two or more generations before. Surprisingly, the level of hybridization was much smaller than expected based on the analyses of the North American continent's indigenous stock from the hybrid zones. This phenomenon has been observed in several invasive fish species and it is regarded as an added level of complexity in the management of their rapid adaptation.
自19世纪末三种鲶鱼被引入欧洲以来，它们已扩散到大多数欧洲国家。在匈牙利，褐首鲶（）在20世纪70年代至80年代分布更广，但自1980年再次引入以来，黑首鲶（）已逐渐取而代之。基于形态学检查推测这两个物种存在渐渗杂交，但此前尚未得到遗传证据的支持。在本研究中，使用一种基于双重PCR的新的物种特异性核基因标记系统，对匈牙利11个不同栖息地进行筛选，以区分引入的鲶鱼物种、和，以及前两者的杂交种。使用上述标记对460多个样本进行了分析，并对每个栖息地超过25%的个体进行了额外的线粒体序列分析。结果表明，来自两个栖息地的样本中只有7.9%属于，所有栖息地中92.1%被归类为，而未检测到的存在。两个样本（>0.4%）显示同时存在两种核基因组，它们被鉴定为的杂交种。另外两个个体的核分析和线粒体分析结果相互矛盾，表示可能存在两代或多代以前发生的渐渗杂交痕迹。令人惊讶的是，杂交水平比基于对北美大陆杂交区本土种群的分析所预期的要小得多。这种现象在几种入侵鱼类中都有观察到，被认为是它们快速适应管理中增加的一个复杂层面。
