Shao Jian-Wen, Zhang Xiao-Ping, Zhang Zhong-Xing, Zhu Guo-Ping
College of Life Science, Anhui Normal University, Wuhu 241000, China.
J Integr Plant Biol. 2008 Sep;50(9):1151-60. doi: 10.1111/j.1744-7909.2008.00655.x.
The reproductive ability related to the population size of the endangered and endemic species Primula merrilliana Schltr. was investigated. In 26 populations observed, only four contain more than 500 flowering individuals, whereas most of them (53.8%) consist of less than 100 flowering individuals. Though the ratio of pin and thrum plants keeps its balance at 1:1 for all populations, the frequency of pin and thrum flowers was significantly biased in most small populations. Population size strongly affected reproductive success; plants in small populations produced significantly fewer flowers and fruits per plant and fewer seeds per fruit, and therefore fewer seeds per plant. The floral density was another important factor that influenced the reproductive success of P. merrilliana, because four main reproductive success parameters (fruits per plant, seeds per fruit, seeds per plant, and the proportion of flowers setting fruit) were all positively correlated with floral density. The size of plants and the number of leaves per plant (measure of habitat quality) were not influenced by the variation of population size, suggesting that the reduced fecundity in small populations may not be a consequence of lower habitat quality. Inbreeding depression and pollen limitation as a result of less attractiveness in small populations are therefore likely explanations for these patterns.
对濒危特有物种安徽羽叶报春（Primula merrilliana Schltr.）与种群大小相关的繁殖能力进行了调查。在观察的26个种群中，只有4个种群拥有超过500株开花个体，而大多数种群（53.8%）的开花个体少于100株。尽管所有种群中雌雄蕊异长植株的比例保持在1:1的平衡状态，但在大多数小种群中，雌雄蕊异长花的频率存在显著偏差。种群大小强烈影响繁殖成功率；小种群中的植株单株产生的花和果实显著较少，每个果实中的种子也较少，因此单株种子数量也较少。花密度是影响安徽羽叶报春繁殖成功的另一个重要因素，因为四个主要的繁殖成功参数（单株果实数、单果种子数、单株种子数以及结实花的比例）均与花密度呈正相关。植株大小和单株叶片数量（栖息地质量的指标）不受种群大小变化的影响，这表明小种群中繁殖力下降可能不是栖息地质量较低的结果。因此，近亲繁殖衰退以及小种群中吸引力较低导致的花粉限制可能是这些模式的合理解释。
