A Shark Divide

 A recent Forbes article, titled "Three Sharks, Three Fates: The Genetic Divide Of Great Whites" by marine scientist and science communicator Melissa Cristina Marquez covers new research published by scientific journal Current Biology. Researchers Isabel Wagner, Irina Smolina, Martina E.L. Koop, etc. took genetic samples of 89 different Great White Sharks, then categorized the sharks by genetic similarity.

It turns out that Great White Sharks are genetically divided into three lineages: North Atlantic, North Pacific, and Indo-Pacific. These lines rarely mix due to habitat isolation. Specifically, ocean currents keep these groups of sharks apart in different ocean basins. Yet, interbreeding is still possible. The researchers also bring into question the possibility of sharks inheriting roaming behavior, a possible reason why different shark lineages may also stay on their respective areas.

This divide, however, presents a problem for the species in that depletion of one group could not be replenished by another. Marquez mentions that the genetic divide puts the Great White Shark in real danger of extinction, especially combined with other threats, such as pollution or poaching.

Could the three different lineages of the Great White Sharks evolve into completely new species, with their own separate niches? It is possible, but unlikely that we would see it anytime soon. Or, could there only be one lineage that survives? As of now, the possibilities for where this genetic division might go are practically endless. What may be be most likely (and most cynical to reason) is that human-caused habitat destruction and poaching may result in all three lineage's deaths. Evolution is happening now, all around us, and with us. It's hard to tell what direction it may go.

Pondering aside, I would like to do more research on each type of lineage. Different lineages concentrated in each area might indicate differences in each type of shark. That could mean differences in diet, physical appearance, or it could just be genetic differences. Either way, I would like to know.

ARTICLES:

https://www.forbes.com/sites/melissacristinamarquez/2024/11/08/three-sharks-three-fates-the-genetic-divide-of-great-whites/

https://www.sciencedirect.com/science/article/pii/S0960982224008601?dgcid=coauthor

https://www.britannica.com/science/ocean-basin

https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Map%3A_Raven_Biology_12th_Edition/22%3A_The_Origin_of_Species/22.01%3A_The_Nature_of_Species_and_the_Biological_Species_Concept/22.1.02%3A_Formation_of_New_Species/22.1.2.2%3A_Reproductive_Isolation#:~:text=In%20some%20cases%2C%20populations%20of,now%20reproductively%20and%20genetically%20independent.

Why is shark DNA so fascinating?

 

Marine scientists all over the world are using new, innovative technology to better understand sharks genetic information that can help us better understand their biology, movement, and evolution. DNA in sharks is rapidly being observed to also show migrating patterns, unique adaptations, and even susceptibility to certain diseases within a species. Marine geneticists have found that the shortfin mako has a genome almost 1.6 times bigger than our own. Other species, such as the great white have also shown a very stable genome, explaining that very little genetic mutations occur. Having a more stable genome leads to being less susceptible to diseases caused by mutations such as cancer. Sharks genomes are also being observed because of their incredible wound-healing ability. Although we have similar genome, our ability to heal isn’t quite as fast, or efficient. Through more studies, we can utilize this information to truly understand them and protect them.

    Sharks have always been so incredibly fascinating to me. Their species, adaptations, movement patterns, etc. Because of external stressors increasing, such as global warming and overfishing, it is so important we study them to learn how we can conserve and understand what makes them up. Diving into their genome could help innovate the idea of genetics itself, and how we could possibly implement that development into human research as well.

Link to article: https://saveourseas.com/worldofsharks/podcast/what-can-we-learn-from-a-sharks-dna#