Evolution Underwater

Flávia Petean (Evolutionary Biology Postdoc at National University of General San Martin || Argentina)

“I grew up saying I want to study sharks. I don’t know when it started, it kind of just happened, and so I pursued it! I studied the evolution of so-called ‘cookie-cutter sharks’. They are small sharks that have very large teeth and bite tuna, whales, or dolphins — like a parasite, they don’t kill the other animal, they just eat a piece of its flesh, like they’re eating a cookie. Most of my samples come from museums, which makes them much easier to dissect because they are right there. No need to go to the ocean, rent a boat, pay a fisherman, catch the shark. After a dissection, we don’t throw away all the pieces, we preserve them for future research of other teams. There were thought to be three species of cookie-cutter sharks. I studied as many specimens as I could from all over the world, so that I could say, okay, there are not three species, actually there are just two!

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As a next project, I wanted to learn new tools and got interested in studying stingray genetics. As part of my work I went to fish markets and talked to fishermen, asking to remove just a tiny piece of tissue from the stingrays they caught. Then I brought the sample tissues back to my lab to decode their DNA. I was interested to delimit the species, learn where they live, and look into their past to identify what could have diversified the species, such as the closure of the Panama Canal. Through my work combining tools of genetics as well as morphologic and ecological niche modeling, I identified a new species that is endemic to Brazil. I gave the new species a feminine name, Hypanus berthalutzae. Bertha Lutz is a Brazilian biologist, the first woman to get a job in a public institution in Brazil and advocating for female rights to vote in Brazil. The paper announcing the new species came out last year on the same day as Bertha Lutz’s birthday. Such a coincidence!”