Data from: Atypical panmixia in a European dolphin species (Delphinus delphis); implications for the evolution of diversity across oceanic boundaries.

Despite the scarcity of geographical barriers in the ocean environment, delphinid cetaceans often exhibit marked patterns of population structure on a regional scale. The European coastline is a prime example, with species exhibiting population structure across well defined environmental boundaries. Here we undertake a comprehensive population genetic study on the European common dolphin (Delphinus delphis, based on 492 samples and 15 loci) and establish that this species shows exceptional panmixia across most of the study range. We found differentiation only between the eastern and western Mediterranean, consistent with earlier studies, and here use Approximate Bayesian Computations to explore different scenarios to explain the observed pattern. Our results suggest that a recent population bottleneck likely contributed significantly to the differentiation of the Eastern Mediterranean population (in Greek waters). This interpretation is consistent with independent census data which suggests a sharp population decline in the recent past. The implication is that an unperturbed population may currently show panmixia across the full study range. This exception to the more typical pattern of population structure seen for other regional dolphin species (and for common dolphin populations elsewhere in the world) suggests particular ecological or life history traits distinct to this species in European waters.

尽管海洋环境中地理屏障稀缺，但海豚科鲸类往往在区域尺度上呈现出显著的种群结构模式。欧洲海岸线便是典型范例，相关物种在边界明确的环境分界处呈现出清晰的种群结构分化。本研究针对欧洲普通海豚（Delphinus delphis）开展全面的种群遗传学分析，共基于492份样本与15个基因座展开研究，证实该物种在绝大多数研究范围内呈现出极为罕见的随机交配（panmixia）模式。我们仅在地中海东部与西部种群间检测到遗传分化，这与此前的研究结果一致；本研究采用近似贝叶斯计算（Approximate Bayesian Computations）方法，构建多种演化场景以解释观测到的种群结构模式。研究结果表明，近期发生的种群瓶颈事件可能是导致地中海东部（希腊海域）种群分化的核心诱因。这一解读与独立的种群普查数据高度吻合——该数据显示该区域种群在近期经历了剧烈的数量下滑。这意味着，未受外界干扰的种群或许在整个研究区域内均呈现随机交配模式。这一现象与其他区域海豚类物种（以及全球其他海域的普通海豚种群）典型的种群结构模式形成鲜明反差，暗示欧洲海域的普通海豚具备独特的生态学或生活史特征。