Hawai'i Institute of Marine Biology, University of Hawai'i, Mānoa, PO Box 1346, Kāne'ohe, HI 96744, USA.
Mol Ecol. 2013 Jul;22(14):3721-36. doi: 10.1111/mec.12335. Epub 2013 Jun 20.
Patterns of isolation by distance are uncommon in coral populations. Here, we depart from historical trends of large-scale, geographical genetic analyses by scaling down to a single patch reef in Kāne'ohe Bay, Hawai'i, USA, and map and genotype all colonies of the coral, Pocillopora damicornis. Six polymorphic microsatellite loci were used to assess population genetic and clonal structure and to calculate individual colony pairwise relatedness values. Our results point to an inbred, highly clonal reef (between 53 and 116 clonal lineages of 2352 genotyped colonies) with a much skewed genet frequency distribution (over 70% of the reef was composed of just seven genotypes). Spatial autocorrelation analyses revealed that corals found close together on the reef were more genetically related than corals further apart. Spatial genetic structure disappears, however, as spatial scale increases and then becomes negative at the largest distances. Stratified, random sampling of three neighbouring reefs confirms that reefs are demographically open and inter-reef genetic structuring was not detected. Attributing process to pattern in corals is complicated by their mixed reproductive strategies. Separate autocorrelation analyses, however, show that the spatial distribution of both clones and nonclones contributes to spatial genetic structure. Overall, we demonstrate genetic structure on an intrareef scale and genetic panmixia on an inter-reef scale indicating that, for P. damicornis, the effect of small- and large-scale dispersal processes on genetic diversity are not the same. By starting from an interindividual, intrareef level before scaling up to an inter-reef level, this study demonstrates that isolation-by-distance patterns for the coral P. damicornis are limited to small scales and highlights the importance of investigating genetic patterns and ecological processes at multiple scales.
距离隔离模式在珊瑚种群中并不常见。在这里，我们背离了大规模地理遗传分析的历史趋势，将研究范围缩小到美国夏威夷卡内奥赫湾的一个单一的礁盘，并绘制和基因型所有的珊瑚，Pocillopora damicornis。使用六个多态微卫星基因座来评估种群遗传和克隆结构，并计算单个珊瑚丛的个体间亲缘关系值。我们的结果表明，这是一个近交的、高度克隆的珊瑚礁（在 2352 个基因型的珊瑚丛中，有 53 到 116 个克隆谱系），其遗传频率分布严重偏斜（超过 70%的珊瑚礁由仅仅七种基因型组成）。空间自相关分析表明，在珊瑚礁上彼此靠近的珊瑚比相距较远的珊瑚更具有遗传相关性。然而，随着空间尺度的增加，空间遗传结构消失，然后在最大距离处变为负相关。对三个相邻礁盘的分层随机抽样证实，礁盘在人口统计学上是开放的，并且没有检测到礁盘之间的遗传结构。珊瑚的混合繁殖策略使其将过程归因于模式变得复杂。然而，单独的自相关分析表明，克隆和非克隆的空间分布都有助于空间遗传结构。总的来说，我们在礁内尺度上展示了遗传结构，在礁间尺度上展示了遗传混合，表明对于 P. damicornis 而言，小尺度和大尺度扩散过程对遗传多样性的影响是不同的。通过从个体内、礁内尺度开始，然后扩展到礁间尺度，本研究表明，P. damicornis 的距离隔离模式仅限于小尺度，并强调了在多个尺度上调查遗传模式和生态过程的重要性。
