Department of Biological Sciences, CW405 Biological Sciences Bldg., University of Alberta, Edmonton, AB, Canada.
Am J Bot. 2012 Jul;99(7):1243-8. doi: 10.3732/ajb.1200107. Epub 2012 Jul 4.
The development of biased sex ratios in dioecious plant species has been ascribed to either (1) factors influencing differential adult mortality of male and female plants or (2) factors acting at an early life stage that determine seed sex ratio or seedling survival.
To discriminate between these two competing hypotheses, we surveyed sex and age of 379 individuals from five species of the genus Salix across 11 alpine valleys in the southwest Yukon.
We observed uniformly female-biased sex ratios of approximately 2:1 across all adult age cohorts and patch sizes of the five willow species. No spatial variation in sex ratio occurred that could be associated with site-specific characteristics such as elevation or aspect.
Our results indicate that the female-biased sex ratios in the alpine willow species investigated in this study are not a consequence of ecological processes acting on established adult plants. The sex ratio is instead determined at an early life stage by a mechanism that remains unknown.
雌雄异株植物中偏性性别比例的发展归因于（1）影响雄性和雌性植物成年后死亡率差异的因素，或（2）作用于早期生命阶段、决定种子性别比例或幼苗存活率的因素。
为了区分这两种相互竞争的假说，我们对西南育空地区 11 个高山山谷的 5 种柳属植物的 379 个个体的性别和年龄进行了调查。
我们观察到，在所有成年年龄组和 5 种柳树的斑块大小中，性别比例大致为 2:1，偏向雌性。性别比例没有出现与特定地点特征（如海拔或朝向）相关的空间变化。
我们的研究结果表明，本研究中高山柳属植物的雌性偏性性别比例不是作用于已建立的成年植物的生态过程的结果。性别比例是由一个未知的机制在生命早期阶段决定的。
