Darwin’s Finches Mystery Solved

Since freshman biology, I have been interested in Charles Darwin’s study of the finches. It has interested me in how different sizes in beaks have been caused by natural selection and how that was prominent in society. However, I always have wondered whether something else other than natural selection creates the diversity of finches and animals. That is when I read an article and realized that Darwin was never able to learn how the finches DNA caused them to be different. However, recently scientists from Princeton and UCLA have figured out the genes that make finches beaks to be short and long in Cameroon and the Galapagos islands by studying gene sequences.

Research of finches has been ongoing for several decades after Charles Darwin died, but recently the majority of the research has been based upon the DNA and genes of finches. One study from Princeton was about how scientists have found out how the environment activates certain genes in finches that causes a preferability of certain beak shapes. In regions where droughts are very common, small shaped beaks are more common than long ones due to the gene HGMA-2. This gene was found in Geospiza fortis a type of finches in the Galapagos islands, and it is what caused medium ground finches with small beaks to survive during a drought in those islands. The reason why this gene was responsible for the survivability of these finches is that it is one of the genes in finches that are most affected by the environment and a higher presence of this gene causes finches to have shorter beaks. Not only this gene plays a role in finches, but there is another gene that plays a key role in long beak sizes.

Another study that has also influenced how genes affect finches beaks comes from finches found in Cameroon. Tom Smith from UCLA has been researching Black-Bellied Seed Crackers in Cameroon to find out what causes the distinction between short-beaked and large beaked finches in that region. He created an experiment to test these distinctions by creating a breeding colony of finches and test over time how their beak sizes are changing every generation. After several years, he took DNA samples from the finches to determine what DNA sequences causes finches to differ from each other in every generation. With the help of Bridgett Vonholdt, they analyzed the genome sequences and Mendelian patterns of finches. They found that on a stretch of DNA with 300,000 base pairs, there was always a distinction between short and long-beaked finches. The gene responsible for this DNA stretch is the gene IGF-1. This gene has a significant impact on finches because it can affect several different characteristics of finches and is key in which traits will be more expressed in finches. In the finches tested, the IGF-1 gene for finches is the only thing that differed because the finches have more of this gene present in certain regions of the genome had long-beaks while short-beaked finches had lower levels of IGF-1.

This recent discovery is significant because it plays a key role in Darwin research of finches. Not only does natural selection and environmental factors play a role in the beak sizes but the genes locations on genomes and its presence play is the heaviest role in the differentiation of beak sizes. This phenomenon explains why not all of the finches have the same beaks in one environment after several generations. These findings are similar to scientific research of invasive species and can help solve that problem because of if scientists are researching how genes affect why species are being extinct. With all this said, a scientist has solved why Darwin’s finches were so different from each other, and these findings will impact scientists everywhere.

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About Mr. Mohn

Biology Teacher

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