Results of Long Term Study in Diplacus 1995 ... 2025
Population monitoring at Rainbow Canyon Road (33.450xxx, -117.131xxx)
All plants (≈ 20) were well over ten years old at monitory start in 1998. No seedling older than three years were seen within this observation period. The plants successively became darker color shades. Only orange and red flowering plants but no more yellow flowers were seen at the end of this observatory period in 2006.
Arrow: Single plant (RBA) in Transition from orange-yellow (1998) to orange-red floral color (2006).
The speed with which the populations change their character is impressive. Eight to ten years are enough to alter the appearance of a plant population. The long-lived plants are not replaced by younger ones, they change individually morphologically and genetically. The plant will change not only the color of its flowers but also its shape. The driving force could be found in the climatic conditions - it gets warmer, and with the accompanying circumstances, as the hummingbird as a potential pollinator becomes more and more frequent. But does this happen by chance, or is the trigger the environmental pressure acting on these systems? Since the whole thing is triggered by plants, which change during their lifetime, the selection theory takes precedence over it as a possible explanation. An epigenetic (lit1) approach is a more probable scenario that is plausible unless a fundamental genetic difference between the two forms with yellow and red flowers can be discerned. However, T27 and T30 may well be affected by frequent non-stochastic somatic mutations, which may somehow being passed onto the next generation lit2, as described in a later chapter.
A genetic (lit3) variation between the red and the yellow-flowered morph has recently been discovered so that neither the selection theory nor the epigenetic approach is a reasonable explanation. Another method must, therefore, be found that better describes the phenomenon.