When push comes to shove
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Africa, now report on a population of flowers with extraordinary polymorphism in flower tube length (Proc. R Soc. Their initial work suggests that indeed, increased flower tube length may be favoured by natural selection. The researchers have been studying a population of the plant species Gladiolus longicollis which grows in southern Africa. Northern populations tend to have longer flower tubes up to 130 mm long whereas southern populations tend to have shorter tubes as little as 35 mm. But in the boundary region between these two main populations, groups exist showing a high degree of polymorphism on flower tube length. The major pollinator appeared to be a species of hummingbird hawkmoth, Agrius convolvuli, caught using light traps, and the only moth to show tongue lengths greater than 45 mm. Around 80 per cent of moths examined carried pollen from G. longicollis. Fruit set and flower length were also measured from a group of almost 300 plant speciments growing in the study area. The results revealed that plants producing longer flowers produced significantly more fruits than shorter flowers. So why don't all plants produce long flowers? The researchers think that gene flow from the long-and short-flowered populations may mask the effects of natural selection at this site and that shorter-tongued hawkmoths may play a significant pollinator role amongst the shorter-flowered population. However, there is no doubt Darwin would have been delighted at these results and the researchers are now planning a detailed study across a much larger geographical area to check the the preliminary details so far revealed. Size matters: the length of flower tubes in Gladiolus longicollis at a site in South Africa has been shown to corrolate with breeding success in work recently reported. (Photo: R Alexandersson).
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When Push Comes to Shove:
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ورودعنوان ژورنال:
- Current Biology
دوره 12 شماره
صفحات -
تاریخ انتشار 2002