Velichka Jenni, Friedman Jannice
Department of Biology, Queen's University, Kingston, Ontario K7L3N6, Canada.
Ann Bot. 2025 Sep 2;136(1):67-75. doi: 10.1093/aob/mcae218.
Seed dispersal impacts plant fitness by shaping the habitat and distribution of offspring, influencing population dynamics and spatial genetic diversity. Whether the evolution of dispersal strategies varies across herbaceous life forms (annual, perennial or clonal) is unresolved. In this study, we examine how seed-dispersal strategies vary between annual and perennial populations of Mimulus guttatus (syn. Erythranthe guttata), investigating differences in seedpod orientation and shape and in the probability and distance of seed dispersal.
We conducted a greenhouse experiment using 190 plants from six populations of annual and perennial M. guttatus, to compare floral orientation, seedpod architecture and its effect on seed dispersal. We used controlled wind trials to measure the probability of seed dispersal and the dispersal distance of individual seeds from plants.
We identify the following three key differences in seedpod architecture and seed dispersal in annuals and perennials: seedpods are angled more upward-facing in perennials compared with annuals; a lower proportion of seed is dispersed in perennials; and seeds disperse further in perennials than in annuals. These results are consistent with our predictions that a clonal, perennial life form should be associated with traits that increase the retention of seeds, requiring greater wind speeds to dislodge seed and increasing dispersal distance.
Despite the close genetic relationship between annual and perennial populations of M. guttatus, we find differences in seedpod architecture and seed dispersal. We suggest that perennial plants, characterized by clonal reproduction and multi-year survival, benefit from strategies that facilitate long-distance seed dispersal to mitigate competition and promote colonization of new habitats.
种子传播通过塑造后代的栖息地和分布来影响植物适合度，进而影响种群动态和空间遗传多样性。传播策略的进化在草本植物的不同生活型（一年生、多年生或克隆型）之间是否存在差异仍未得到解决。在本研究中，我们研究了一年生和多年生黄花沟酸浆（Mimulus guttatus，同物异名Erythranthe guttata）种群之间种子传播策略的差异，调查了种荚方向和形状以及种子传播的概率和距离的差异。
我们使用来自一年生和多年生黄花沟酸浆六个种群的190株植物进行了温室实验，以比较花的方向、种荚结构及其对种子传播的影响。我们通过控制风的试验来测量种子传播的概率和单个种子从植株上的传播距离。
我们确定了一年生和多年生植物在种荚结构和种子传播方面的以下三个关键差异：与一年生植物相比，多年生植物的种荚向上倾斜的角度更大；多年生植物中传播的种子比例较低；多年生植物中的种子比一年生植物中的种子传播得更远。这些结果与我们的预测一致，即克隆性的多年生生活型应该与增加种子保留的性状相关联，这需要更大的风速来驱散种子并增加传播距离。
尽管一年生和多年生黄花沟酸浆种群之间存在密切的遗传关系，但我们发现它们在种荚结构和种子传播方面存在差异。我们认为，以克隆繁殖和多年生存为特征的多年生植物受益于促进远距离种子传播的策略，以减轻竞争并促进新栖息地的定殖。
