Department of Biological Sciences and Behavioural Ecology Research Group, 8888 University Drive, Simon Fraser University, Burnaby, British Columbia V5A 1S6 Canada.
Am J Bot. 2004 Aug;91(8):1200-7. doi: 10.3732/ajb.91.8.1200.
Assumed trade-offs between male and female functions in hermaphroditic flowers have been difficult to demonstrate. Collinsia parviflora (Scrophulariaceae) is a winter annual that exhibits significant among-population variation in corolla size in British Columbia, Canada. We asked whether reduction in secondary male allocation (i.e., the attractive corolla), a preliminary indicator of mating system, was matched by a reduction in primary male allocation (i.e., pollen production), and whether there were allocation trade-offs between male and female function both within and among six study populations. Larger-flowered populations allocated more to male function (androecium and corolla biomass), and because populations did not vary in female biomass allocation (gynoecium and calyx), population differences were not due to simple allometric scaling. Populations also differed in per-flower gamete production (pollen and ovules). We found male-female trade-offs within populations between androecium and gynoecium mass and between corolla and calyx mass. Among populations, there was a marginal trade-off between pollen and ovule production and a significant within-male trade-off between pollen grain size and number. Trade-offs between the sexes were primarily apparent when we controlled for flower size in the analysis. Variation among populations in sex allocation may reflect different optima related to the mating system.
雌雄功能之间的假定权衡在雌雄同体花中很难证明。柯林斯氏风铃草（玄参科）是一种冬季一年生植物，在加拿大不列颠哥伦比亚省表现出显著的种群间花被大小变异。我们想知道次级雄性分配（即有吸引力的花被）的减少是否与初级雄性分配（即花粉产生）的减少相匹配，以及在六个研究种群内和种群间是否存在雌雄功能之间的分配权衡。花更大的种群分配更多的雄性功能（雄蕊和花被生物量），并且由于种群在雌性生物量分配（雌蕊和花萼）方面没有差异，因此种群差异不是由于简单的异速生长比例。种群也在每朵花的配子产生（花粉和胚珠）方面存在差异。我们在种群内发现了雄蕊和雌蕊质量之间以及花被和花萼质量之间的雌雄之间的权衡。在种群间，花粉和胚珠产生之间存在边际权衡，花粉粒大小和数量之间存在显著的雄性内权衡。当我们在分析中控制花的大小时，两性之间的权衡才变得明显。性别分配在种群间的差异可能反映了与交配系统有关的不同最优值。
