Jul
26
2006

Those finches are still at it

Charles Darwin, c. 1881: Source: Wikipedia (Public Domain)
Charles Darwin, c. 1881: Source: Wikipedia (Public Domain)
A group of Galapagos Island birds known as Darwin’s Finches continue to do what they’re best known for: evolving. A recent study published in the the journal Science, details how new competition for food has resulted in some rather quick adaptations in the beaks of some of the famous finches that were instrumental in Charles Darwin formulating his theory of evolution.

Finch: US Fish and Wildlife photo courtesy Wikimedia Commons
Finch: US Fish and Wildlife photo courtesy Wikimedia Commons
Peter Grant of Princeton University has been studying the finches for decades. Early on he noticed that a medium sized ground finch, Geospiza fortis, living on the Galapagos island of Daphne, faced no competition for food and ate both small and large seeds. Then, in 1982, competition arrived in the form of a larger ground finch, Geospiza magnirostris, setting in motion a classic case of microevolution.

The new species was able to break open the larger seeds of the Tribulus plants three times faster than G. fortis and soon depleted the island’s large seed supply.

Over the next twenty years the population of G. fortis finches with larger beaks declined dramatically due to the competition, leaving only a population of smaller beaked G. fortis which didn’t compete for the larger seeds favored by G. magnirostris.

What makes this unusual is that it’s given scientists a rare opportunity to actually observe first hand a change in an animal’s appearance caused by the arrival of a new food competitor.

SOURCES AND LINKS

Minneapolis Star Tribune story
Darwin’s Finches
More on Darwins’s Finches
Charles Darwin
The Galapagos Islands
Charles Darwin Foundation

Your Comments, Thoughts, Questions, Ideas

Liza's picture
Liza says:

Two really fantastic books on evolution and island biogeography (seriously! one of these was even my beach reading two years ago...):

posted on Wed, 07/26/2006 - 3:04pm
Anonymous's picture
Anonymous says:

Actually, they are not "evolving" as the term is typically used. In terms of "changing over time," then yes...they are evolving as pretty much any other species does.
However, the evolution here does not appear to be GENETIC. The majority of the change occurred over a single generation, which is far to fast for genetic evolution [especially in higher vertebrates.]
The "evolution" here appears to be due to phenotypic plasticity, which, if anything, is the exact opposite of what they are "famous for." They are famous for supporting the notion of speciation over long periods of time due to natural selection. In fact, they show change due to environmental factors causing different phenotypes developing from the same genotype...in other words Modern Lamarkism!

posted on Mon, 12/25/2006 - 6:24pm

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