Crown depth as a result of evolutionary games: decreasing solar angle should lead to shallower, not deeper crowns
Article first published online: 18 FEB 2014
© 2014 The Author. New Phytologist © 2014 New Phytologist Trust
Volume 202, Issue 4, pages 1249–1256, June 2014
How to Cite
Vermeulen, P. J. (2014), Crown depth as a result of evolutionary games: decreasing solar angle should lead to shallower, not deeper crowns. New Phytologist, 202: 1249–1256. doi: 10.1111/nph.12729
- Issue published online: 8 MAY 2014
- Article first published online: 18 FEB 2014
- Manuscript Accepted: 19 JAN 2014
- Manuscript Received: 10 OCT 2013
- Netherlands Organisation for Scientific Research (NWO)
- game theory;
- There is a general notion in the literature that, with increasing latitude, trees have deeper crowns as a result of a lower solar elevation angle. However, these predictions are based on models that did not include the effects of competition for light between individuals. Here, I argue that there should be selection for trees to increase the height of the crown base, as this decreases shading by neighbouring trees, leading to an evolutionarily stable strategy (ESS). Because the level of between-tree shading increases with decreasing solar angle, the predicted ESS will shift to higher crown base height.
- This argument is supported by a simulation model to check for the effects of crown shape and the change of light intensity that occurs with changing solar angle on model outcomes.
- So, the lower solar angle at higher latitudes would tend to select for shallower, and not deeper, crowns.
- This casts doubt on the common belief that a decreasing solar angle increases crown depth. More importantly, it shows that different assumptions about what should be optimized can lead to different predictions, not just for absolute trait values, but for the direction of selection itself.