Different cost of reproduction for the males and females of the rare dioecious shrub Corema conradii (Empetraceae).
Different cost of reproduction for the males and females of the rare dioecious shrub Corema conradii (Empetraceae).
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DOI：
10.2307/2657066
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发表时间：
2001-04
影响因子：
3
通讯作者：
Anne-Françoise Rocheleau;Gilles Houle
中科院分区：
文献类型：
--
作者：
Anne-Françoise Rocheleau;Gilles Houle
雌雄异株植物物种的雄性和雌性在生殖投资方面往往不同。这种差异经常导致不同的人口成本，表现为较低的生长、存活和/或生殖频率，和/或随着时间的推移，女性的生殖努力具有更大的可变性。我们介绍了对北美东北部沿海沙丘灌丛中的一种罕见的雌雄异株灌木Corema conRadii的研究结果。我们估计了男性和女性的生殖投资，确定了他们的年龄结构，并比较了他们在魁北克省马德莱纳岛种群中的空间格局。我们还确定了已知出现在这些岛屿上的四个种群的性别比例。开花期雄性在生殖上投入较多，但在果实生产方面，雌性在生物量、镁和钙方面的生殖投入较高，而在N、P和K方面则不是很高。种群分散的模式是有传染性的，有许多年龄相仿的个体。雄性和雌性之间没有空间隔离，尽管性别比例在空间上有所不同。雌性并不比雄性更晚开始繁殖，而且寿命似乎也并不比雄性短。但雌株的冠径向生长率均低于雄株。当用树冠截距法估计时，四个种群的性别比都是男性偏向的。然而，由于雄性的树冠生长率更高，因此性别比实际上是平衡的。较高的繁殖投资与较低的增长率相关，这代表着该物种根据性别的不同而产生不同的繁殖成本。
Males and females of dioecious plant species often differ in their reproductive investment. Such differences frequently result in differential demographic costs represented by lower growth, survival, and/or frequency of reproduction, and/or by more variable reproductive effort through time for females. We present the results of a study on Corema conradii, a rare dioecious shrub of the coastal dune heathlands of northeastern North America. We estimated the reproductive investment of both males and females, determined their age structure, and compared their spatial patterns in a population at Îles-de-la-Madeleine, Quebec. We also determined the sex ratio of the four populations known to occur on the islands. Males invested more in reproduction at flowering, but when fruit production was considered, female reproductive investment was higher in terms of biomass, Mg, and Ca, but not in terms of N, P, and K. The age frequency distribution of males and females did not differ significantly from one another. The population dispersion pattern was contagious, with patches of similar-age individuals. There was no spatial segregation between males and females, although the sex ratio varied somewhat spatially. Females did not start reproducing at a later age than males and did not appear to have a shorter longevity. However, the crown and radial growth rates of females were lower than those of males. When estimated by the crown intercept method, the sex ratio of all four populations was male biased. However, because males had a higher crown growth rate, genet sex ratio was in fact balanced. Higher investment in reproduction was associated with a lower growth rate, which represents a differential cost of reproduction according to sex in this species.