Daphnia

Around 600 million years ago, marine invertebrates emerged as Earth’s first multicellular organisms. Today, Gracie Scheve is scheming to make a career out of researching their extraordinary life cycles. Her interest in invertebrate evolution and development has not come out of the blue though. Gracie’s family would drive down from their home in Cincinnati, Ohio to Florida every summer for vacation when she was little. There, she would load buckets onto her paddle board, paddle out to sea, and collect countless jellyfish. Back on shore, she would spend hours marveling at her catch. Now, years later, Gracie has carved out her niche in invertebrate biology as a senior researcher in the Rogalski lab at Bowdoin College. With Professor Rogalski, she investigates reproductive strategies of Daphnia, or the common water flea.

In late Spring, Gracie brought me along to her study lake. While she collected water samples, Gracie explained that Daphnia are cyclical parthenogens. In simple terms, they can reproduce both sexually and asexually. Typically, their wild population is exclusively female. This all-female population reproduces asexually into the next generation of clonal daughters with every reproduction cycle. In Gracie’s words “Daphnia are girl bosses”. However, things change when they encounter stress. For example, disease can trigger Daphnia to produce males with which the females will sexually reproduce. This, in turn, results in more genetic diversity, which increases the population’s stress tolerance and survival probability. Through her research, Gracie hopes to gain more clarity on what stresses alter reproductive behavior, and by what mechanism.

Over the summer of 2024, Gracie observed an unexpected pattern in the field; the only stress factor that seemed related to an uptick in sexual reproduction was a novel fungal parasite. Though this might mean Gracie and Professor Rogalski will get to name a new genus of fungus, for now, it is leading to more questions than answers. For example, how does the fungus affect Daphnia? And is it truly inducing sexual reproduction, or was Gracie’s observation merely coincidental? Gracie is currently experimenting with this fungus in the lab. She admitted that she might not find the answers before the end of her senior year. However, she is excited about the novelty of her research.

Along with asking new questions comes a level of uncertainty that makes Gracie’s research unpredictable. It means that over the past months, Gracie has experienced many unexpected turns, like when all Daphnia had disappeared in mid-June. She recognizes these surprises are a natural part of research and that it is a good thing she is learning how to handle them now – especially because she hopes to take her next step into an evolutionary biology PhD program. Her undergraduate research experiences have taught her not only to be flexible, but also that research requires an underappreciated range of soft skills. Whereas quantitative skills and book smarts seem to prevail, Gracie shared that having an open mind, being persistent, and being patient with oneself are some of the most important qualities of a researcher. Wherever Gracie will go next, she will take these lessons with her.