High School Guest Post: Genomes Through the Ages

On Monday, I wrote about the high school science bloggers in Ms. Baker’s biology classes at Staten Island Academy. Over the next few weeks, I will be publishing several guest posts that have been written by Ms. Baker’s students.

Today’s post comes from ninth-grader Molly, who says she’d like to be a teacher or journalist someday. (Note: At Ms. Baker’s request, I am withholding the last names of the students–if you are interested in contacting any of them, Ms. Baker asks that you please get in touch with her at extremebiology@gmail.com.) I have not done any editing–the post, which begins below, is all Molly’s own work. –EA

Genomes Through the Ages
By Molly
9th Grade
Staten Island Academy

An international study conducted by the Washington University School of Medicine in St. Louis, resulted in new discoveries about human evolution as well as ape evolution over the past 20 million years ago. Scientists from all parts of the world followed author Richard K. Wilson PhD, in testing two species of Asian orangutans for DNA similarities and comparisons to humans and other related species.

The scientists used the Sumatran (Pongo abelii) and the Bornean (Pongo pygmaeus) orangutans in the study (the Human’s most distant relative), and sequenced (or decoded) their DNA to test for the diversity amongst the sequence of codons. Diversity is the ability populations have to stay healthy and adapt to environmental changes.  They used five Sumatrans and five Borneans in the study, compared to the sequence of one Sumatran’s DNA.


Evolution of Humans by mollyannnne, made at DoInk.com

According to a Nature article, first, the scientists estimated the orangutans’ average nucleotide (basic structural units that form nucleic acids in living cells) identity between both species, and their results concluded that 99.68% of the two species’ genomes were identical. Next, they tested for single nucleotide polymorphisms or in other words a single occurrence of the different forms of the individual orangutan’s DNA alignment. Complicated enough, the study simply shown that 99.0% of genotypes were identical.

Richard K. Wilson and his team of scientists also found that the there is a strong stability or diversity amongst these two organisms. Based on DNA variations (13 million), scientists have now proven that the Sumatran and Bornean orangutan have been steady and have changed a limited amount over the past 12-16 million years ago. Compared to human evolution these two species have done very little adapting or changing shown from their genetic sequences.

Scientist believe that structural changes might be deeply related to the species evolution, therefore proving why the Sumatran and Bornean have had little adaptations or structural rearrangements. More specifically, the repetitive “Alu” element is found almost 5,000 times in the human genome (a guidebook for creating and maintaining a species), and 2,000 times in the chimpanzee genome (the human’s closest cousin). However, in the orangutan’s genome the element is repeated only 250 times, meaning there have been very few insertions, deletions, or any type of variation, strengthening their genome stability.

On the other hand, besides being a genetic discovery, the study showed the severity of the two species’ endangerment. The Sumatran and Bornean orangutans live in the rain forests of southeast Asia, which is an area under great environmental pressure. Deforestation is a huge problem in rain forests, and the orangutan population is dwindling. There are only 50,000 Bornean orangutans left and 7,000 Sumatran orangutans alive in the forests today. Because these species spend almost 95% of their day in the trees (traveling, nesting, and searching for food), they are in great risk of becoming completely extinct if their habitat is destroyed.

Questions for Commenters: Are there any other apes, or monkeys (related to humans) that have more diversity than humans or have a very steady genome throughout evolution’s history? Have there been any other similar studies? What are ways to prevent the complete extinction of the Sumatran and Bornean orangutan? Have there been any successful attempts to save these animals?

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