From Late Miocene to Holocene: Processes of Differentiation within the Telestes Genus (Actinopterygii: Cyprinidae)

Investigating processes and timing of differentiation of organisms is critical in the understanding of the evolutionary mechanisms involved in microevolution, speciation, and macroevolution that generated the extant biodiversity. From this perspective, the Telestes genus is of special interest: the Telestes species have a wide distribution range across Europe (from the Danubian district to Mediterranean districts) and have not been prone to translocation. Molecular data (mtDNA: 1,232 bp including the entire Cyt b gene; nuclear genome: 11 microsatellites) were gathered from 34 populations of the Telestes genus, almost encompassing the entire geographic range. Using several phylogenetic and molecular dating methods interpreted in conjunction with paleoclimatic and geomorphologic evidence, we investigated the processes and timing of differentiation of the Telestes lineages. The observed genetic structure and diversity were largely congruent between mtDNA and microsatellites. The Messinian Salinity Crisis (Late Miocene) seems to have played a major role in the speciation processes of the genus. Focusing on T. souffia, a species occurring in the Danube and Rhone drainages, we were able to point out several specific events from the Pleistocene to the Holocene that have likely driven the differentiation and the historical demography of this taxon. This study provides support for an evolutionary history of dispersal and vicariance with unprecedented resolution for any freshwater fish in this region.探究生物分化的过程与时间节点，对于理解驱动现存生物多样性形成的微演化、物种形成及宏演化相关机制，具有至关重要的意义。基于此研究视角，泰莱斯鱼属（Telestes）具有特殊的研究价值：该属鱼类在欧洲分布范围广泛，涵盖多瑙河流域至地中海流域，且未发生人为易位引种事件。本研究从泰莱斯鱼属的34个种群中采集了分子数据：线粒体DNA（mtDNA）片段总长1232碱基对，包含完整的细胞色素b（Cyt b）基因；核基因组方面则包含11个微卫星（microsatellites）位点，采样范围几乎覆盖该属的全部地理分布区。本研究结合古气候与地貌学证据，采用多种系统发育分析及分子定年方法，对泰莱斯鱼属各演化支的分化过程与时间节点展开了探究。观测结果显示，线粒体DNA与微卫星标记所揭示的遗传结构及遗传多样性高度一致。墨西拿盐度危机（Messinian Salinity Crisis，晚中新世）似乎对该属的物种形成过程起到了核心驱动作用。本研究进一步聚焦于分布于多瑙河与罗讷河水系的索氏泰莱斯鱼（T. souffia），明确了更新世至全新世期间多个可能驱动该类群分化与历史种群动态的特异性事件。本研究为该区域淡水鱼类的扩散-隔离分化演化历史提供了目前同类研究中前所未有的高分辨率证据支撑。