CONSISTENCY AND VARIATION IN PHENOTYPIC SELECTION EXERTED BY A COMMUNITY OF SEED PREDATORS
Article first published online: 6 AUG 2012
© 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.
Volume 67, Issue 1, pages 157–169, January 2013
How to Cite
Benkman, C. W., Smith, J. W., Maier, M., Hansen, L. and Talluto, M. V. (2013), CONSISTENCY AND VARIATION IN PHENOTYPIC SELECTION EXERTED BY A COMMUNITY OF SEED PREDATORS. Evolution, 67: 157–169. doi: 10.1111/j.1558-5646.2012.01736.x
- Issue published online: 4 JAN 2013
- Article first published online: 6 AUG 2012
- Accepted manuscript online: 16 JUL 2012 01:45PM EST
- Received March 29, 2012, Accepted June 28, 2012, Data Archived: Dryad doi:10.5061/dryad.7q341
- Geographic mosaic of coevolution;
- lodgepole pine;
- seed predation;
- species interactions;
- trait-mediated indirect effects
Phenotypic selection that is sustained over time underlies both anagenesis and cladogenesis, but the conditions that lead to such selection and what causes variation in selection are not well known. We measured the selection exerted by three species of predispersal seed predators of lodgepole pine (Pinus contorta latifolia) in the South Hills, Idaho, and found that net selection on different cone and seed traits exerted by red crossbills (Loxia curvirostra) and cone borer moths (Eucosma recissoriana) over 10 years of seed crops was similar to that measured in another mountain range. We also found that the strength of selection increased as seed predation increased, which provides a mechanism for the correlation between the escalation of seed defenses and the density of seed predators. Red crossbills consume the most seeds and selection they exert accounts for much of the selection experienced by lodgepole pine, providing additional support for a coevolutionary arms race between crossbills and lodgepole pine in the South Hills. The third seed predator, hairy woodpeckers (Picoides villosus), consumed less than one-sixth as many seeds as crossbills. Across the northern Rocky Mountains, woodpecker abundance and therefore selective impact appears limited by the elevated seed defenses of lodgepole pine.