Dr. Boris O. Schlumpberger DFG-funded project "Evolution of pollinator specialization and despecialization in Echinopsis (Cactaceae, Trichocereeae)" When plant species disperse to new habitats, they often encounter a new pollinator fauna and undergo changes in floral morphology resulting from divergent pollinator selection regimes. This is thought to contribute to species formation when the divergent forms later come into secondary contact but can no longer produce fit offspring. The proposed research will examine pollination in six small clades of Cactaceae, each with a 3-5 very closely related species (divergent sets of populations), in order to examine which morphological and physiological flower traits correlate with shifts between bee, hummingbird, and hawkmoth pollination. The focal clades, which belong to the large genus Echinopsis (Trichocereeae), were selected because preliminary data suggest that pollinators play a role in species divergence and reproductive isolation; there are also cases of apparent bimodal pollination strategies. We hypothesize that shifts from hawkmoth to bee pollination are relatively easy, while shifts from bee to bird or hawkmoth pollination are more difficult. All three pollination syndromes involve numerous traits besides the actual rewards (nectar and/or pollen), and this project will focus on changes in floral scents that correlate with the six possible directions of pollinator change. By focusing on several small clades we will be able to combine field observations at several sites with species/population-level phylogenetic analyses and biochemical analyses of floral odor. Together, these components will allow to assess whether more derived (younger) species tend to rely on fewer pollinators and thus are more specialized or whether on the contrary they rely on more kinds of pollinators and thus stay, or become, unspecialized. This will be only the second study to address this question and the first to assess the role of odor bouquets in the broadening or narrowing of pollinator spectra. For enlargement (1488 x 1025 pixels = 359,268 bytes) click on the poster.