Physiological differences among two Penstemon species and their hybrids in field and common garden environments
Article first published online: 17 OCT 2008
© The Authors (2008). Journal compilation © New Phytologist (2008)
Volume 181, Issue 2, pages 478–488, January 2009
How to Cite
Kimball, S. and Campbell, D. (2009), Physiological differences among two Penstemon species and their hybrids in field and common garden environments. New Phytologist, 181: 478–488. doi: 10.1111/j.1469-8137.2008.02654.x
- Issue published online: 16 DEC 2008
- Article first published online: 17 OCT 2008
- Received: 19 May 2008; Accepted: 4 September 2008
- common garden;
- elevational gradient;
- hybrid zone;
- water use efficiency
- • Hybrids can exhibit unique combinations of the physiological traits of their parents. These particular combinations may influence hybrid fitness and the evolutionary trajectory of a hybrid zone.
- • Here, a hybrid zone between Penstemon newberryi and Penstemon davidsonii along an elevational gradient was examined, and physiological traits of parents and hybrids were measured in their native environment and a common garden. Gas exchange rates of nine different crosses were also measured.
- • Alpine P. davidsonii had less negative pre-dawn water potential and lower water use efficiency (WUE) than its montane relative P. newberryi in a common garden and in field measurements. The species difference in WUE was attributable to lower conductance in P. newberryi in the field, but to a higher photosynthetic rate in this species in the common garden. The alpine species took less time to produce mature fruits and reached maximum photosynthetic rate at a lower temperature. Natural hybrids were intermediate for most characters. F1 hybrids had lower conductance than progeny of natural hybrids.
- • The intermediate WUE of natural hybrids may be one factor that allows them to persist in intermediate environments. Comparisons of different crosses suggest that the genotypic composition of hybrids influences their physiological performance.