Study of flower color shows evolution in action

Jun 29, 2009
This is the Rocky Mountain Columbine. Credit: R. Kelly Dawe

Scientists at UC Santa Barbara have zeroed in on the genes responsible for changing flower color, an area of research that began with Gregor Mendel's studies of the garden pea in the 1850's.

In an article published recently in the Proceedings of the National Academies of Sciences, two researchers document their studies of the evolution of columbine flowers in North America. They studied red columbines pollinated by hummingbirds, and white or yellow columbines pollinated by hawkmoths. They believe that a color shift from red to white or yellow has happened five times in North America.

"What is important in this research is that hawkmoths mostly visit -- and pollinate -- white or pale flowers," said senior author Scott A. Hodges, professor of ecology, evolution and marine biology at UCSB. "We have shown experimentally that hawkmoths prefer these paler colors."

This Longspur Columbine (A. longissima) has the longest nectar spurs in the genus. Credit: Scott Hodges, UCSB

When a plant population shifts from being predominantly hummingbird-pollinated where flowers are red, to hawkmoth-pollinated, natural selection works to change the flower color to white or yellow, he explained.

"Ultimately we want to know if evolution can be predictable," said Hodges. "In other words, we want to know if each time there is an evolutionary change in flower color, does it happen in the same way? Having identified all the genes that are intimately involved with making red and blue columbines now allows us to determine how these evolutionary transitions have occurred."

In earlier research, Hodges showed that evolve in a predictable fashion to match the mouthparts of pollinating birds and insects. Thus the pollinators of the yellow columbine flower, A. longissima, are predicted to have exceptionally long tongues to reach the nectar at the bottom.

Source: University of California - Santa Barbara (news : web)

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JCincy
1 / 5 (1) Jun 29, 2009
How does this demonstrate evolution?

Was new genetic information obtained by the flowers to change colors or was the information already present?

Please note that natural selection and evolution are two mutually independent processes. Observing one, doesn't verify the other.
LariAnn
2 / 5 (4) Jun 29, 2009
The title of this article is misleading, as it does not show "evolution" in action, but rather adaptation. The columbine flowers are still columbines, and the existing pollinators find the flowers which their abilities enable them to. If the population of either type of pollinator falls or rises, the amount of corresponding flowers pollinated (and seeds produced) will also change. This is basic dominant and recessive gene information that I don't believe should be slanted as more "proof" of evolution. After all, the columbine flowers are not in the process of changing into an entirely different plant; they are merely expressing within their presently existing range of genetic resources.
mabarker
1 / 5 (1) Jul 15, 2009
Three cheers for JCincy & LariAnn!! Clear & critical thinking is the rule for both of you - which is why neither 1 of you received 5 stars. *Natural selection is not Evolution* said Ronald Fisher in his book The Genetical Theory of Natural Selection. As a non-darwinist I see natural selection not as the macroevolutionist does - having the ability to *create* anything. Four evolutionary naturalists said in 1989, *NS can act only on those biologic properties that already exist; it cannot create properties in order to meet adaptational needs* - p. 516 of Parasitology (6th ed).
Keep up the good work you 2!!