Researching rapid evolution in fruit flies

Seth Rudman, an assistant professor in WSU Vancouver’s School of Biological Sciences, has research interests centering around rapid evolution, rapid adaption in response to environmental stressors, and whole genome evolutionary change within a changing environment. Rudman received his Ph.D. in evolutionary ecology at the University of British Columbia, studying the interaction between ecology and rapid evolution in stickleback fish. Rudman’s postdoctoral work at the University of Pennsylvania expanded on this research, using bioinformatics to gain a better understanding of genomic and microbiome evolution.

Seth Rudman working in his lab at WSU Vancouver

Rudman’s lab at WSU Vancouver houses fruit flies, or Drosophila. Originally, he had decided never to work with fruit flies. At the University of Rochester, where Rudman received his bachelor’s degree in evolutionary biology, many of the professors worked with fruit flies. Rudman found this research “fundamentally uninteresting,” he said. Instead, he turned to field herpetology, working for the national park system in South Africa.

But Rudman’s own research interests led him to change his mind about fruit fly research. “Slowly but surely, I got more interested in the questions about what influences populations and their ability to survive in challenging environments. And the more interested I got in those questions, the more that I saw systems where I’d be able to answer those questions—until one day, I woke up and found myself running a Drosophila laboratory here at WSU Vancouver,” said Rudman.

He’s become a convert. Fruit flies are plentiful and easy to care for. “Drosophila is a fantastic model system,” he said. “I don’t know of any animal model system that’s easier to take care of. And it’s easy to do large experiments with because they’re very, very happy with minimal effort.” And because fruit fly genetics have been studied for more than 100 years, their genomes are easy to sequence and analyze. Moreover, fruit flies can evolve rapidly, often within a single season.

Seth Rudman at his fruit fly facility at WSU Vancouver

Rudman recently received a five-year $1.89 million Maximizing Investigators’ Research Award (MIRA) from the National Institutes of Health to study rapid evolution in fruit flies. By using natural environmental changes to drive evolution, Rudman investigates fruit fly evolution “in the wild.” The reason for this research, said Rudman, is to “understand how variation in the genome influences evolutionary outcomes in more realistic settings. And that can help us predict things like how evolution is actually going to occur in pandemic settings or in tumor/cancer settings or in a disease vector setting.”

To create these natural conditions, Rudman planted an orchard near the campus sports annex and assembled large, tent-like structures over the trees. The fruit fly “tents” combine the convenience of the lab with a realistic outdoor setting, allowing selection pressures like wind, rain and heat to act on the fruit fly populations. As an added selection pressure, Rudman and his team treated their fruit fly populations with the organic pesticide Spinosad from June to October.

Catherine Irene Clare, Seth Rudman and Rene Sahba Shahmohamadloo at the outdoor fruit fly enclosure at WSU Vancouver

Their next step is to analyze the genomes of the fruit flies they sampled throughout this time, but Rudman already expects to learn a lot. For example, early in the experiment, the insecticide nearly killed off the fruit fly populations. “We were nervous about this, and we thought we maybe would stop doing the treatment, but instead we pushed through and what ended up happening was the populations rebounded,” Rudman said. This phenomenon, called evolutionary rescue, has ecological implications for endangered species: “It’s a process that we’re really interested in studying because it’s a potentially important one for the maintenance and preservation of biodiversity,” said Rudman, “I am fascinated with the idea and the notion that evolution can rescue populations from extinction.”

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