EVOLUTION AND COEXISTENCE OF POLLINATION ECOTYPES IN AN AFRICAN GLADIOLUS (IRIDACEAE)
EVOLUTION AND COEXISTENCE OF POLLINATION ECOTYPES IN AN AFRICAN GLADIOLUS (IRIDACEAE)
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DOI：
10.1111/j.1558-5646.2009.00880.x
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发表时间：
2010-04-01
期刊：
影响因子：
3.3
通讯作者：
Johnson, Steven D.
中科院分区：
文献类型：
--
作者：
Anderson, Bruce;Alexandersson, Ronny;Johnson, Steven D.
传粉者介导的选择被认为是植物物种形成的关键驱动因素。我们研究了天蛾传粉者在驱动非洲蝴蝶花的异地分化和维持形态类型的共域共存方面的潜在作用。本种的花管长度在其地理范围内从35毫米到130毫米不等，并反映了当地鹰蛾群落的普遍舌长。花管长度的分布是双峰分布，有两个相对离散的类别--长(约90毫米)或短(约50毫米)--与南非东部鹰蛾舌长的双峰分布相匹配。在这两个花形态之间的接触点，我们发现几乎没有中等长度的个体，这表明尽管它们之间存在干扰，但它们之间的基因流动有限。开花物候的差异似乎是该地点不同形态之间的主要隔离障碍。长管型和短管型在花香的化学成分上有明显的差异，这一特征可以作为鹰蛾特定形态觅食的线索。对管长的正向选择在两个变型中都发生了。
Pollinator-mediated selection has been suggested as a key driver of speciation in plants. We examined the potential role of hawkmoth pollinators in driving allopatric divergence and maintaining sympatric coexistence of morphotypes in the African iris Gladiolus longicollis. Floral tube length in this species varies from 35 mm to 130 mm across its geographic range and reflects the prevailing tongue lengths of local hawkmoth assemblages. The distribution of floral tube lengths is bimodal with two relatively discrete categories-long (about 90 mm) or short (about 50 mm)-that match the bimodal distribution of hawkmoth tongue lengths in eastern South Africa. At a contact site between these two floral morphs, we found few individuals of intermediate length, suggesting limited gene flow between morphs despite their interfertility. A difference in flowering phenology appears to be the main isolating barrier between morphs at this site. Long-and short-tubed morphs differed markedly in the chemical composition of their floral fragrance, a trait that could be used as a cue for morph-specific foraging by hawkmoths. Positive directional selection on tube length was found to occur in both morphs.