Dpto Biología Organismos y Sistemas,Unidad de Ecología, Universidad de Oviedo, E33071 Oviedo, Spain; and.
Am J Bot. 1998 Nov;85(11):1602-8.
Sex ratio and sexual dimorphism in physiology and growth were studied in the dioecious tree Ilex aquifolium at two localities in northern Spain. Genet sex ratio was significantly male biased in one locality but not in the other. However, ramet and flowering ramet sex ratios were male biased at both study sites. Males had significantly thicker main trunks than females in one locality and produced more ramets in the other. Growth rate, estimated from mean width of annual rings, did not differ between localities, but males produced wider rings than females at both sites. Mean annual growth rates over the last 10, 20, and 30 yr were significantly higher for males. Measurements of chlorophyll fluorescence indicated that the efficiency of photosynthesis of leaves on nonfruiting branches of females was higher than for leaves on branches of male plants under low-light conditions, though not under saturating-light conditions. Efficiency of photosynthesis was significantly lower on fruiting branches of female plants than on nonfruiting branches. We discuss whether the observed between-sex differences are attributable to the higher cost of reproduction in females and/or to pollen competition.
在西班牙北部的两个地点，研究了雌雄异株的冬青树 Ilex aquifolium 的性别比例和生理性别二态性以及生长情况。在一个地点，遗传性别比例明显偏向雄性，但在另一个地点则没有。然而，在两个研究地点，无性系和开花无性系的性别比例都偏向雄性。在一个地点，雄性的主树干比雌性的树干明显粗，而在另一个地点，雄性产生的无性系比雌性多。从年平均宽度估计的生长速度在两个地点都没有差异，但在两个地点，雄性的年轮都比雌性宽。过去 10、20 和 30 年的平均年增长率男性明显更高。叶绿素荧光测量表明，在低光照条件下，雌性非结果枝上叶片的光合作用效率高于雄性植物的枝条上叶片的光合作用效率，但在饱和光照条件下则不然。雌性植物结果枝上叶片的光合作用效率明显低于非结果枝上叶片的光合作用效率。我们讨论了观察到的性别间差异是否归因于雌性较高的繁殖成本和/或花粉竞争。
