Gonzalez Elena G, Pedraza-Lara Carlos, Doadrio Ignacio
From the Departamento de Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales, MNCN-CSIC, José Gutiérrez Abascal, 2, Madrid 28006, Spain (Gonzalez, Pedraza-Lara, and Doadrio); and the Instituto de Biología, Universidad Nacional Autónoma de México,Tercer circuito s/n, Ciudad Universitaria, Coyoacán, Distrito Federal 04510, México (Pedraza-Lara).
J Hered. 2014 Sep-Oct;105(5):597-610. doi: 10.1093/jhered/esu034. Epub 2014 Jun 17.
The secondary freshwater fish fauna of the western-Iberian Peninsula basin is primarily restricted to local coastal streams, and man-made salt evaporation ponds, etc., which are susceptible to periodical flood and drought events. Despite its uniqueness in ecological adaptation to high saltwater tolerance, very little is known about this fauna's population dynamics and evolutionary history. The killifish, Aphanius baeticus (Cyprinodontidae) is an endemic species restricted to river basins on Spain's southern Atlantic coastline, considered as "Endangered." In this study, the genetic structure, diversity and historical demography of A. baeticus were analyzed using mitochondrial (cytochrome b, N=131) and nuclear (4 out of 19 microsatellites tested, N=288) markers across its distribution range. The phylogenetic and networking reconstruction revealed subtle phylogeographic structuring. A scattered expansion at the beginning of the interglacial periods, coupled with posterior events of extinction and colonization caused by periodical cycles of flooding, could explain the absence of well-defined phylogenetic relationships among populations. Moreover, very low genetic diversity values and a weak population differentiation were detected. We proposed that dispersals allowed by periodic floods connecting river drainages may have promoted a wide genetic exchange among populations and could have contributed to the current genetic relatedness of these populations.
伊比利亚半岛西部流域的次生淡水鱼类区系主要局限于当地的沿海溪流、人工盐蒸发池等，这些地方易受周期性洪水和干旱事件的影响。尽管该鱼类区系在生态适应高耐盐性方面具有独特性，但人们对其种群动态和进化历史知之甚少。鳉鱼（Aphanius baeticus，鲤齿科）是一种特有物种，仅分布于西班牙南部大西洋沿岸的流域，被视为“濒危”物种。在本研究中，利用线粒体（细胞色素b，N = 131）和核基因（19个微卫星标记中的4个，N = 288）标记，对分布范围内的巴氏鳉的遗传结构、多样性和历史种群动态进行了分析。系统发育和网络重建揭示了微妙的系统地理学结构。间冰期开始时的分散扩张，再加上周期性洪水导致的灭绝和定殖事件，可能解释了种群间缺乏明确的系统发育关系。此外，检测到极低的遗传多样性值和微弱的种群分化。我们认为，周期性洪水连接河流排水系统所允许的扩散可能促进了种群间广泛的基因交流，并可能导致了这些种群目前的遗传相关性。
