Contemporary genetic structure and postglacial demographic history of the black scorpionfish, Scorpaena porcus, in the Mediterranean and the Black Seas

Understanding the distribution of genetic diversity in the light of past demographic events linked with climatic shifts will help to forecast evolutionary trajectories of ecosystems within the current context of climate change. In this study, mitochondrial sequences and microsatellite loci were analysed using traditional population genetic approaches together with Bayesian dating and the more recent approximate Bayesian computation scenario testing. The genetic structure and demographic history of a commercial fish, the black scorpionfish, Scorpaena porcus, was investigated throughout the Mediterranean and Black Seas. The results suggest that the species recently underwent population expansions, in both seas, likely concomitant with the warming period following the Last Glacial Maximum, 20 000 years ago. A weak contemporaneous genetic differentiation was identified between the Black Sea and the Mediterranean Sea. However, the genetic diversity was similar for populations of the two seas, suggesting a high number of colonizers entered the Black Sea during the interglacial period and/or the presence of a refugial population in the Black Sea during the glacial period. Finally, within seas, an east/west genetic differentiation in the Adriatic seems to prevail, whereas the Black Sea does not show any structured spatial genetic pattern of its population. Overall, these results suggest that the Black Sea is not that isolated from the Mediterranean, and both seas revealed similar evolutionary patterns related to climate change and changes in sea level.

结合与气候变迁相关的既往种群动态事件解析遗传多样性的分布格局，将有助于在当前气候变化背景下预测生态系统的演化轨迹。本研究采用传统种群遗传学分析方法，结合贝叶斯定年（Bayesian dating）以及新兴的近似贝叶斯计算（approximate Bayesian computation）情景检验策略，对线粒体序列与微卫星位点（microsatellite loci）进行了分析。研究针对地中海与黑海全域分布的商业性鱼类——黑鲉（Scorpaena porcus），解析了其种群遗传结构与种群动态历史。结果显示，该物种在两大海域均经历了近期种群扩张事件，这大概率与2万年前末次冰盛期（Last Glacial Maximum）后的升温阶段相吻合。研究发现黑海与地中海之间存在微弱的当代遗传分化。但两大海域的种群遗传多样性水平并无显著差异，这表明在间冰期阶段有大量拓殖种群迁入黑海，或黑海在冰期存在避难所种群。此外，在海域内部，亚得里亚海（Adriatic）种群呈现显著的东西向遗传分化格局，而黑海种群则未表现出任何结构化的空间遗传模式。综合来看，本研究结果表明黑海与地中海的种群隔离程度并不高，且两大海域均呈现出与气候变化及海平面变化相关的相似演化模式。