A spatially explicit model for flowering time in bamboos: long rhizomes drive the evolution of delayed flowering
A spatially explicit model for flowering time in bamboos: long rhizomes drive the evolution of delayed flowering
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竹子开花时间的空间显式模型：长根茎驱动延迟开花的进化
DOI：
10.1111/1365-2745.12390
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发表时间：
2015
影响因子：
5.5
通讯作者：
Yoshihisa Suyama and Akiko Satake
中科院分区：
文献类型：
--
作者：
Yuuya Tachiki;Akifumi Makita;Yoshihisa Suyama and Akiko Satake
无性系植物产生半自主模块（分株）。品种的空间分布通过自花授粉、亲缘竞争和基因型间对空间和养分的竞争来影响其一生的繁殖成功。这些反过来又影响了单心植物（开花是致命的）开花时间的进化，比如竹子。竹子的营养生长期（开花间隔）表现出从热带（短间隔）到温带（长间隔）的地理差异。然而，这种地理趋势在开花间隔期出现的机制仍然难以捉摸。我们假设开花间隔的差异是由影响分株空间排列和亲缘竞争程度的生态特征决定的。利用空间显式数学模型，研究了根茎伸长、种子和花粉传播范围以及近交抑制对开花间隔演化的影响。开花间隔期随着根茎长度的增加而延长，但随着种子传播范围的扩大而缩短。然而，当这些范围非常大时，花期受影响较小。这些结果可能是由于基因的空间结构导致的基因内竞争所致。如果根茎较短，则每个基因通过营养生长形成块状结构，并受到高内竞争的影响。提早开花可能会减少这种竞争。当种子传播范围较短时，种子间的亲缘竞争加剧，延迟开花是较好的策略。当这些参数非常大时，这种竞争的影响减小，开花间隔不变。近交抑制的效果取决于营养生长形成的分株的空间分布。近交抑制降低了繁殖成功率，因此，当根茎长度和花粉传播范围都较短时，选择延迟开花，与邻近兄弟姐妹近交是不可避免的。无性系植物开花间隔的进化结果受基因空间分布的影响。竹子开花间隔的地理格局可以用根茎长度的差异来解释。不同根茎长度的种间比较应通过收集分株空间排列的长期人口统计学数据进行检验。
Clonal plants produce semi‐autonomous modules (ramets). The spatial distribution of ramets affects lifetime reproductive success via self‐pollination, kin competition and competition among genotypes over space and nutrients. These, in turn, influence the evolution of the timing of flowering in monocarps (flowering is fatal), such as bamboos.The vegetative growth period (flowering interval) in bamboos shows a geographic cline from tropical (short‐interval) to temperate (long‐interval) regions. However, the mechanisms underlying the emergence of this geographic trend in flowering interval remain elusive.We hypothesized that differences in flowering interval are determined by ecological features that affect the spatial arrangement of ramets and the degree of kin competition. Using a spatially explicit mathematical model, we examined the effects of rhizome elongation, seed and pollen dispersal ranges and inbreeding depression on the evolution of flowering interval.Flowering interval became longer as rhizome length increased but was shorter as seed dispersal range increased. However, flowering interval was less affected when these ranges were extremely large. These results could be caused by intragenet competition due to the spatial structure of genets. If the rhizome is short, each genet forms a clumping structure by vegetative growth and is subject to high intragenet competition. Early flowering may reduce this competition. When seed dispersal range is shorter, kin competition among seeds becomes greater and delayed flowering is a better strategy. When these parameters are extremely large, the effects of this type of competition are reduced, and flowering interval does not change.The effect of inbreeding depression depends on the spatial distribution of ramets formed by vegetative growth. Inbreeding depression reduces reproductive success, and hence, delayed flowering is selected for when both rhizome length and pollen dispersal range are short, and inbreeding with neighbouring siblings is unavoidable.Synthesis. The evolutionary consequences of flowering interval in clonal plants are affected by the spatial distribution of genets. Geographic patterns in flowering interval of bamboos can be explained by differences in rhizome length. Interspecific comparisons among species with different rhizome lengths should be examined by collecting long‐term demographic data on the spatial arrangement of ramets.