Charles Darwin pioneered the scientific movement which would become the study of evolution. Today, scientists still perform regular experiments to further understand this biological phenomenon. A couple of weeks ago, The New York Times reported that studies on koala retroviruses have illuminated the connection between virus and evolution.
Koala retroviruses, which are in the same family as H.I.V., pass contagiously and intergenerationally. These viruses insert themselves into the DNA of the host through RNA replication and slightly alter the genetic code. Once passed on to offspring, this “fake DNA” becomes “endogenous” and stops causing the original problems it had in the parent. This cycle catalyzes the evolutionary process, especially because koalas already have ancient viruses embedded in their DNA from millions of years ago. The new retroviruses koalas are infected with today activate the ancient viruses, causing a whole host of changes.
In one interesting study, scientists found that koalas in the southern part of Queensland, Australia had fewer chlamydia infections, and therefore fewer retroviruses infecting their DNA—or so they thought. When the scientists tested the DNA of the more dominant, southern population of koalas, they found that the koalas did have segments of the retrovirus in their DNA, but it was damaged. This find implies the DNA’s “immune system” may have improved the southern koalas’ survival rates. Evolutionary biologists are still studying the effects of retroviruses on DNA, and what implications they have on species survival and evolution.