Conti, Elena , Quast, Monica P. , Gaskett, Anne C. , Schiestl, Florian P. .
Floral odor variation in heterostylous primroses: effects on pollinators’ floral constancy and plant fitness.
HETEROSTYLOUS species of Primula
are characterized by the reciprocal positioning of stigma and anthers in the two floral morphs (known as pins and thrums) and a diallelic self-incompatibility system that prevents intra-morph fertilization through rejection of the pollen produced by the same morph. Successful fertilization in these species thus depends on efficient cross-pollination via insects. Therefore, it is expected that floral traits, such as odor, involved in pollinators’ attraction should show very little variation between morphs, because any divergence that caused pollinators to preferentially visit only one morph would reduce plant fitness in heterostylous species. Conversely, any changes in floral traits that affected the pollinators’ floral constancy might promote the loss of heterostyly. We investigated floral odor variation in natural populations of the heterostylous P. elatior and P. farinosa. As expected, no variation was detected between the scents of pins and thrums within each species, although the floral bouquets of the two species differed from each other. We then proceeded to artificially change the floral odors of pins and thrums of P. elatior in a garden experiment. Pins and thrums in treatment plots received different odors, whereas the morphs in the positive control plots had the same odor. As expected, we found a significant difference in the number of fruits between the morphs of the treatment as compared to the morphs of the positive control plots. Our study for the first time documents a reduction of reproductive success in a heterostylous species associated with the alteration of traits that act on pollinators’ floral constancy. Given the fundamental role of pollinators in heterostylous systems, this result has important implications for the conditions that may lead to the loss of heterostyly.
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1 - Universität Zürich, Institut für Systematische Botanik, Zollikerstrasse 107, Zürich, CH-8008, Schweiz
2 - Macquarie University, Biological Sciences, Sydney, New South Wales, 2019, Australia
3 - ETH Zürich, Institute for Integrative Biology, Universitaetsstrasse 16, Zurich, CH-8092, Switzerland
Presentation Type: Oral Paper:Papers for Topics
Date: Monday, July 31st, 2006
Time: 1:45 PM