Burd Martin
School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia.
Am Nat. 2008 Mar;171(3):400-4. doi: 10.1086/527499.
The Haig-Westoby model predicted that seed set in flowering plants would be equally limited by both pollen capture and resource supply because the optimal level of pollinator attraction should garner just the number of ovule fertilizations needed to consume the available seed-provisioning resources. Variability in the underlying resource and fertilization functions can disrupt this predicted optimum, a point made but only briefly explored by Haig and Westoby. Here I incorporate stochastic variation in both ovule fertilization and resource availability into the Haig-Westoby model and show that the modified model makes two noteworthy predictions: (1) pollen limitation of seed set (as measured by the response to supplemental pollen) should be common, and (2) the degree of pollen limitation may be greater when plants are more attractive to pollinators. The first prediction accords with recent meta-analyses of pollen limitation; the second remains to be examined.
海格 - 韦斯托比模型预测，开花植物的结实率将同样受到花粉捕获量和资源供应的限制，因为传粉者吸引的最佳水平应恰好获得消耗可用种子供应资源所需的胚珠受精数量。潜在资源和受精功能的变异性会扰乱这一预测的最优状态，这一点海格和韦斯托比虽已指出，但只是进行了简要探讨。在此，我将胚珠受精和资源可用性的随机变化纳入海格 - 韦斯托比模型，并表明修改后的模型做出了两个值得注意的预测：（1）结实率的花粉限制（通过对补充花粉的反应来衡量）应该很常见，（2）当植物对传粉者更具吸引力时，花粉限制的程度可能更大。第一个预测与最近关于花粉限制的荟萃分析一致；第二个预测仍有待检验。
