D'Aloia Cassidy C, Azodi Christina B, Sheldon Sallie P, Trombulak Stephen C, Ardren William R
Department of Ecology & Evolutionary Biology, University of Toronto , Toronto, Ontario , Canada ; Department of Biology, Middlebury College , Middlebury, VT , USA.
Department of Plant Biology, Michigan State University , East Lansing, MI , USA ; Department of Molecular Biology and Biochemistry, Middlebury College , Middlebury, VT , USA.
PeerJ. 2015 Oct 29;3:e1369. doi: 10.7717/peerj.1369. eCollection 2015.
The origin of sea lamprey (Petromyzon marinus) in Lake Champlain has been heavily debated over the past decade. Given the lack of historical documentation, two competing hypotheses have emerged in the literature. First, it has been argued that the relatively recent population size increase and concomitant rise in wounding rates on prey populations are indicative of an invasive population that entered the lake through the Champlain Canal. Second, recent genetic evidence suggests a post-glacial colonization at the end of the Pleistocene, approximately 11,000 years ago. One limitation to resolving the origin of sea lamprey in Lake Champlain is a lack of historical and current measures of population size. In this study, the issue of population size was explicitly addressed using nuclear (nDNA) and mitochondrial DNA (mtDNA) markers to estimate historical demography with genetic models. Haplotype network analysis, mismatch analysis, and summary statistics based on mtDNA noncoding sequences for NCI (479 bp) and NCII (173 bp) all indicate a recent population expansion. Coalescent models based on mtDNA and nDNA identified two potential demographic events: a population decline followed by a very recent population expansion. The decline in effective population size may correlate with land-use and fishing pressure changes post-European settlement, while the recent expansion may be associated with the implementation of the salmonid stocking program in the 1970s. These results are most consistent with the hypothesis that sea lamprey are native to Lake Champlain; however, the credibility intervals around parameter estimates demonstrate that there is uncertainty regarding the magnitude and timing of past demographic events.
在过去十年里，尚普兰湖海七鳃鳗（Petromyzon marinus）的起源一直备受争议。鉴于缺乏历史文献记录，文献中出现了两种相互竞争的假说。第一种观点认为，相对近期种群数量的增加以及随之而来的猎物受伤率上升表明这是一个通过尚普兰运河进入该湖的入侵种群。第二种观点认为，近期的基因证据表明在大约11000年前的更新世末期存在一次冰后期的种群定居。解决尚普兰湖海七鳃鳗起源问题的一个限制因素是缺乏历史和当前的种群数量测量数据。在本研究中，通过使用核（nDNA）和线粒体DNA（mtDNA）标记，利用遗传模型估计历史种群统计学，明确解决了种群数量问题。基于NCI（479 bp）和NCII（173 bp）的mtDNA非编码序列的单倍型网络分析、错配分析和汇总统计均表明近期种群扩张。基于mtDNA和nDNA的溯祖模型确定了两个潜在的种群统计学事件：种群数量下降，随后是非常近期的种群扩张。有效种群数量的下降可能与欧洲人定居后土地利用和捕鱼压力的变化有关，而近期的扩张可能与20世纪70年代鲑鱼放流计划的实施有关。这些结果与海七鳃鳗原产于尚普兰湖的假说最为一致；然而，参数估计周围的可信区间表明，过去种群统计学事件的规模和时间存在不确定性。
