Oh, Those Crafty Columbines

What Would Darwin Think?

Aquilegias, or columbines, have been around for a long, long time.  According to the AHS Encyclopedia of Perennials (2007) the var. stellata, (a well-known one is 'Ruby Port') was listed as early as 1629 by John Parkinson, and the var. flore-pleno (today's Bonnet series) was described by John Gerard in 1597.

And scientists for years have been fascinated by the columbine's development.  Wild aquilegia of different types evolved in different parts of the world, but when they are grown next to each other in the same garden, those naughty things hybridize freely.  They also have the ability to pollinate themselves and still produce variation in color, size, and the form of the flower.  Whew!

And now, researchers at the University of California have found that columbines over the years have also developed certain features in response to the pollinators that are attracted to their nectar.  According to Scott Hodges of U-C Santa Barbara, Charles Darwin postulated that plants with the longest nectar spurs and pollinators with the longest tongues would be favored by the evolutionary process, continually driving nectar spurs and the tongues of pollinators to exceptionally long lengths.  Aha! But Darwin was wrong on this one.

In a study sponsored by the National Science Foundation, Hodges and Justin Whittall of U-C Davis found that plants evolve nectar spurs in response to match the lengths of each pollinator's tongue.  Thus, some columbines have nectar spurs that are perfect for hummingbirds, others have spurs that bring on the bumblebees and hawkmoths. The full results of the study appear in last week's issue of the journal Nature.

The researchers found that changes in the nectar spur length of columbines happened during shifts in pollinators from bumblebees to hummingbirds, and from hummingbirds to hawkmoths.  In between these shifts, the evolution of nectar spur length came to a dead stop.

William Zamer, deputy director of NSF's division of Integrative organismal systems, says the experiment provides evidence that evolution may occur in a stop-and-go manner, changing only when a shift occurs in pollinators.  "In the case of these flowers," he said, "changes appear to happen relatively rapidly in response to changes in pollinators."

And if any of you out there don't believe in evolution ...

(image: S.A. Hodges, M.A. Hodges, D. Inouye)

 

Comments

[kate]

This is fascinating ... Columbines are amazing plants. I have watched them in my garden turn various colours, the latest ones being entirely deep purple with their neighbours being a shell pink colour. I wonder what next year will bring.