Cruzan Mitchell B
Department of Ecology and Evolution, State University of New York at Stony Brook, Stony Brook, New York, 11794, USA.
The Rocky Mountain Biological Lab, Crested Butte, CO, 81224, USA.
Evolution. 1990 Jul;44(4):843-856. doi: 10.1111/j.1558-5646.1990.tb03809.x.
The mean volume of pollen grains and total pollen production varied both within and among plants of Erythronium grandiflorum. The second flowers of two-flowered plants tended to produce smaller and fewer grains than first flowers, but there was no overall relationship between mean pollen grain size and production per flower. I evaluated the effects of pollen size differences within and among plants on two components of male reproductive success: pollen tube growth and postfertilization siring ability. Pollen tubes grown in media were longer for second flowers, but were not correlated with the mean size of pollen grains, suggesting that (1) internal resource content of pollen (i.e., carbohydrates plus lipids) was not associated with the hydrated size of pollen, and that (2) pollen from second flowers contained more resources. I analyzed the growth rate and the fertilization ability of pollen growing in styles. Growth rate differed among donors and recipients, but no effects of pollen or donor characters (i.e., pollen production, grain size, and flower position) were detected. In single donor pollinations, pollen size was negatively correlated with fertilization ability across donors, and positively correlated with postfertilization siring ability of donors. A second experiment used pairs of donors; within-plant differences in pollen size and flower position had effects similar to the single donor experiment on fertilization ability, but among-plant differences were not significant. The results corroborate earlier experiments that suggest that the growth of pollen tubes in the style is probably controlled by the recipient, since donor characters had minimal effects on pollen fertilization ability. Postfertilization siring ability was not affected by within-plant differences in mean grain size and production. For among-donor differences, the number of seeds set for each donor was positively correlated with the mean grain volume, and when a donor producing large pollen fertilized ovules in an ovary, there was increased seed abortion for seeds in the same ovary sired by a second donor. In addition, the total number of seeds produced by a fruit was decreased when both donors had large pollen, apparently due to increased postfertilization abortion. Postfertilization processes appear to be influenced by paternal differences that are expressed through competition among developing seeds for maternal resources.
大花猪牙花植株内部以及不同植株之间，花粉粒的平均体积和花粉总产量都有所不同。双花植株的第二朵花产生的花粉粒往往比第一朵花更小、数量更少，但花粉粒平均大小与单花产量之间并无总体关联。我评估了植株内部和不同植株之间花粉大小差异对雄性繁殖成功的两个组成部分的影响：花粉管生长和受精后父本遗传能力。在培养基中生长的花粉管，第二朵花的更长，但与花粉粒的平均大小无关，这表明：（1）花粉的内部资源含量（即碳水化合物加脂质）与花粉的水合大小无关；（2）第二朵花的花粉含有更多资源。我分析了在花柱中生长的花粉的生长速率和受精能力。供体和受体之间生长速率存在差异，但未检测到花粉或供体特征（即花粉产量、粒大小和花的位置）的影响。在单供体授粉中，花粉大小与不同供体的受精能力呈负相关，与供体的受精后父本遗传能力呈正相关。第二个实验使用了成对的供体；植株内部花粉大小和花位置的差异对受精能力的影响与单供体实验类似，但不同植株之间的差异不显著。这些结果证实了早期实验，表明花柱中花粉管的生长可能受受体控制，因为供体特征对花粉受精能力影响极小。受精后父本遗传能力不受植株内部平均粒大小和产量差异的影响。对于不同供体之间的差异，每个供体的结实种子数与平均粒体积呈正相关，当产生大花粉的供体使子房中的胚珠受精时，同一子房中由第二个供体授粉产生的种子的败育率增加。此外，当两个供体花粉都大时，果实产生的种子总数减少，显然是由于受精后败育增加。受精后过程似乎受到父本差异的影响，这种差异通过发育中的种子争夺母本资源的竞争表现出来。
