Abstract Detail



Reproductive Processes

Majetic, Cassie [1], Castilla, Antonio [2], Levin, Donald [3].

Losing a “scent” of one’s “self”: is there a reduction in floral scent emission in self-pollinating Phlox cuspidata vs. outcrossing Phlox drummondii?

Studies of the evolution of self-pollination have generally predicted reductions in pollinator-attractive morphological floral traits over time as a result of relaxed pollinator-mediated selection and/or positive selection associated with improved self-pollination due to smaller size.   Non-morphological traits, such as floral scent, may also become reduced in self-pollinating taxa due to relaxed pollinator-mediated selection.  However, evidence for such reductions in floral scent of selfing vs. outcrossing taxa is limited. We explored this possibility in the scent of the predominantly selfing taxa Phlox cuspidata and its close outcrossing relative Phlox drummondii using dynamic headspace extraction and gas chromatography-mass spectroscopy.  Scent emission rates were compared between species and among populations nested within species via MANOVA.  Of the 37 scent variables examined, only three showed significant differences between species.  However, all three were emitted in decreased quantities from selfing P. cuspidata.  Emission rates of six additional scent variables also differed among populations, as is common for other plant species. While our findings suggest some support for reductions of scent emission in selfing vs. outcrossing annual Phlox, the retention of substantial scent production, with notable among-population variation, by P. cuspidata suggests continued dependence on pollinators (for either outcrossing or facultative selfing).  This is further supported by maintenance of a pollen to ovule ratio similar to outcrossing P. drummondii and showy floral traits, as well as past research emphasizing the importance of floral color in pollinator-mediated evolution. The retention of significant terpenoid emission alternatively suggests potential defensive functions for floral scent, as these compounds are known to have anti-herbivore and anti-pathogen properties.  Future research should examine both possibilities.


1 - Saint Mary's College, Dept Of Biology, SR 933 North, Notre Dame, IN, 46556, United States
2 - Instituto Superior de Agronomia, Universidade de Lisboa, Centro de Ecologia Aplicada Prof. Baeta Neves/InBIO, Tapada da Ajuda, Lisbon, Portugal
3 - Section Of Integrative Biology, Austin, TX, 78713, United States

Keywords:
Phlox drummondii
Phlox cuspidata
floral scent
self-pollination
outcrossing
Pollination biology.

Presentation Type: Oral Paper
Number:
Abstract ID:244
Candidate for Awards:None


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