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(Santa Barbara, Calif.) ––
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."
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 flowers 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.
Photo Credit: George
Foulsham, Public Affairs, UCSB
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