Tuesday, February 17, 2015

Gene that Shaped the Evolution of Darwin's Finches is Discovered

In light of Charles Darwin’s birthday a study that identified the gene that controls beak size in the Galapagos finches was published on February 11, 2015, just one day before Darwin’s birthday. The study, which was undertaken by researchers at Princeton University and Uppsala University, highlights the genetic aspects of evolution as well as gene flow and speciation. More specifically, it was discovered that evolution occurs in halting and disordered steps, allowing for genes to spread and create new lineages. Eventually the new lineages can evolve into entirely new species given the right set of circumstances.


DNA samples from 120 birds were collected and the genomes of the birds were studied. Each of Darwin’s 15 species of finches was represented in the population of the 120 birds. After studying the genomes the researchers noted a stretch of DNA that was different in finches with blunt beaks and in finches that had sharp, pointed beaks. A gene, ALX1, was found within that section of DNA. In humans and mice this gene influences the development of facial features. If this gene mutates and becomes inactivated then severe abnormalities in humans can result. However, mild mutations of this gene have the opposite effect in the finches. Instead these mutations lead to observable evolution in the finches. It was also found that individual birds of the same species sometimes had different forms of the gene. Of course, this finding is huge as natural selection runs off of genetic variation and cannot occur without it and natural selection is a means through which evolution happens.

Having studied the finches for forty years the researchers on this study know that the size and shape of the finches’ beaks plays an immense role in their survival, just as Darwin did.  They realized that the tough environment that these birds are exposed to made it essential that the finches had appropriate beaks that were suited to their habitat. However, until this study was conducted the researchers did not understand the genetic aspect of the evolution of these finches.  

Along with locating the gene that plays a role in the evolution of these finches the study also provides more information about what happens when genes are passed from one species to another (between two closely related species). Usually, the offspring of these two closely related individuals would be sterile, but that is not the case with the finches. The offspring can mate with individuals from either of the two parental species. The baby finch will conform to one of the parental species based on song and appearance. However, the finch still contains genes from both parents. This process, known as gene flow, has given the researchers a better picture of how genes move from specie to specie and create new species.

I think that this is really interesting and I haven’t thought much about it. It never really occurred to me that all of Darwin’s work was observed and he of course had no idea what genes were and which genes were playing a role in evolution. It is surprising to me that it has taken researchers so long to discover this about the finches, but it was nice that they published the study near his birthday. Honestly, I didn't think anyone still cared about the finches and didn't know that they were still being researched. It just shows that the Galapagos Islands offer many interesting species to study and that even though evolution has been studied so much there is still so much to learn. 


1 comment:

  1. I have personally read On the Origin of Species and based on the technology we have today, Darwin was living in the stone age. He was very smart and he was able to see these correlations and infer better than a lot of people can nowadays despite the technology and further research. I will never for the life of me understand people who don't see any credibility in evolution because without it, we'd all still be little single-celled organisms swimming around somewhere.

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