Tuesday, November 20, 2018

Geneticist Solves Long-standing Finch Beak Mystery

Years have been spent trying to figure out why some finches have small beaks and some have large. Tom Smith has dedicated his career to studying finches. In the past, Smith discovered that the inheritance of the finches beak size was as simple as some of the Punnett squares that we have learned about in class using Mendelian genetics. The dominant trait is a large beak. Therefore, two small-billed parents would be homozygous recessive and would only produce small-billed offspring. If the parents were heterozygous they could have a mix of small-billed and large-billed offspring. It is mentioned in the article that "traits rarely show such a clean pattern of inheritance", like it did in these finches (Princeton University). After Smith found out this information about the inheritance of the beaks of finches, he wanted to find the exact gene responsible for beak size.
Smith requested help from a Princeton assistant professor named Bridgett vonHoldt, who normally works with dogs and wolves. In recent research, she found a gene in birds, called IGF-1 that is a gene also found in dogs. In dogs, this gene is a growth-factor gene. Different expressions of the gene cause different sizes. Also, if the gene is expressed more the dog may be bigger, or if it is expressed less, the dog may be smaller. Since the finches are almost completely the same as other finches, other than their beak size (body size is the same), the researchers believe that this may be the gene that changes the size of the finches beaks. It is interesting that vonHoldt, who specializes in dogs and wolves, found the same gene that she's found in dogs, in birds. I find it fascinating that the same gene, or genes that are so similar, can be found in different species.


Princeton University. "Geneticist solves long-standing finch beak mystery: Bridgett vonHoldt found a single genetic key that unlocked beak size in a central African finch species." ScienceDaily. ScienceDaily, 19 November 2018. <www.sciencedaily.com/releases/2018/11/181119064118.htm>.

“Insulin-like Growth Factor 1.” Wikipedia, Wikimedia Foundation, 31 Aug. 2018,

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