Wirgin I, Maceda L, Stabile J, Mesing C
Institute of Environmental Medicine, New York University Medical Center, Tuxedo, NY 10987, USA.
Mol Ecol. 1997 Oct;6(10):907-16. doi: 10.1046/j.1365-294x.1997.00271.x.
Striped bass Morone saxatilis populations in drainages along the Gulf of Mexico coast (Gulf) were depleted in the 1950s and 1960s, probably because of anthropogenic influences. It is believed that only the Apalachicola-Chattahoochee-Flint (A-C-F) river system continually supported a naturally reproducing population of Gulf lineage. Striped bass juveniles of Atlantic coast (Atlantic) ancestry were introduced to restore population abundances in the A-C-F from the late 1960s to the mid 1970s and in many other Gulf rivers from the 1960s to the present. We previously identified mtDNA polymorphisms that were unique to approximately 60% of striped bass from the A-C-F and which confirmed the continued successful natural reproduction of striped bass of Gulf maternal ancestry within the system. However, the genetic relatedness of the extant A-C-F population to 'pure' Gulf striped bass was not addressed. In this study, we determined the frequency of a diagnostic mtDNA XbaI polymorphism in samples of 'pure' Gulf striped bass that were collected from the A-C-F prior to the introduction of Atlantic fish, that were obtained from museum collections, and that were originally preserved in formalin. PCR primers were developed that allowed for amplification of a 191-bp mtDNA fragment that contained the diagnostic XbaI restriction site. Using RFLP and direct sequence analyses of the PCR amplicons, we found no significant differences in mtDNA XbaI genotype frequencies between the archived samples and extant A-C-F samples collected over a 15-year period. This indicates that significant maternally mediated introgression of Atlantic mtDNA genomes into the A-C-F gene pool has not occurred. Additionally, we found no evidence of the unique Gulf mtDNA genotype in striped bass from extant populations in Texas, Louisiana and the Mississippi River. These results highlight the importance of the A-C-F as a repository of striped bass to restore extirpated Gulf populations and the potential use of museum collections in retrospective population studies.
20世纪50年代和60年代，墨西哥湾沿岸流域的条纹鲈（Morone saxatilis）种群数量锐减，这可能是人为影响所致。据信，只有阿巴拉契科拉-查塔胡奇-弗林特（A-C-F）河系持续维持着墨西哥湾谱系的自然繁殖种群。从20世纪60年代末到70年代中期，引入了大西洋沿岸（大西洋）血统的条纹鲈幼鱼，以恢复A-C-F河系中的种群数量，从20世纪60年代至今，也在许多其他墨西哥湾河流中引入了这种幼鱼。我们之前鉴定出了mtDNA多态性，这些多态性约60%的A-C-F条纹鲈所特有，证实了该河系中墨西哥湾母系血统条纹鲈的自然繁殖持续成功。然而，现存的A-C-F种群与“纯种 ”墨西哥湾条纹鲈的遗传相关性尚未得到研究。在本研究中，我们测定了“纯种 ”墨西哥湾条纹鲈样本中一种诊断性mtDNA XbaI多态性的频率，这些样本是在引入大西洋鱼类之前从A-C-F河系采集的，取自博物馆藏品，最初保存在福尔马林中。开发了PCR引物，用于扩增包含诊断性XbaI限制性酶切位点的191-bp mtDNA片段。通过对PCR扩增产物进行RFLP和直接序列分析，我们发现存档样本与15年间采集的现存A-C-F样本之间，mtDNA XbaI基因型频率没有显著差异。这表明大西洋mtDNA基因组没有通过母系介导大量渗入A-C-F基因库。此外，我们在得克萨斯州、路易斯安那州和密西西比河现存种群的条纹鲈中，没有发现独特的墨西哥湾mtDNA基因型的证据。这些结果凸显了A-C-F河系作为恢复已灭绝的墨西哥湾条纹鲈种群的条纹鲈储存库的重要性，以及博物馆藏品在回顾性种群研究中的潜在用途。
