Tuesday, August 28, 2012

Darwin's finches

Darwin's Finch
Photo lightmatter/ Flickr
Natural selection is one of the major scientific discoveries that has had major impact on humanity's understanding of deepest questions of life, its origins and evolution. It is remarkable how this major breakthrough changing the course of science had quite humble beginnings with a man observing little birds living in far away islands. (Compare this to a monk who was observing simple green peas in the quiet monastery gardens and discovering in them significant laws of genetics and heritage).
Darwin's finches (also known as the Galápagos finches) are a group of about 15 species of passerine birds. They often are classified as the subfamily Geospizinae or tribe Geospizini. It is still not clear which bird family they belong to, but they are not related to the true finches.

They were first collected by Charles Darwin on the Galápagos Islands during the second voyage of the Beagle. All are found only on the Galápagos Islands, except the Cocos Island Finch from Cocos Island. The term Darwin's Finches was first applied by Percy Lowe in 1936, and popularised in 1947 by David Lack in his book Darwin's Finches.

The birds vary in size from 10 to 20 cm and weigh between 8 and 38 grams. The smallest are the warbler-finches and the largest is the Vegetarian Finch. The most important differences between species are in the size and shape of their beaks, and the beaks are highly adapted to different food sources. The birds are all dull-coloured.

Dr Robert Rothman writes about symbol of evolution
If the giant tortoise is the symbol of the Galapagos Islands, then Darwin's finches must be the symbol of evolution in the Galapagos. It may seem curious that of all the animals in the Galapagos,this group of very drab and dull birds is most closely associated with Darwin's name. He was neither the first to see them (they are mentioned in passing by Captain James Colnett in 1798) nor did they figure much in his writings subsequent to the "Voyage of the Beagle". Despite the fact that they intrigued Darwin, they are far too complex a group of animals for Darwin to have understood. Nevertheless, they played an important role in helping him recognize the reality of the evolutionary process. The name was first applied in 1936, and popularized in 1947 by the ornithologist David Lack, who published the first modern ecological and evolutionary study of the finches. Today Darwin's finches are the subject of intense study, and they are revealing much about the evolutionary process.
Rothman Galapakos

...but Dr John van Wyhe disperses a myth
The Grant Museum warmly invites you to:
The 11th Annual Robert Grant Lecture
Rediscovering Darwin: The real story of Darwin's finches
Dr John van Wyhe
Wednesday 14th November 4.30pm (2007)

Since 1982 we have known that Darwin did not discover evolution in the Galapagos Islands when he saw the specially adapted beaks of the finches which now bear his name. But one question has remained unanswered, if Darwin did not invent the story, who did? This lecture will reveal the unexpected origins of one of the most popular myths about Charles Darwin.

Dr John van Wyhe is a Darwin historian at the University of Cambridge. He is founder and Director of Darwin online and a Bye-Fellow of Christ's College. He is co-editing a volume of Darwin's Beagle field notebooks and editing a volume of Darwin's complete shorter publications for 2009. His recent research has revealed that Darwin did not delay publishing his theory for many years after its discovery.
Wyhe Dispersal 

Medium-ground Finch
Photo  putneymark/Flickr

Natural selection only?
In this blog I try to learn more about Darwin's finches and the ideas in evolutionary biology they have inspired. For I find it interesting that these birds do not live in strikingly different environments that would demand different strategies for survival. Rather, the isolated group of islands seems to me a very homogeneous natural environment considering climate, geology and geomorphology, soil quality, plants and animals. The polymorphism of the finches beaks does therefore not appear to be the result of only a single factor, natural selection of the fittest to survive under changing environmental conditions.

Natural biodiversity may rather be a fundamental characteristic of life itself seeking many possible ways of utilizing natural resources to flourish. Natural selection is certainly an important but probably not the only factor in this marvellous richness of the works of God of Israel.

You are most welcome to join the not so ornithological discussion in this blog!