Population Ecology Group, Institut Mediterrani d'Estudis Avançats IMEDEA (CSIC-UIB), Esporles, Mallorca, Spain.
PLoS One. 2013 Aug 12;8(8):e70711. doi: 10.1371/journal.pone.0070711. eCollection 2013.
Dispersal is critically linked to the demographic and evolutionary trajectories of populations, but in most seabird species it may be difficult to estimate. Using molecular tools, we explored population structure and the spatial dispersal pattern of a highly pelagic but philopatric seabird, the Cory's shearwater Calonectris diomedea. Microsatellite fragments were analysed from samples collected across almost the entire breeding range of the species. To help disentangle the taxonomic status of the two subspecies described, the Atlantic form C. d. borealis and the Mediterranean form C. d. diomedea, we analysed genetic divergence between subspecies and quantified both historical and recent migration rates between the Mediterranean and Atlantic basins. We also searched for evidence of isolation by distance (IBD) and addressed spatial patterns of gene flow. We found a low genetic structure in the Mediterranean basin. Conversely, strong genetic differentiation appeared in the Atlantic basin. Even if the species was mostly philopatric (97%), results suggest recent dispersal between basins, especially from the Atlantic to the Mediterranean (aprox. 10% of migrants/generation across the last two generations). Long-term gene flow analyses also suggested an historical exchange between basins (about 70 breeders/generation). Spatial analysis of genetic variation indicates that distance is not the main factor in shaping genetic structure in this species. Given our results we recommend gathering more data before concluded whether these taxa should be treated as two species or subspecies.
扩散与种群的人口和进化轨迹密切相关，但在大多数海鸟物种中，它可能难以估计。使用分子工具，我们研究了高度洄游但恋家的海鸟——冠毛小海雀 Calonectris diomedea 的种群结构和空间扩散模式。从该物种几乎整个繁殖范围内采集的样本中分析了微卫星片段。为了帮助理清描述的两个亚种的分类地位，即大西洋形式 C. d. borealis 和地中海形式 C. d. diomedea，我们分析了亚种之间的遗传差异，并量化了地中海和大西洋盆地之间的历史和近期迁移率。我们还寻找了隔离距离（IBD）的证据，并解决了基因流动的空间模式。我们在地中海盆地发现了低遗传结构。相反，在大西洋盆地出现了强烈的遗传分化。即使该物种主要是恋家的（97%），结果表明最近在盆地之间发生了扩散，特别是从大西洋到地中海（在过去两代中，每代约有 10%的移民）。长期基因流动分析还表明了两个盆地之间的历史交流（大约每代 70 个繁殖者）。遗传变异的空间分析表明，距离不是该物种形成遗传结构的主要因素。考虑到我们的结果，我们建议在得出这些分类单元是否应被视为两个物种或亚种之前，收集更多的数据。
