Interspecific competition alters natural selection on shade avoidance phenotypes in Impatiens capensis
Article first published online: 1 JUL 2009
© The Authors (2009). Journal compilation © New Phytologist (2009)
Special Issue: Plant adaptation - following in Darwin's footsteps
Volume 183, Issue 3, pages 880–891, August 2009
How to Cite
McGoey, B. V. and Stinchcombe, J. R. (2009), Interspecific competition alters natural selection on shade avoidance phenotypes in Impatiens capensis. New Phytologist, 183: 880–891. doi: 10.1111/j.1469-8137.2009.02934.x
- Issue published online: 17 JUL 2009
- Article first published online: 1 JUL 2009
- Received: 13 May 2009Accepted: 22 May 2009
- canonical analysis;
- Impatiens capensis;
- natural selection;
- phenotypic plasticity;
- shade avoidance syndrome
- • Shade avoidance syndrome is a known adaptive response for Impatiens capensis growing in dense intraspecific competition. However, I. capensis also grow with dominant interspecific competitors in marshes. Here, we compare the I. capensis shade-avoidance phenotypes produced in the absence and presence of heterospecific competitors, as well as selection on those traits.
- • Two treatments were established in a marsh; in one treatment all heterospecifics were removed, while in the other, all competitors remained. We compared morphological traits, light parameters, seed output and, using phenotypic selection analysis, examined directional and nonlinear selection operating in the different competitive treatments.
- • Average phenotypes, light parameters and seed production all varied depending on competitive treatment. Phenotypic selection analyses revealed different directional, disruptive, stabilizing and correlational selection. The disparities seen in both phenotypes and selection between the treatments related to the important differences in elongation timing depending on the presence of heterospecifics, although environmental covariances between traits and fitness could also contribute.
- • Phenotypes produced by I. capensis depend on their competitive environment, and differing selection on shade-avoidance traits between competitive environments could indirectly select for increased plasticity given gene flow between populations in different competitive contexts.