Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, K9J 0G2, Canada.
Department of Biology, Trent University, Peterborough, ON, K9J 0G2, Canada.
Heredity (Edinb). 2020 Mar;124(3):514-523. doi: 10.1038/s41437-019-0286-z. Epub 2019 Dec 11.
The spatial genetic structure (SGS) of plant populations is determined by the outcome of key ecological processes, including pollen and seed dispersal, the intensity of local resource competition among newly recruited plants, and patterns of mortality among established plants. Changes in the magnitude of SGS over time can provide insights into the operation of these processes. We measured SGS in a population of the clonal aquatic plant, Sagittaria latifolia that had been disturbed by flooding, both before and after the flood. Over the four-year interval between measurements, we found substantial changes in the magnitude of SGS. In the first measurement (pre-flood), SGS was weak, even over short distances. By contrast, there was substantial SGS in the second measurement (post-flood), particularly over short distances. This change in SGS was accompanied by near complete turnover in the genotypic composition of the population. The genotypic richness of the population (the number of unique clones scaled by the sample size) was halved over the four-year interval. The clonal subrange-the distances between shoots within clones-also shrank considerably, with more than 5% of shoots having clone-mates at distances >10 m before the flood, but fewer than 5% of shoots having clone-mates at distances beyond 2 m afterwards. Clonal turnover and the re-establishment of SGS in clonal populations are both expected following local extirpation and recruitment. These data reveal the genetic signatures of disturbance and a subsequent flush of seedling recruitment and clonal expansion.
植物种群的空间遗传结构（SGS）由关键生态过程的结果决定，包括花粉和种子传播、新定植植物之间的局部资源竞争强度，以及已定植植物的死亡率模式。SGS 随时间的变化可以深入了解这些过程的运作情况。我们在受洪水干扰的水生植物箭叶莎种群中测量了 SGS，分别在洪水前后进行了测量。在两次测量之间的四年时间内，我们发现 SGS 的幅度发生了很大变化。在第一次测量（洪水前），SGS 很弱，即使在短距离内也是如此。相比之下，第二次测量（洪水后）存在显著的 SGS，尤其是在短距离内。这种 SGS 的变化伴随着种群基因型组成的近乎完全更替。种群的基因型丰富度（通过样本量缩放的独特克隆数量）在四年时间内减半。克隆亚区-克隆内芽之间的距离-也大大缩小，洪水前有超过 5%的芽在 10 米以上的距离上有克隆伙伴，但洪水后有超过 5%的芽在 2 米以外的距离上有克隆伙伴。克隆更替和克隆种群中 SGS 的重新建立都预计会在局部灭绝和再定植后发生。这些数据揭示了干扰的遗传特征，以及随后的幼苗再定植和克隆扩张。
