Aglieri Giorgio, Papetti Chiara, Zane Lorenzo, Milisenda Giacomo, Boero Ferdinando, Piraino Stefano
Dipartimento di Scienze e Tecnologie Biologiche e Ambientali (DiSTeBA), Università del Salento, Lecce, Italy; Consorzio Nazionale Interuniversitario per le Scienze del Mare (CoNISMa), Roma, Italy.
Consorzio Nazionale Interuniversitario per le Scienze del Mare (CoNISMa), Roma, Italy; Dipartimento di Biologia, Università di Padova, Padova, Italy; Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany.
PLoS One. 2014 Jun 30;9(6):e99647. doi: 10.1371/journal.pone.0099647. eCollection 2014.
Genetic drift and non-random mating seldom influence species with large breeding populations and high dispersal potential, characterized by unstructured gene pool and panmixia at a scale lower than the minimum dispersal range of individuals. In the present study, a set of nine microsatellite markers was developed and used to investigate the spatio-temporal genetic patterns of the holoplanktonic jellyfish Pelagia noctiluca (Scyphozoa) in the Southern Tyrrhenian Sea. Homozygote excess was detected at eight loci, and individuals exhibited intra-population relatedness higher than expected by chance in at least three samples. This result was supported by the presence of siblings in at least 5 out 8 samples, 4 of which contained full-sib in addition to half-sib dyads. Having tested and ruled out alternative explanations as null alleles, our results suggest the influence of reproductive and behavioural features in shaping the genetic structure of P. noctiluca, as outcomes of population genetics analyses pointed out. Indeed, the genetic differentiation among populations was globally small but highlighted: a) a spatial genetic patchiness uncorrelated with distance between sampling locations, and b) a significant genetic heterogeneity between samples collected in the same locations in different years. Therefore, despite its extreme dispersal potential, P. noctiluca does not maintain a single homogenous population, but rather these jellyfish appear to have intra-bloom localized recruitment and/or individual cohesiveness, whereby siblings more likely swarm together as a single group and remain close after spawning events. These findings provide the first evidence of family structures and consequent genetic patchiness in a species with highly dispersive potential throughout its whole life cycle, contributing to understanding the patterns of dispersal and connectivity in marine environments.
遗传漂变和非随机交配很少影响具有大量繁殖种群和高扩散潜力的物种，这些物种的基因库无结构，且在低于个体最小扩散范围的尺度上呈现随机交配。在本研究中，开发了一组九个微卫星标记，并用于研究第勒尼安海南部全浮游水母夜光游水母（钵水母纲）的时空遗传模式。在八个位点检测到纯合子过剩，并且在至少三个样本中，个体表现出高于随机预期的种群内亲缘关系。这一结果得到了至少8个样本中有5个样本存在同胞关系的支持，其中4个样本除了半同胞对之外还包含全同胞。在测试并排除了作为无效等位基因的其他解释后，我们的结果表明，如群体遗传学分析结果所指出的，生殖和行为特征对夜光游水母遗传结构的形成有影响。事实上，种群间的遗传分化总体较小，但突出显示出：a）与采样地点之间的距离无关的空间遗传斑块，以及b）在不同年份同一地点采集的样本之间存在显著的遗传异质性。因此，尽管夜光游水母具有极高的扩散潜力，但它并没有维持单一的同质种群，而是这些水母似乎在水华期间有局部补充和/或个体聚集性，即同胞更有可能作为一个群体聚集在一起，并在产卵事件后保持紧密联系。这些发现首次证明了在一个在其整个生命周期中具有高度扩散潜力的物种中存在家族结构以及随之而来的遗传斑块，有助于理解海洋环境中的扩散和连通模式。
