Game theory provides no explanation for seed size variation in grasslands
Game theory provides no explanation for seed size variation in grasslands
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DOI：
10.1007/s00442-005-0001-z
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发表时间：
2005-06-01
期刊：
影响因子：
2.7
通讯作者：
Eriksson, O
中科院分区：
文献类型：
--
作者：
Eriksson, O
博弈论模型已被提出来解释在大多数类型的植被中，种子大小在物种间的显着差异。根据这些模型，这是基于种子大小和种子数量之间存在的权衡;种子较小的物种可以入侵任何物种的混合物，由于其数量优势，和种子较大的物种可以入侵任何物种的混合物，由于其竞争优势，在招聘过程中种子较小的物种。然而，到目前为止，有非常有限的证据，种子大小的影响，不同物种之间的招聘相互作用。一项实验设计使用16种在瑞典草原，不同的384倍的种子大小。物种成对播种，单独在干扰与未受干扰的小地块放牧与未放牧的草地，并记录由此产生的招聘。试验地的苗木密度均在自然范围内。干扰和放牧对补充都有积极的影响。种子大小不影响招聘，除了从一个趋势，增加种子大小的招聘不太依赖于干扰。招聘种子较小的物种不受种子较大的物种的存在。种子较大的物种通常不会在直接竞争中获胜。这些结果表明，游戏理论模型不能解释这些草原上的物种之间的种子大小变化的维护。种子大小变异的其他解释是，小规模的异质性提供了有利于一系列不同种子大小的条件，或者种子大小以外的其他属性有效地决定了补充。
Game theoretical models have been suggested to explain the maintenance of a remarkable variation in seed size across species in most types of vegetation. According to these models, which are based on the existence of a trade-off between seed size and seed number; smaller-seeded species can invade any species mixture due to their numerical advantage, and larger-seeded species can invade any species mixture due to their competitive superiority over smaller-seeded species during recruitment. However, till now, there is very limited evidence for seed size effects on recruitment interactions among different species. An experiment was designed using 16 species in Swedish grasslands, varying 384-fold in seed size. Species were sown pairwise and alone in disturbed versus undisturbed small plots in grazed versus ungrazed grassland, and the resulting recruitment was recorded. Seedling densities in the experimental plots were within the natural range. Both disturbance and grazing had a positive effect on recruitment. Seed size did not affect recruitment except from a tendency that increasing seed size made recruitment less dependent on disturbance. Recruitment of smaller-seeded species was not affected by the presence of larger-seeded species. Larger-seeded species did not generally win in direct contest. These results suggest that game theoretical models do not explain maintenance of seed size variation across species in these grasslands. Alternative explanations for seed size variation are that either small-scale heterogeneity provide conditions favouring a range of different seed sizes or other attributes than seed size effectively determine recruitment.