Maternal provisioning, sibling rivalry and seed mass variability in the dioecious shrub Rhamnus alpinus
Maternal provisioning, sibling rivalry and seed mass variability in the dioecious shrub Rhamnus alpinus
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DOI：
10.1023/a:1022430302689
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发表时间：
2003-01-01
影响因子：
1.9
通讯作者：
Obeso, JR
中科院分区：
文献类型：
--
作者：
Bañuelos, MJ;Obeso, JR
在这篇文章中，我们研究了高山鼠李种子供应的变异性来源，这是一种雌雄异株的灌木，生产三种子肉质果实(范围1-4)。由于果核在果实内部是径向定向的，因此我们进行了授粉试验，用不同的供粉者在不同的雌株上进行单一授粉和混合授粉。我们发现母体对孵化大小和种子质量有很强的影响。虽然我们没有发现花粉量或花粉来源对座果率、孵化大小和种子质量的影响，但在多次授粉处理后，所有变量都表现出增强的值。此外，我们还发现，在多次授粉后，种子质量的窝内差异增加，这表明当多个供体参与授粉时，确实会发生多个兄弟姐妹，兄弟姐妹竞争可能是种子供应中的一种机制，放弃了母本选择作为替代方案。我们关于资源分配的结果符合一个层次模型，因为份额的差异在优势等级下增加，中等大小的种子对资源分配最不敏感，并且在果实质量方面，差异随着可用资源的增加而减小。因此，母体效应、供粉者数量和兄弟姐妹竞争是高山红豆杉种子质量变异的原因。
In this paper, we study the sources of variability in seed provisioning in Rhamnus alpinus, a dioecious shrub producing three-seeded fleshy fruits (range 1-4). Discarding position effects in access to resources as a source of variation, since pyrenes are radially oriented inside the fruit, we conducted a pollination experiment, in which different pollen donors were used to make single and mixed pollinations on different female plants. We found strong maternal effects on brood size and seed mass. Although we found no effects of pollen load or pollen source on fruit set, brood size or seed mass, all variables showed enhanced values after multiple pollination treatments. Furthermore, we found an increase of intra-brood variance in seed mass after multiple pollination, suggesting that multiple siring really occurs when multiple donors were involved in pollination, and that sibling rivalry could be a mechanism implicated in seed provisioning, discarding maternal choice as the alternative scenario. Our results on resource provisioning fits with a hierarchical model, since disparities in shares increased down the dominance rank, being the middle sized seed the least sensitive to resource partitioning, and the disparities were reduced when more resources were available in terms of fruit mass. Maternal effects, number of pollen donors, and sibling competition are therefore accounting for seed mass variability in R. alpinus.