Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada.
Ann Bot. 2012 Feb;109(3):667-79. doi: 10.1093/aob/mcr172. Epub 2011 Aug 10.
Floral variation, pollination biology and mating patterns were investigated in sunbird-pollinated Babiana (Iridaceae) species endemic to the Western Cape of South Africa. The group includes several taxa with specialized bird perches and it has been proposed that these function to promote cross-pollination.
Pollinator observations were conducted in 12 populations of five taxa (B. ringens subspp. ringens, australis, B. hirsuta, B. avicularis, B. carminea) and geographic variation in morphological traits investigated in the widespread B. ringens. Experimental pollinations were used to determine the compatibility status, facility for autonomous self-pollination and intensity of pollen limitation in six populations of four taxa. Allozyme markers were employed to investigate mating patterns in four populations of three species.
Sunbirds were the primary pollinators of the five Babiana taxa investigated. Correlated geographical variation in perch size, flower size and stigma-anther separation was evident among B. ringens populations. Experimental pollinations demonstrated that B. ringens and B. avicularis were self-compatible with variation in levels of autonomous self-pollination and weak or no pollen limitation of seed set. In contrast, B. hirsuta was self-incompatible and chronically pollen limited. Estimates of outcrossing rate indicated mixed mating with substantial self-fertilization in all species investigated.
Despite the possession of specialized bird perches in B. ringens and B. avicularis, these structures do not prevent considerable selfing from occurring, probably as a result of autonomous self-pollination. In eastern populations of B. ringens, smaller flowers and reduced herkogamy appear to be associated with a shift to predominant selfing. Relaxed selection on perch function due to increased selfing may explain the increased incidence of apical flowers in some populations.
对南非西开普省特有的蜂鸟授粉的凤仙花属（鸢尾科）物种的花部变异、传粉生物学和交配模式进行了研究。该组包括几个具有特殊鸟类栖息结构的分类群，有人提出这些结构的功能是促进异花授粉。
在五个分类群（B. ringens 亚种 ringens、australis、B. hirsuta、B. avicularis、B. carminea）的 12 个种群中进行了传粉者观察，并在分布广泛的 B. ringens 中调查了形态特征的地理变异。实验授粉用于确定六个种群的四个分类群的相容性状态、自主自交的便利性和花粉限制的强度。同工酶标记用于研究三个物种的四个种群中的交配模式。
蜂鸟是五种凤仙花属植物的主要传粉者。B. ringens 种群中存在着明显的与栖息地相关的大小、花大小和柱头-花药分离的大小的变化。实验授粉表明，B. ringens 和 B. avicularis 是自交亲和的，具有不同水平的自主自交能力，并且种子结实的花粉限制较弱或没有。相比之下，B. hirsuta 是自交不亲和的，并且长期受到花粉限制。异交率的估计表明，在所研究的所有物种中，混合交配存在大量的自交。
尽管 B. ringens 和 B. avicularis 具有特殊的鸟类栖息结构，但这些结构并不能阻止大量的自交发生，可能是由于自主自交的原因。在 B. ringens 的东部种群中，小花和减少的雌雄异熟似乎与主要自交的转变有关。由于自交增加而导致对栖息地功能的选择放松，可能解释了一些种群中顶生花的增加。
