Ontogenetic colour changes in an insular tree species: signalling to extinct browsing birds?
Article first published online: 14 JUL 2009
© The Authors (2009). Journal compilation © New Phytologist (2009)
Volume 184, Issue 2, pages 495–501, October 2009
How to Cite
Fadzly, N., Jack, C., Schaefer, H. M. and Burns, K. C. (2009), Ontogenetic colour changes in an insular tree species: signalling to extinct browsing birds?. New Phytologist, 184: 495–501. doi: 10.1111/j.1469-8137.2009.02926.x
- Issue published online: 25 SEP 2009
- Article first published online: 14 JUL 2009
- Received: 10 March 2009Accepted: 15 May 2009
- New Zealand;
- plant defence
- • Animals often use colours to hide from predators (crypsis) or advertise defences (aposematism), but there is little evidence for colour-based defence in plants.
- • Here, we test whether ontogenetic changes in leaf colour of lancewood (Pseudopanax crassifolius) may have been part of a defensive strategy against flightless browsing birds called moa, which were once the only large herbivores in New Zealand. We tested this hypothesis by conducting spectrographic measurements on different-sized plants grown in a common garden. We also compared these results with observations on a closely related, derived species that evolved in the absence of moa on the Chatham Islands.
- • Spectrographic analyses showed that birds would have difficulty distinguishing seedling leaves against a background of leaf litter. Conversely, brightly coloured tissues flanking spines on sapling leaves are highly conspicuous to birds. Once above the reach of the tallest known moa, adults produce leaves that are typical in appearance to adult leaves. The Chatham Island species lacks ontogenetic colour changes entirely.
- • Overall, the results indicate that P. crassifolius goes through a remarkable series of colour changes during development, from cryptically coloured seedlings to aposematically coloured saplings, which may have formed a defensive strategy to protect against giant browsing birds.