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 individ...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.展开更多
基金National Natural Science Foundation of China General Projects (30500300)the Natural Science Foundation of Anhui Province (050430501)+1 种基金the Doctoral Subject Foundation of High College of Chinese Education Commission (20060370001) the Foundation for Junior Teacher of Anhui Education Department (2005jq1051)
文摘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.
