It seems Darwin's finches are making the news again. This time it appears a new species may have emerged. It is a little early to tell but the point of when exactly a new species occurs is not entirely certain.
This news comes from a very famous couple as far as Darwin's finches go, Peter and Rosemary Grant. The Grants have been working closely with Darwin's finches for the past 35 years. The story begins when a very different bird flew into their nets in 1981. This bird was a male medium ground finch, Geospiza fortis, who flew in from a neighboring island. He “was unusually large, especially in beak width, sang an unusual song” and had a few gene variants that could be traced to another finch species, the Grants wrote. This bird found a mate, who also had a few different genes, and they had 5 sons.
All 5 sons were exposed to their father's song during their critical period. Their father had attempted to copy the "local song" but had essentially made his own song in the process. The sons therefore also developed a strange song but nonetheless were able to find mates. Drought struck the island after the family of birds had gone through a couple of generations. Only a brother and sister remained. They mated and their children did the same.
Since then at least 3 generations of reproductive isloation have occurred. The Grant's feel it is now safe to say that these birds can be classified as an emerging species. The main factor in the whole speciation process was that the male sang a different song. The 1 male turned into 5 males with a different song, so on and so forth. Because a male's song has a very prominent effect on female mate choice these birds were quickly reproductively isolated. However the fate of this "species" is not certain. Many factors including, but not limited to, inbreeding depression (founder effect), genetic drift, and natural disasters may have a very negative effect on these birds in the future.
http://www.wired.com/wiredscience/2009/11/speciation-in-action/
- Jillian O'Keefe
In the picture at the top of the article the bird on the left is Daphne Major's native medium ground finch. The bird on the right is the newcomer that came to the island in 1981.
It is hard to determine when a group of "different" birds becomes a "species." This is because many biologists still do not agree on exactly what a species is. Most textbooks follow Ernst Mayr's definition of a species as "groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups" (which integrates the Biological Species Concept). So because the aforementioned finches have been reproductively isolated from Daphne Major's native medium ground finches for a few generations the Grant's feel it is appropriate to call the newcomer finches a species.
It's always reassuring to see natural selection in process. I find that the ability to show the world such a simple example of speciation makes evolution less about witchcraft and heresy and more about really...really basic processes of life.
ReplyDelete- Deysha Rivera
This article is really great. It's hard to show natural selection to people because it is something that happens over such extended time periods but to have proof available like this today is a great learning/teaching tool for the subject. I think Darwin would be very proud to see his ideas and theories being still today expanded on and solidified. What exactly will it take for the bird to be declared a new species or is it actually done already, I wasn't really sure if you had answered that in the article. Thanks!
ReplyDelete~Jessica Abu-Hijleh
I found this article to be awesome. I have learned so much about Darwin’s finches, and now hearing that a new species may have formed seems to be astonishing. this is a great example if natural selection. great article!
ReplyDelete-Stephen Chiricosta
I just learned about the Grants in my animal behavior class. It's so interesting that they helped support the theory of evolution/natural selection by actually observing it in real life. Witnessing this in real life is great evidence to change this "theory" into accepted fact. How long do the Grants predict it will take for this finch to emerge as a new species?
ReplyDelete-Tricia Carlson
Natural selection has been enforced in so many of my biology classes that I didn't realize it was still only a theory. I think it is accepted by the majority these days, but it is really interesting to see it happen within our lifetime. Does this new species of bird only differ from the previous species because they sing a different song, or are there other differences? Also, due to the drought, did that species of bird become extinct? Or are there more of that same species elsewhere in the world?
ReplyDelete-Crystal Young
What a great article choice! : ) Do you know if it has officially been names a new species? Also, looking at the pictures above, why is one beak yellow and another black do you think? Why would that change/be selected for? This is really cool.
ReplyDelete-Alyson Paige
This article is rather interesting. I have not heard any new news on Darwin’s Finches in a long time. What interested me most about this article was the ability for the offspring to mate even though they did not learn the local species song. Do you know if the song the offspring sang was better for sexual selection? Were these offspring selected for higher fitness because of this song complexity?
ReplyDeleteCarlos Varela
This article was great, I actually saw a poster/flyer for something similar posted up near the BCRC. Do scientists know about any trends in changes the beaks are currently undergoing that have to do with modern environmental changes?
ReplyDeletePosted by Heather Gore