ON THE SCENT OF STANDING VARIATION FOR SPECIATION: BEHAVIORAL EVIDENCE FOR NATIVE SYMPATRIC HOST RACES OF RHAGOLETIS POMONELLA (DIPTERA: TEPHRITIDAE) IN THE SOUTHERN UNITED STATES
Version of Record online: 16 APR 2012
© 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.
Volume 66, Issue 9, pages 2739–2756, September 2012
How to Cite
Powell, T. H. Q., Cha, D. H., Linn, C. E. and Feder, J. L. (2012), ON THE SCENT OF STANDING VARIATION FOR SPECIATION: BEHAVIORAL EVIDENCE FOR NATIVE SYMPATRIC HOST RACES OF RHAGOLETIS POMONELLA (DIPTERA: TEPHRITIDAE) IN THE SOUTHERN UNITED STATES. Evolution, 66: 2739–2756. doi: 10.1111/j.1558-5646.2012.01625.x
- Issue online: 4 SEP 2012
- Version of Record online: 16 APR 2012
- Accepted manuscript online: 21 MAR 2012 09:15PM EST
- Received October 25, 2011 Accepted February 29, 2012 Data Archived: Dryad doi:10.5061/dryad.bn52n3br
- Ecological speciation;
- flight tunnel;
- fruit odor discrimination;
Standing variation can be critical for speciation. Here, we investigate the origins of fruit odor discrimination for Rhagoletis pomonella underlying the fly's sympatric shift in the northeastern United States from downy hawthorn (Crataegus mollis) to apple (Malus domestica). Because R. pomonella mate on host fruit, preferences for natal fruit volatiles generate prezygotic isolation. Apples emit volatiles that appear to be missing from gas chromatography/electroantennographic detection profiles for flies infesting downy hawthorns, raising the question of how R. pomonella evolved a preference for apple. In the southern United States, R. pomonella attacks several native hawthorns. Behaviorally active volatile blends for R. pomonella infesting southern hawthorns contain the missing apple volatiles, potentially explaining why downy hawthorn flies could have evolved to be sensitive to a blend of apple volatiles. Flight tunnel assays imply that southern hawthorn populations were not the antecedent of a preassembled apple race, as southern flies were not attracted to the apple volatile blend. Instead, behavioral evidence was found for southern host races on native hawthorns, complementing the story of the historical sympatric shift to introduced apple in the North and illustrating how R. pomonella may evolve novel combinations of agonist and antagonist responses to volatiles to use new fruit resources.