Meet the reproductive biologist studying cavefish

The spark for Dr. Kaitlyn Webster’s scientific career was a question. She remembers being a young teen in science class, staring down at her sparkly, pink, glow-in-the-dark nail-polish and wondering what made it glow in the dark. She asked her teacher, expecting either a jargon-filled, scientific answer or a simple “I don’t know.” Instead, her teacher smiled and responded, “let’s go find out.”

Today, she’s a postdoctoral researcher at the Tabin Lab at Harvard Medical School, but Webster’s scientific career has been fueled by that urge to go find out. Whether it’s why nail polish glows or her current research on sperm and egg recognition in cavefish, there’s a universe full of unknowns that are waiting for curious minds to inquire. Webster’s work could change our understanding of how new species are created, and even have long-term impacts to fertility treatments.

Webster is what’s known as a basic scientist, someone who dares to ask fundamental questions knowing the path to the answers might be long and the path to society appreciating these findings might be even longer. “Basic research is filling up a library with all of this knowledge. And someday, people will call on that knowledge and synthesize it for a project. But there are going to be no more books in the library if we don’t keep toiling away at our one weird question,” says Webster. The ocean of unknown between why something happens and why it matters might seem murky, but it’s vital to expanding our understanding of the world — and fertility, in Webster’s case.

Webster is one of five 2025 awardees of the L’Oréal USA For Women in Science Program which will give her the ability to further her research on the cavefish and continue to contribute to the library of knowledge production around fertility. Basic science research can get overlooked because its results may feel less tangible, but it is the pipeline that feeds scientific advancements. This award honors and supports that potential for impact in Webster’s work, both in her current research and her career as a whole.

The “weird” question that Webster is currently asking begins with cavefish. The Mexican tetra fish is a unique example of rapid evolution, with two morphotypes (or varieties) of the same species that have very different characteristics adapted to the two environments they live in — the river or the depths of a cave. (It should be noted that there are actually 33 cave populations of Mexican tetra, and they arose at different times. Some cave populations emerged as rapidly as 25,000 years ago, but other populations have been around for hundreds of thousands to millennia.) While the surface fish look like a typical fish, their cave counterparts have no eyes or pigment.

And yet somehow, these fish have the ability to breed with each other, or hybridize. The sperm of one fish morph can successfully fertilize the egg of another, or vice versa, and these hybrids are fertile offspring that can reproduce — an anomaly in evolutionary biology. Webster’s research into how and why these fish hybridize unlocks a much bigger question: how do sperm of all species, including humans, know where and how to successfully fertilize an egg?

This question, and all of the follow-up questions it sparks, is fundamental to understanding the origins of life and could eventually transform how medicine addresses human fertility challenges. “We take for granted what science knows or what we’ve figured out. And you would think that sperm and egg interactions were at the top of the list,” Webster says. But this, she confirms, is largely unknown today.

The journey to become a scientist, in the official sense, is long: from early scientific interest in middle school and high school, to lab work in undergraduate, to years-long PhD research, to finding a postdoctoral position, to eventually becoming a principal investigator of your own lab. Along this path, there are barriers that can disproportionally affect the retention of female scientists in particular, for instance, statistically smaller research grants or toxic lab environments. But mentorship can make a difference.

For Webster, serving as a mentor with Science Club for Girls mirrors crucial mentorship she credits with allowing herself to imagine a future in science. Science Club for Girls serves girls and gender expansive youth in the Boston area by connecting students K-12 to mentors from their own neighborhoods. As students grow in the program, they’re able to become junior mentors, in turn, creating a longitudinal network of mentorship throughout their scientific journey.

Understanding that a future exists for them in science is key to keeping women and girls in the field — and creating a pipeline of more ground-breaking researchers like Webster going forward. Along every stage of a scientist’s career, from elementary school to principal investigator, asking “weird” questions about things like glow-in-the-dark nail polish could very well morph into fundamental questions about the origins of life.

“For women in STEM, many of us have found ourselves as the only woman in a room, the only woman in a lab,” Webster said. “It’s just easier when another person who came before you learned some stuff the hard way or figured out things that took a long time, and they can pass on that knowledge and those experiences and those traits to you and increase your chances of success.”