Systematics Section / ASPT
Crawford, Daniel J. , Archibald, Jenny K. , Stoermer, Danielle , Mort, Mark E. , Santos-Guerra, Arnoldo .
Baker’s Law, Breeding Systems, and the Evolution of Tolpis (Asteraceae) in the Canary Islands.
The genus Tolpis (Asteraceae) in the Canary Islands consists of a monophyletic group of 12-15 endemic species (including several undescribed species) and one nonendemic species. Because a basic question in the origin and evolution of island plants is the breeding system of their ancestral colonizers and the evolution of these systems during radiation in an archipelago, we examined the breeding system of Canary Island Tolpis. With one exception, all endemic species exhibit various levels of pseudo-self-fertility (PSF), with considerable variation within some populations. A PSF ancestor would have facilitated establishment in the archipelago from a single propagule; because the propagule may then have originated from a largely outcrossing continental population, it would have carried more genetic diversity than a single dispersal from a selfing population. The condition of PSF is a possible solution to the dilemma of Baker’s law because a single propagule could establish a sexual population yet would have increased diversity to facilitate diversification in the insular setting. PSF would have been advantageous in the founding and divergence of new populations in the Canaries because novel features could have been fixed by a combination of selfing and stochastic factors. Tolpis glabrescens, the only polyploid Tolpis species in the Canaries, exhibits a wide range of PSF. True-self-fertility (TSF) has originated at least once in Tolpis in the Canaries from PSF ancestors, with T. coronopifolia having a suite of floral features (small capitula, low pollen-ovule ratios, small stigmatic surfaces) indicative of selfing. Tolpis coronopifolia occurs in a wide range of open habitats throughout the island of Tenerife. A second TSF species, Tolpis barbata, occurs on the Canary Islands as well as in continental habitats, and is the only really weedy species in the archipelago. It has not been established whether T. barbata originated in the insular or continental setting.
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1 - University of Kansas, Department of Ecology & Evolutionary Biology, Natural History Museum and Biodiversity Research Center, 1200 Sunnyside Avenue, Lawrence, Kansas, 66045-7534, USA
2 - University of Kansas, Department of Ecology & Evolutionary Biology, 1200 Sunnyside Avenue, Lawrence, Kansas, 66045-7534, USA
3 - St. Olaf College, Department of Biology, Northfield, Minnesota, 55057, USA
4 - Jardín de Aclimatación de La Orotava, Puerto de la Cruz, Canary Islands, Tenerife, Spain
Presentation Type: Oral Paper:Papers for Sections
Location: Lake Erie/Hilton
Date: Monday, July 9th, 2007
Time: 3:00 PM