Data from: Genotypic diversity and spatial-temporal distribution of Symbiodinium clones in an abundant reef coral

Genetic data are rapidly advancing our understanding of various biological systems including the ecology and evolution of coral-algal symbioses. The fine-scale interactions between individual genotypes of host and symbiont remain largely unstudied and constitute a major gap in knowledge. By applying microsatellite markers developed for both host and symbiont, we investigated the intra-colony diversity, prevalence and stability of Symbiodinium glynni (type D1) multilocus genotypes in association with dense populations of Pocillopora at two sites in the Gulf of California. The genetic diversity and allelic frequencies in reef populations of S. glynni remained stable over three years. Common clone genotypes persisted over this period and no temporal population subdivision (ΦPT = 0.021 & -0.003) was detected. Collections from circular plots showed no statistical correlation between related Pocillopora individuals and their associations with particular S. glynni genotypes, with no spatial structuring or clonal aggregation across a reef for the symbiont. From permanent linear transects, samples were analyzed from multiple locations within a colony and some were re-sampled ~one year later. Many of these multi-sampled colonies (~ 53%) were dominated by a single S. glynni genotype and tended to associate with the same symbiont genotype(s) over time, while colony ramets often possessed unrelated symbiont genotypes. While specificity is high between host and symbiont species, associations between genotypes of Pocillopora and S. glynni are apparently more flexible over space and time. The abundance of sexually recombinant genotypes of S. glynni represents extensive genetic variation upon which natural selection may act; this combined with greater interchangeability among host and symbiont genotypes might provide adaptive mechanisms for these symbioses to evolve rapidly to changes in environmental conditions, and allow particular symbiont genotypes to spread through a host population.

遗传数据正快速推动我们对各类生物系统的认知，其中包括珊瑚-藻类共生体的生态学与演化过程。宿主与共生体的单个基因型间的精细尺度互作仍鲜有研究，这是当前学术认知的一大空白。本研究通过开发适用于宿主与共生体的微卫星标记（microsatellite markers），针对加利福尼亚湾两处站点的密集杯形珊瑚（Pocillopora）种群，探究了Symbiodinium glynni（D1型）的菌落内多样性、流行率及稳定性，及其多基因座基因型的关联情况。Symbiodinium glynni珊瑚礁种群的遗传多样性与等位基因频率在三年间保持稳定。常见的克隆基因型在此期间持续存在，未检测到显著的种群时间分化（ΦPT = 0.021 与 -0.003）。圆形样地的采样结果显示，亲缘关系相近的杯形珊瑚个体与其携带的特定Symbiodinium glynni基因型之间无统计学相关性，共生体在珊瑚礁范围内未呈现空间结构或克隆聚集现象。通过永久性线性样带，本研究对单个菌落内多个位点的样本进行了分析，并对其中部分样本在约一年后进行了重新采样。在这些多次采样的菌落中，约53%以单一Symbiodinium glynni基因型为主，且随时间推移倾向于保持与同一共生体基因型的关联；而菌落分株通常携带非亲缘关系的共生体基因型。尽管宿主与共生体物种间的特异性较高，但杯形珊瑚与Symbiodinium glynni的基因型关联在空间与时间尺度上显然更具灵活性。Symbiodinium glynni大量的有性重组基因型蕴含着自然选择可作用的广泛遗传变异；结合宿主与共生体基因型间更强的可互换性，这或许为这类共生体快速响应环境变化演化提供了适应性机制，同时也使得特定共生体基因型能够在宿主种群中扩散。