Baker Kathleen, Richards A J, Tremayne Michelle
Department of Agricultural and Environmental Science, Ridley Building, University of Newcastle upon Tyne NE1 7RU, UK.
New Phytol. 1994 Nov;128(3):563-570. doi: 10.1111/j.1469-8137.1994.tb03002.x.
Using two dimorphic species with diallelic incompatibility, Primula farinosa L. and Armeria maritima (Miller) Willd., we tested the hypothesis that an association of seedling performance with seed size, and an inverse association of seed size with seed number, might, contrary to most fitness models, select for plants which set relatively few seeds. In P. farinosa we discovered positive relationships between seed number per capsule and capsule number per inflorescence. As capsules are formed in most flowers, scapes with few flowers set the fewest seeds per capsule. This suggests that conspicuousness to pollinators and/or plant resource play an important role in reproductive success in this species. Seed size and seedling performance were also positively associated. For P. farinosa, which has multi-seeded fruits, we discovered an inverse association between seed size and seed number for capsules containing more than 65 seeds. We suggest that stabilizing selection may occur for flower number per inflorescence in this species, as inflorescences with 8-11 capsules tend to set many seeds which may be inefficiently small. This tends to confirm our hypothesis. However, for A. maritima there is a positive association between seed size and seed number per inflorescence. For such plants with single-seeded fruits there should be directional selection for large flower number pet-inflorescence, a trend which may have led to the evolution of the capitulum.
我们使用具有双等位基因不亲和性的两种二态物种——粉报春（Primula farinosa L.）和海石竹（Armeria maritima (Miller) Willd.），来检验以下假设：与大多数适合度模型相反，幼苗表现与种子大小之间的关联以及种子大小与种子数量之间的负相关，可能会选择产生相对较少种子的植株。在粉报春中，我们发现每个蒴果的种子数量与每个花序的蒴果数量之间存在正相关关系。由于大多数花朵都会形成蒴果，花朵较少的花茎每个蒴果产生的种子最少。这表明对传粉者的显眼程度和/或植物资源在该物种的繁殖成功中起着重要作用。种子大小和幼苗表现也呈正相关。对于具有多粒种子果实的粉报春，我们发现对于含有超过65粒种子的蒴果，种子大小与种子数量之间存在负相关。我们认为该物种可能对每个花序的花朵数量进行稳定选择，因为具有8 - 11个蒴果的花序往往会产生许多可能小得低效的种子。这倾向于证实我们的假设。然而，对于海石竹，种子大小与每个花序的种子数量之间存在正相关。对于这种具有单粒种子果实的植物，应该对每个花序上较大的花朵数量进行定向选择，这种趋势可能导致了头状花序的进化。
