Institute of Science and Technology, Klosterneuberg 3400, Austria.
Mol Ecol. 2012 Aug;21(15):3640-3. doi: 10.1111/j.1365-294X.2012.05643.x.
Since Darwin's pioneering research on plant reproductive biology (e.g. Darwin 1877), understanding the mechanisms maintaining the diverse sexual strategies of plants has remained an important challenge for evolutionary biologists. In some species, populations are sexually polymorphic and contain two or more mating morphs (sex phenotypes). Differences in morphology or phenology among the morphs influence patterns of non-random mating. In these populations, negative frequency-dependent selection arising from disassortative (intermorph) mating is usually required for the evolutionary maintenance of sexual polymorphism, but few studies have demonstrated the required patterns of non-random mating. In the current issue of Molecular Ecology, Shang et al. (2012) make an important contribution to our understanding of how disassortative mating influences sex phenotype ratios in Acer pictum subsp. mono (painted maple), a heterodichogamous, deciduous tree of eastern China. They monitored sex expression in 97 adults and used paternity analysis of open-pollinated seed to examine disassortative mating among three sex phenotypes. Using a deterministic 'pollen transfer' model, Shang et al. present convincing evidence that differences in the degree of disassortative mating in progeny arrays of the sex phenotypes can explain their uneven frequencies in the adult population. This study provides a useful example of how the deployment of genetic markers, demographic monitoring and modelling can be integrated to investigate the maintenance of sexual diversity in plants.
自达尔文对植物生殖生物学的开创性研究（例如达尔文 1877）以来，理解维持植物多样化有性策略的机制一直是进化生物学家的重要挑战。在一些物种中，种群是有性多态的，包含两种或更多种交配形态（性别表型）。形态之间在形态或物候上的差异影响非随机交配的模式。在这些种群中，来自于不相容（种间）交配的负频率依赖选择通常是维持性多态性进化所必需的，但很少有研究证明了所需的非随机交配模式。在本期《分子生态学》中，Shang 等人（2012）对我们理解不相容交配如何影响中国东部异交、落叶乔木 Acer pictum subsp. mono（彩叶枫）的性表型比例做出了重要贡献。他们监测了 97 个成年个体的性别表达，并利用开放授粉种子的亲子分析来检验三种性别表型之间的不相容交配。Shang 等人使用确定性的“花粉转移”模型，提供了令人信服的证据，表明在性表型后代群体中不相容交配程度的差异可以解释它们在成年群体中的不均匀频率。这项研究提供了一个有用的例子，说明如何部署遗传标记、人口监测和建模来研究植物中性多样性的维持。
