AOBPreview originally published online on December 23, 2005
Annals of Botany 2006 97(3):317-344; doi:10.1093/aob/mcj040
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
INVITED REVIEW |
Radiation of Pollination Systems in the Iridaceae of sub-Saharan Africa
1 B. A. Krukoff Curator of African Botany, Missouri Botanical Garden, PO Box 299, St Louis, MO 63166, USA and 2 Compton Herbarium, South African National Biodiversity Institute, Kirstenbosch Botanic Gardens, Claremont 7735, South Africa
* For correspondence. E-mail pgoldblatt{at}oregoncoast.com
Received: 21 June 2005 Returned for revision: 12 September 2005 Accepted: 28 October 2005 Published electronically: 23 December 2005
• Background Seventeen distinct pollination systems are known for genera of sub-Saharan African Iridaceae and recurrent shifts in pollination system have evolved in those with ten or more species. Pollination by long-tongued anthophorine bees foraging for nectar and coincidentally acquiring pollen on some part of their bodies is the inferred ancestral pollination strategy for most genera of the large subfamilies Iridoideae and Crocoideae and may be ancestral for the latter. Derived strategies include pollination by long-proboscid flies, large butterflies, night-flying hovering and settling moths, hopliine beetles and sunbirds. Bee pollination is diverse, with active pollen collection by female bees occurring in several genera, vibratile systems in a few and non-volatile oil as a reward in one species. Long-proboscid fly pollination, which is apparently restricted to southern Africa, includes four separate syndromes using different sets of flies and plant species in different parts of the subcontinent. Small numbers of species use bibionid flies, short-proboscid flies or wasps for their pollination; only about 2 % of species use multiple pollinators and can be described as generalists.
• Scope Using pollination observations for 375 species and based on repeated patterns of floral attractants and rewards, we infer pollination mechanisms for an additional 610 species. Matching pollination system to phylogeny or what is known about species relationships based on shared derived features, we infer repeated shifts in pollination system in some genera, as frequently as one shift for every five or six species of southern African Babiana or Gladiolus. Specialized systems using pollinators of one pollination group, or even a single pollinator species are the rule in the family. Shifts in pollination system are more frequent in genera of Crocoideae that have bilaterally symmetric flowers and a perianth tube, features that promote adaptive radiation by facilitating precise shifts in pollen placement, in conjunction with changes in flower colour, scent and tube length.
• Conclusions Diversity of pollination systems explains in part the huge species diversity of Iridaceae in sub-Saharan Africa, and permits species packing locally. Pollination shifts are, however, seen as playing a secondary role in speciation by promoting reproductive isolation in peripheral, ecologically distinct populations in areas of diverse topography, climate and soils. Pollination of Iridaceae in Eurasia and the New World, where the family is also well represented, is poorly studied but appears less diverse, although pollination by both pollen- and oil-collecting bees is frequent and bird pollination rare.
Key words: Floral form, fragrance chemistry, guilds, keystone species, nectar chemistry, Coleoptera, Hymenoptera, Lepidoptera, Nectarinia
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  J. Ollerton, R. Alarcon, N. M. Waser, M. V. Price, S. Watts, L. Cranmer, A. Hingston, C. I. Peter, and J. Rotenberry A global test of the pollination syndrome hypothesis Ann. Bot., June 1, 2009; 103(9): 1471 - 1480. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Van Kleunen, I. Nanni, J. S. Donaldson, and J. C. Manning The Role of Beetle Marks and Flower Colour on Visitation by Monkey Beetles (Hopliini) in the Greater Cape Floral Region, South Africa Ann. Bot., December 1, 2007; 100(7): 1483 - 1489. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. P. Linder, T. Dlamini, J. Henning, and G. A. Verboom The evolutionary history of Melianthus (Melianthaceae) Am. J. Botany, July 1, 2006; 93(7): 1052 - 1064. [Abstract] [Full Text] [PDF]
|
|