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相对匮乏，但海豚科鲸类（delphinid cetaceans）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例证，该区域的海豚科鲸类种群结构清晰对应于明确划分的环境边界。本研究针对欧洲真海豚（Delphinus delphis）开展了全面的种群遗传学研究（共纳入492份样本、15个基因座），证实该物种在绝大多数研究区域内呈现出罕见的泛交（panmixia）现象。本研究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；同时我们采用近似贝叶斯计算（Approximate Bayesian Computations）方法，探索了多种可解释该观测模式的演化情景。研究结果显示，近期发生的种群瓶颈效应很可能是导致东地中海（希腊海域）种群分化的关键诱因。该推论与独立开展的种群普查数据相吻合——后者显示该种群在近期经历了急剧的数量衰减。这意味着在未受外界干扰的前提下，该种群目前在整个研究区域内应呈现泛交现象。相较于其他区域海豚物种（以及全球其他海域的真海豚种群）所呈现的典型种群结构模式，本研究的结果属于特例，这暗示欧洲海域的真海豚种群拥有独特的生态或生活史特征。