Pollinator-mediated selection on flower-tube length in a hawkmoth-pollinated Gladiolus (Iridaceae)
Pollinator-mediated selection on flower-tube length in a hawkmoth-pollinated Gladiolus (Iridaceae)
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DOI：
10.1098/rspb.2001.1928
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发表时间：
2002-03-22
影响因子：
4.7
通讯作者：
Johnson, SD
中科院分区：
文献类型：
--
作者：
Alexandersson, R;Johnson, SD
达尔文的机械模型，即选择有利于植物的花管超过舌头长度的主要传粉者，进行了测试，使用未经处理的植物的鹰蛾授粉的南非虹膜，唐菖蒲longicollis。研究人群的特点是异常大的表型变异的花管长度（范围56-129毫米）。试管长度与结实率和结实率呈显著正相关，表明试管长度的定向选择作用。选择归因于管长度对花粉接收的影响，作为补充手授粉显示在人口中的果实和种子集花粉有限。管长度的间接选择也可能发生通过这个性状与花序高度的相关性，虽然直接选择后者的性状是显着的，只为结实。研究地点的主要传粉者是大型天蛾Agrius convolvuli的个体，其舌头长度为85-135 mm。longicollis花和G.长颈花的筒部短于A.旋花显然不能有效地授粉，因为柱头不能有效地接触蛾的头部。这项研究表明，选择可能发生在植物之间的自然表型变异的花管长度，并支持达尔文的模型传粉媒介的选择。
Darwin's mechanistic model whereby selection favours plants with flower tubes that exceed the tongue length of the primary pollinator, was tested using unmanipulated plants of the hawkmoth-pollinated South African iris, Gladiolus longicollis. The study population was characterized by exceptionally large phenotypic variation in flower-tube length (range 56-129 mm). Directional selection on tube length was revealed by a significant positive relationship between this trait and both fruit and seed set. Selection was attributed to the effect of tube length on pollen receipt, as supplemental hand pollinations showed fruit and seed set in the population to be pollen limited. Indirect selection on tube length may also occur through the correlation of this trait with inflorescence height, although direct selection on the latter trait was significant only for seed set. The main pollinators at the study site were individuals of the large hawkmoth Agrius convolvuli that had tongue lengths of 85-135 mm. Other hawkmoths had tongues that were much too short to reach the nectar in G. longicollis flowers and seldom carried pollen of G. longicollis. Flowers with tubes shorter than the tongues of A. convolvuli are apparently not effectively pollinated because stigmas do not contact the moth's head effectively. This study demonstrates that selection may occur among plants with natural phenotypic variation in flower-tube length, and supports Darwin's model of pollinator-mediated selection.