Converse Paul E, Kuchta Shawn R, Hauswaldt J Susanne, Roosenburg Willem M
Department of Biological Sciences, Ohio University, Athens, Ohio, United States of America.
Ohio Center for Ecology and Evolutionary Studies, Ohio University, Athens, Ohio, United States of America.
PLoS One. 2017 Aug 9;12(8):e0181898. doi: 10.1371/journal.pone.0181898. eCollection 2017.
Diamondback terrapins (Malaclemys terrapin) were a popular food item in early twentieth century America, and were consumed in soup with sherry. Intense market demand for terrapin meat resulted in population declines, notably along the Atlantic seaboard. Efforts to supply terrapins to markets resulted in translocation events, as individuals were moved about to stock terrapin farms. However, in 1920 the market for turtle soup buckled with the enactment of the eighteenth amendment to the United States' Constitution-which initiated the prohibition of alcoholic drinks-and many terrapin fisheries dumped their stocks into local waters. We used microsatellite data to show that patterns of genetic diversity along the terrapin's coastal range are consistent with historical accounts of translocation and cultivation activities. We identified possible instances of human-mediated dispersal by estimating gene flow over historical and contemporary timescales, Bayesian model testing, and bottleneck tests. We recovered six genotypic clusters along the Gulf and Atlantic coasts with varying degrees of admixture, including increased contemporary gene flow from Texas to South Carolina, from North Carolina to Maryland, and from North Carolina to New York. In addition, Bayesian models incorporating translocation events outperformed stepping-stone models. Finally, we were unable to detect population bottlenecks, possibly due to translocation reintroducing genetic diversity into bottlenecked populations. Our data suggest that current patterns of genetic diversity in the terrapin were altered by the demand for turtle soup followed by the enactment of alcohol prohibition. In addition, our study shows that population genetic tools can elucidate metapopulation dynamics in taxa with complex genetic histories impacted by anthropogenic activities.
菱斑龟（菱斑龟属）在20世纪初的美国是一种受欢迎的食物，常被用来与雪利酒一起炖汤食用。对菱斑龟肉的强烈市场需求导致其数量下降，尤其是在大西洋沿岸。为了满足市场对菱斑龟的供应，人们进行了迁移活动，将菱斑龟转移到各地以充实龟场。然而，1920年，随着美国宪法第十八条修正案的颁布——该修正案开始禁止酒精饮料——龟汤市场崩溃，许多菱斑龟养殖场将龟群倾倒到当地水域。我们利用微卫星数据表明，菱斑龟沿海分布范围内的遗传多样性模式与迁移和养殖活动的历史记录一致。我们通过估计历史和当代时间尺度上的基因流动、贝叶斯模型测试和瓶颈测试，确定了可能的人类介导扩散实例。我们在墨西哥湾和大西洋沿岸发现了六个基因型簇，它们的混合程度各不相同，包括从德克萨斯州到南卡罗来纳州、从北卡罗来纳州到马里兰州以及从北卡罗来纳州到纽约州的当代基因流动增加。此外，纳入迁移事件的贝叶斯模型比踏脚石模型表现更好。最后，我们无法检测到种群瓶颈，这可能是由于迁移将遗传多样性重新引入了瓶颈种群。我们的数据表明，菱斑龟当前的遗传多样性模式因龟汤需求以及随后的禁酒令而改变。此外，我们的研究表明，种群遗传工具可以阐明受人为活动影响的具有复杂遗传历史的类群中的集合种群动态。
