The article is selected below as an article found online with my NYT subscription.
Article: https://www.nytimes.com/2024/05/31/science/largest-genome-fern-plant.html?searchResultPosition=59
Citation:
Zimmer, C. (2024, May 31). Scientists Find the Largest Known Genome Inside a Small Plant. The New York Times.
Summary:
Jaume Pellicer led a team of scientists to a Pacific Island called Tmesiptersis oblanceolate. The fern was not easily identified, as it blended in with the rest of the greenery. Once found, the team retrieved samples and analyzed the genome. The conclusion, the genome is the largest on earth containing more than 50 times more DNA as a human.
The article gives an elementary explanation of transcription and translation to the reader. The original thought was that the bigger the species, the bigger the genome, but they were mistaken after weighing the genome of other smaller animals. According to the article, DNA is broken down into three sections, 1.5% is protein coding genes, 8.5 % has other important functions, and 90% is junk DNA. The amount of junk DNA varies based on the species; for Dr. Pellicer, his curiosity turned towards the large genomes of some plants relative to humans. In 2010, Dr. Pellicer discovered the Paris Japonica of Japan had the largest known genome, 148 billion pairs of DNA letters. When his team brought back the ferns to Barcelona, his graduate student identified that the new fern genome contained 160 billion pairs of DNA letters.
The article discusses two ways that genomes expand over time. First, the species makes new copies of their genomes, then makes a copy of a virus-like stretch of DNA, which continues to occur and accumulate over time. Another way is when two species mate, created a hybrid with both genomes. Despite the record-breaking genome, it may not be evolutionary favorable because of the energy required to copy such large genomes, which may be why we see such large gaps in the size of differing species genomes. Dr. Pellicer believes that scientists are at their upper limit with the size of genomes, while critics like Brittany Sutherland think since we have only sampled about 3% of plant species that the possibilities for larger genomes likely still exist.
How this article relates to genetics and supporting review article summary:
This article discusses the genomes of various species in the world, including humans, plants, and other smaller animals. The article gives an elementary discussion of transcription and translation and explains the magnitude of DNA size in various genomes. This discussion also brings question to the reasoning for junk DNA and why it can make up so much of a species genome. The sheer magnitude of genome difference, specifically 50 times greater than ours brings in to question many evolutionary questions as to why species may have a smaller genome. The article theorizes that maybe low competition and a stable climate is the only way a large genome could form. Overall, this article discusses DNA replication, genomes of various species, and the evolutionary genetic impacts on genome development. The cited article discusses some of the reasons why large genomes are found in the environment. The article explains that higher diversification rates are generally found in small genome species. They conclude based on the studies they are analyzing that large genomes may constrain speciation rate or increase extinction rate. This supports what the article written by The New York time states but adds an additional point about constraining speciation rate. The review article does not believe that extinction rate is the sole cause for the lake of small genomes. The conclusion of both the popular press article and scholarly review article conclude that there is more to be studied, and more research will allow this phenomena to be studied and the reasoning for the creation of such large genomes.
Citation:
Kraaijeveld K. Genome Size and Species Diversification. Evolutionary Biology. doi: 10.1007/s11692-010-9093-4 (2010)