Schlumpberger, Boris O. , McDade, Lucinda A. , Raguso, Robert A. .
Mixing up floral traits: Radiation of Andean Echinopsis ancistrophora (Cactaceae).
The members of the Echinopsis ancistrophora group (Cactaceae) grow along the eastern slopes of the Andes, in northern Argentina and southern Bolivia. A remarkable characteristic of these plants is the variety of combinations of floral traits found in different populations. According to the classic understanding of floral ‘syndromes’, some members of the E. ancistrophora group may be pollinated by hawkmoths (long, white flowers), others by bees (short, colorful flowers). However, all other possible combinations of characters are found in nature as well, from short, white diurnal flowers to pink and partly nocturnal flowers with 20 cm length, not fitting in the classic syndromes. These findings suggest ongoing adaptations to different pollinator groups in different mountain habitats.
Our studies in 16 populations in Argentina and Bolivia demonstrate a correlation between flower length, anthesis time and quantity of nectar production. Flower color and odor are associated with each other but are not linked to flower length. Evidence for hawkmoth pollination was only found in a few populations, in which flower length, color, nectar production, odor and anthesis time met the typical syndrome for hawkmoth pollination. All other populations proved to be pollinated by bees. Odor analysis revealed more than 80 compounds, mostly sesquiterpenoids. Wind tunnel experiments demonstrated that the odor of single white flowers can serve as a distance attractant for hawkmoths, but that the odor of single colored flowers has no effect. Molecular data from chloroplast DNA suggests convergent evolution of certain combinations of floral traits, and that former attempts to define taxa mainly based on floral characters do not accurately reflect the relationships among these plants.
1 - Academy of Natural Sciences, Botany, 1900 Ben Franklin Parkway, Philadelphia, Pennsylvania, 19103, USA
2 - University of South Carolina, Department of Biological Sciences, Coker Life Sciences Building, 700 Sumter St., Columbia, South Carolina, 29208, USA
Presentation Type: Paper
Location: Wasatch (Cliff Lodge)
Date: Monday, August 2nd, 2004
Time: 1:45 PM