Stanton Maureen L, Snow Allison A, Handel Steven N, Bereczky Judith
Department of Botany, University of California, Davis, CA, 95616.
Department of Biological Sciences, Rutgers University, Piscataway, NJ, 08855.
Evolution. 1989 Mar;43(2):335-346. doi: 10.1111/j.1558-5646.1989.tb04231.x.
We conducted field experiments to determine how a naturally occurring petal-color polymorphism influences mating patterns in wild radish (Raphanus raphanistrum). The polymorphism is controlled at a single genetic locus, with white petal color being completely dominant to yellow. In experimental populations with equal numbers of yellow- and white-flowered homozygous individuals, insect visitors strongly discriminated against white flowers. Pieris rapae, the most frequent pollinator, was almost 50% more likely to visit yellow than white flowers. Maternal fecundity did not differ between the morphs and was not significantly influenced by a plant's compatibility with potential donors, suggesting that seed production was not limited by receipt of compatible pollen. In contrast, the yellow-flowered morph sired approximately 75% of all seeds produced during the study. This paternity proportion was consistently greater than that expected on the basis of postpollination compatibility measures and was indistinguishable from that expected on the basis of pollinator-visitation frequency. We conclude that the male-fitness advantage of the yellow morph resulted from enhanced pollen export due to the greater attractiveness of its flowers to insect pollinators. With color morphs evenly distributed in experimental arrays, insects did not move assortatively on the basis of petal color, and we found no evidence for assortative pollen flow due to the floral polymorphism. Once postpollination compatibility relationships within populations were taken into account, paternal success of yellow donors did not differ between yellow- and white-flowered maternal plants.
我们进行了田间实验，以确定自然发生的花瓣颜色多态性如何影响野生萝卜（Raphanus raphanistrum）的交配模式。这种多态性由单个基因座控制，白色花瓣颜色对黄色完全显性。在具有等量黄色和白色花纯合个体的实验种群中，昆虫访客强烈歧视白色花朵。最常见的传粉者菜粉蝶访问黄色花朵的可能性比白色花朵高出近50%。两种形态的母本繁殖力没有差异，并且不受植物与潜在花粉供体兼容性的显著影响，这表明种子生产不受兼容花粉接收的限制。相比之下，黄色花形态产生了研究期间所有种子的约75%。这个父本比例始终大于基于授粉后兼容性测量预期的比例，并且与基于传粉者访问频率预期的比例没有区别。我们得出结论，黄色形态的雄性适合度优势源于其花朵对昆虫传粉者更具吸引力，从而增强了花粉输出。由于颜色形态在实验阵列中均匀分布，昆虫不会根据花瓣颜色进行选择性移动，并且我们没有发现由于花多态性导致的选择性花粉流动的证据。一旦考虑到种群内授粉后的兼容性关系，黄色花粉供体在黄色和白色花母本植物中的父本成功率没有差异。
