Domingues Vera S, Faria Cláudia, Stefanni Sergio, Santos Ricardo S, Brito Alberto, Almada Vitor C
Instituto Superior de Psicologia Aplicada, Unidade de Investigação em Eco-Etologia, R. Jardim do Tabaco 34, 1149-041 Lisboa, Portugal.
Mol Ecol. 2007 Sep;16(17):3592-605. doi: 10.1111/j.1365-294X.2007.03405.x.
Coryphoblennius galerita is a small intertidal fish with a wide distribution and limited dispersal ability, occurring in the northeastern Atlantic and Mediterranean. In this study, we examined Atlantic and Mediterranean populations of C. galerita to assess levels of genetic divergence across populations and to elucidate historical and contemporary factors underlying the distribution of the genetic variability. We analyse three mitochondrial and one nuclear marker and 18 morphological measurements. The combined dataset clearly supports the existence of two groups of C. galerita: one in the Mediterranean and another in the northeastern Atlantic. The latter group is subdivided in two subgroups: Azores and the remaining northeastern Atlantic locations. Divergence between the Atlantic and the Mediterranean can be the result of historical isolation between the populations of the two basins during the Pleistocene glaciations. Present-day barriers such as the Gibraltar Strait or the 'Almeria-Oran jet' are also suggested as responsible for this isolation. Our results show no signs of local extinctions during the Pleistocene glaciations, namely at the Azores, and contrast with the biogeographical pattern that has been observed for Atlantic-Mediterranean warm-water species, in which two groups of populations exist, one including the Mediterranean and the Atlantic coast of western Europe, and another encompassing the western tropical coast of Africa and the Atlantic islands of the Azores, Madeira and Canaries. Species like C. galerita that tolerate cooler waters, may have persisted during the Pleistocene glaciations in moderately affected locations, thus being able to accumulate genetic differences in the more isolated locations such as the Azores and the Mediterranean. This study is one of the first to combine morphological and molecular markers (mitochondrial and nuclear) with variable rates of molecular evolution to the study of the relationships of the Atlantic and Mediterranean populations of a cool-water species.
加氏冠鳚是一种小型潮间带鱼类，分布广泛但扩散能力有限，见于东北大西洋和地中海。在本研究中，我们对加氏冠鳚的大西洋和地中海种群进行了检测，以评估种群间的遗传分化水平，并阐明遗传变异分布背后的历史和当代因素。我们分析了三个线粒体标记、一个核标记以及18项形态学测量指标。综合数据集明确支持加氏冠鳚存在两组：一组在地中海，另一组在东北大西洋。后一组又细分为两个亚组：亚速尔群岛和东北大西洋的其他地区。大西洋和地中海之间的分化可能是更新世冰川作用期间两个盆地种群历史隔离的结果。直布罗陀海峡或“阿尔梅里亚-奥兰急流”等当今的屏障也被认为是造成这种隔离的原因。我们的结果显示在更新世冰川作用期间没有局部灭绝的迹象，即在亚速尔群岛，这与大西洋-地中海暖水物种所观察到的生物地理模式形成对比，在该模式中存在两组种群，一组包括地中海和西欧大西洋海岸，另一组包括非洲西部热带海岸以及亚速尔群岛、马德拉群岛和加那利群岛等大西洋岛屿。像加氏冠鳚这样能耐受较冷水域的物种，可能在更新世冰川作用期间在受影响程度适中的地点得以存续，从而能够在诸如亚速尔群岛和地中海等更为孤立的地点积累遗传差异。本研究是首批将形态学和分子标记（线粒体和核标记）与分子进化可变速率相结合来研究冷水物种大西洋和地中海种群关系的研究之一。
