“It's Mostly Mothers Who Pass on Mitochondria.”

Julia Pabafikos

Mr. Ippolito

AP Biology

December 5, 2017

Arunas L. Radzvilavicius, The Conversation US. “It's Mostly Mothers Who Pass on Mitochondria.” Scientific American, 5 Nov. 2017, www.scientificamerican.com/article/it-rsquo-s-mostly-mothers-who-pass-on-mitochondria/.

The article I decided to read, “It's Mostly Mothers Who Pass on Mitochondria” by Arunas L. Radzvilavicius touches upon sexual conflict, or how evolutionary interests of males and females do not always coincide. Radzvilavicius points out a factor of a study conducted for inheritance of genes located in the mitochondria, which is the structures inside our cells that breathe and produce energy. The study showed that when an egg is fertilized, only the mother’s mitochondrial genes survive, while the father’s mitochondria are lost. These results, however are not accidental, it is actually due to the fact that females have evolved many mechanisms to recognize a partner’s mitochondria when entering the egg. In the long run, inheritance of healthy maternal mitochondria is good news for the offspring. Radzvilavicius mentions fruit flies and how the father destroys most of his own mitochondria during production of sperm therefore if his mitochondria was to be passed down to his offspring it would only be detrimental. When a male fruit flies goes to reproduce with a female, he actually inject his partners with toxic chemicals which destroy sperm of the female’s previous mates in order to improve his own chances for becoming the father. However, these toxins make female flies sick and reduce their lifespan and so female fruit flies have evolved defenses to counter the chemicals. In another study, Radzvilavicius show that exceptions arise because of a sexual conflict over the control of mitochondrial inheritance. They use mathematical modeling that shows that evolution in females tends to focus on long-term effects. Destroying paternal mitochondria makes it easier to avoid harmful mutations. Lastly, Radzvilavicius mentions there is evidence that this conflict dates back to the days when all organisms were made of single cells. “One of the strategies an organism is to simply have more mitochondria than their partner by increasing the size of their sex cells, and strikingly, this might have been the impetus to evolve two sexes in the first place.” (Radzvilavicius 2017)

The development is important because it shows that females may have won this ancient battle by simply producing larger sex cells packed with mitochondria. By doing so female fruit flies can ensure that the mitochondrial transmission is effectively one-sided. This strategy works well in females, because the same healthy set of maternal mitochondria is passed down the female line over and over again. Since most of their mitochondria are replaced by maternal ones at the start of every generation, evolution cannot detect long-term benefits from males’ mitochondrial genes. “It’s these different interests of males and females that we wish to study further. Evolution in females strives to keep the future generations free of male mitochondria, while males make every effort to get some of theirs into the mix.” (Radzvilavicius 2017) Radzvilavicius mentions that although females have had the upper hand with mitochondria, males have come up with ways to subvert female destruction of their mitochondria which can further science and can affect society by establishing a way for genes to become dominant and less vulnerable.

This article was both informative and very easy to understand. Author Arunas L. Radzvilavicius did an amazing job stating the background information in order to attract his reader. He gave great examples that connected his research to many animals throughout the world and even went on to describe how sexual conflicts led to the two sexes being formed. However, I believe that the author should include even more specifics about his research and experiments in order for the audience to further understand how tedious and how important this research is for society. Additionally, Radzvilavicius mentions “Over and over again, males have come up with ways to subvert female destruction of their mitochondria,” however does not go into further detail on how males have tried to overcome the destruction of their mitochondria. I think that by adding this aspect he would be able to not only add some length to his article but also further the point of the competitiveness between the sexes.