Systematics/Phytogeography / Taxonomie/ Section
Baker, David , Manning, John C. , Goldblatt, Peter , Nanni, Ingrid , Conrad, Ferozah , Forest, Felix L. .
Systematics and speciation in genus Lapeirousia (Iridaceae) in the Greater Cape Floristic Region, South Africa.
Identifying the patterns and causes of speciation is fundamental to understanding the origin of biodiversity and its conservation. This is especially relevant in the Greater Cape Flora region of South Africa, an area corresponding to the southern African winter-rainfall zone, renowned for its uniquely rich plant diversity (about 80% of the ca. 12,000 species are endemic to the area). This area of about 130,000 square kilometers is less than half the area covered by California, but contains more than twice the number of species. Several, widely debated reasons have been proposed to account for the remarkable biodiversity of the region (gradual aridification, fire regimes, edaphic factors, pollinator shifts, etc). The present research proposes to examine several of these putative causal factors using genus Lapeirousia (Iridaceae; Crocoideae) as a case study. Lapeirousia, known locally as Painted Petals, comprises 41 species and is one of the few genera of African Iridaceae that is well represented in both the winter-rainfall area of southern Africa and in the summer-rainfall area of eastern and tropical Africa. The species of Lapeirousia are segregated almost equally among two subgenera with strikingly different centers of diversity; subgenera Paniculata, most diverse in subtropical Africa, and Lapeirousia, mostly restricted to the west coast and near interior of southern Africa. Using plastid DNA sequence data, we found that subgenus Lapeirousia is nested in a paraphyletic subgenus Paniculata. All Lapeirousia species are seasonal geophytes but their flowers show a great range of morphological variability, reflecting a diversity of pollination systems. The great variability of floral morphology, pollination syndromes, and edaphic preferences that is found in subgenus Lapeirousia, combined with the variation in distribution patterns between species, makes it an ideal case study for exploring various hypotheses about the causes of speciation in the winter-rainfall region of southern Africa.
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1 - Royal Botanic Gardens, Kew, Jodrell Laboratory, Richmond, Surrey, TW9 3DS, United Kingdom
2 - South African National Biodiversity Institute, Kirstenbosch Research Centre, Private Bag X7, Claremont, 7735, South Africa
3 - Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri, 63166-0299, U.S.A.
plastid sequence data
Cape Floristic Region.
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, July 29th, 2008
Time: 1:30 PM