Ashman Tia-Lynn
Botany Department, University of California, Davis, California, 95616, USA.
Evolution. 1992 Dec;46(6):1862-1874. doi: 10.1111/j.1558-5646.1992.tb01174.x.
Gynodioecious plant populations contain both hermaphrodite and female individuals. For females to be maintained they must compensate for their loss of reproductive fitness through pollen. Females may achieve compensation by producing more and/or higher quality seeds than hermaphrodites. In this study, I investigated the independent and interactive effects of maternal sexual identity and inbreeding level on fitness of the progeny of hermaphrodites and females of Sidalcea oregana ssp.spicata. Seeds produced by selling hermaphrodites and by outcrossing or sib-crossing hermaphrodites and females, were planted in the field and greenhouse. Maternal-sex effects were substantial at the juvenile stages of the life cycle; seeds of females germinated in higher proportions and produced seedlings that grew significantly faster. Inbreeding effects were manifested primarily at the adult stage of the life cycle. Outcrossed plants were significantly larger and produced more flowers per plant than sib-crossed and selfed plants growing in the greenhouse. Progeny of hermaphrodites and females appeared to respond similarly to sib-matings. The maternal-sex effects observed in Sidalcea may have been related to cytoplasmically inherited factors and could be a driving force in the maintenance of females. Inbreeding depression could play a role in determining the fitness of both sex morphs, if females experience biparental inbreeding in the field. Frequent inbreeding of hermaphrodites may not be necessary to explain the maintenance of gynodioecy in this species.
雌雄异株的植物种群中同时包含雌雄同体和雌性个体。为了使雌性个体得以维持，它们必须通过花粉来弥补自身繁殖适合度的损失。雌性个体可以通过产生比雌雄同体更多和/或质量更高的种子来实现补偿。在本研究中，我调查了母体性别身份和近亲繁殖水平对俄勒冈侧金盏花亚种穗状侧金盏花雌雄同体和雌性后代适合度的独立影响和交互影响。通过出售雌雄同体植株以及让雌雄同体和雌性植株进行异交或同胞交配所产生的种子，被种植在田间和温室中。母体性别效应在生命周期的幼年阶段较为显著；雌性植株的种子发芽比例更高，且所产生的幼苗生长速度明显更快。近亲繁殖效应主要在生命周期的成年阶段显现。在温室中，异交植株比同胞交配和自交植株显著更大，且单株产生的花朵更多。雌雄同体和雌性的后代对同胞交配的反应似乎相似。在穗状侧金盏花中观察到的母体性别效应可能与细胞质遗传因素有关，并且可能是维持雌性个体的一个驱动力。如果雌性个体在田间经历双亲近亲繁殖，近亲繁殖衰退可能在决定两种性别形态的适合度方面发挥作用。雌雄同体植株频繁的近亲繁殖可能并非解释该物种中雌雄异株维持现象的必要条件。
