Cronk Quentin, Ojeda Isidro
Botanical Garden and Centre for Plant Research, University of British Columbia, 6804 SW Marine Drive, Vancouver V6T 1Z4, Canada.
J Exp Bot. 2008;59(4):715-27. doi: 10.1093/jxb/ern009. Epub 2008 Mar 7.
Evolutionary shifts to bird pollination (ornithophily) have occurred independently in many lineages of flowering plants. This shift affects many floral features, particularly those responsible for the attraction of birds, deterrence of illegitimate flower visitors (particularly bees), protection from vigorous foraging by birds, and accurate placement of pollen on bird's bodies. Red coloration appears to play a major role in both bee-deterrence and bird-attraction. Other mechanisms of bird-attraction include the production of abundant dilute nectar and the provision of secondary perches (for non-hovering birds). As a result of selection for similar phenotypic traits in unrelated bird-pollinated species, a floral syndrome of ornithophily can be recognized, and this review surveys the component floral traits. The strong convergent evolution evident in bird-pollinated flowers raises a question about the nature of the genetic mechanisms underlying such transitions and whether the same gene systems are involved in most cases. As yet there is too little information to answer this question. However, some promising model systems have been developed that include closely related bee and bird-pollinated flowers, such as Ipomoea, Mimulus, and Lotus. Recent studies of floral developmental genetics have identified numerous genes important in the development of the floral phenotype, which are also potential candidates for involvement in shifts between bee-pollination and bird pollination. As more whole-genome information becomes available, progress should be rapid.
向鸟类传粉（鸟媒）的进化转变在许多开花植物谱系中独立发生。这种转变影响许多花部特征，尤其是那些负责吸引鸟类、阻止不合法的花访客（特别是蜜蜂）、保护花朵免受鸟类剧烈觅食以及将花粉准确放置在鸟类身上的特征。红色似乎在阻止蜜蜂和吸引鸟类方面都起着主要作用。其他吸引鸟类的机制包括产生大量稀释花蜜和提供次级栖息处（供非悬停鸟类使用）。由于在不相关的鸟媒传粉物种中对相似表型性状进行选择，鸟媒传粉的花部综合征得以识别，本综述对花部组成性状进行了概述。鸟媒传粉的花中明显的强烈趋同进化引发了一个问题，即这种转变背后的遗传机制的本质是什么，以及在大多数情况下是否涉及相同的基因系统。目前尚无足够信息来回答这个问题。然而，已经开发了一些有前景的模型系统，其中包括密切相关的蜜蜂传粉和鸟媒传粉的花，如甘薯属、沟酸浆属和百脉根属。最近对花发育遗传学的研究已经确定了许多对花表型发育很重要的基因，这些基因也是参与蜜蜂传粉和鸟媒传粉转变的潜在候选基因。随着更多全基因组信息的可得，进展应该会很快。
