BEACON Researchers at Work: A foreigner’s forays into experimental evolution

This week’s BEACON Researchers at Work blog post is by MSU graduate student Carina Baskett.

In my native habitat, looking for caterpillars on pokeweed plants.

In my native habitat, looking for caterpillars on pokeweed plants.

When I spent a semester of college in Buenos Aires, Argentina, we American students were endlessly fascinated by cultural differences between the US and Argentina. As we awkwardly learned to navigate the warm Argentine culture (e.g., it is customary to kiss everyone in the room upon arriving a party), we found it symbolic that there is no Spanish translation to describe someone as “awkward.” The rules of the road were also notably different, put best by an Argentine who had recently visited the US. “It’s so weird!” she told her friends. “People actually use turn signals when they’re changing lanes!”

I found myself in a foreign land again last winter and spring, when I was working on an experimental evolution project with bacteria and viruses at a lab bench. You see, I am a plant biologist, and most of my data comes from fieldwork. I am happiest when sitting in front of a flower and watching for pollinators to alight, or when turning over a couple thousand leaves to find a few caterpillars. Plants fascinate me; although lacking brains or the ability to move, they have adapted creative ways to have sex, disperse their seeds, defend themselves from hungry hungry caterpillars, and survive winter.

So how did this plant geek end up working on an experimental evolution project? I asked myself that question many times, especially when things weren’t working! The short answer is that even though plants are awesome, they are too big and grow too slowly to directly address the question I was burning to answer.

I talked in detail about that question here: why are the tropics so diverse? Although I do get to work with plants in nature for part of my research, another part of it is only possible by conducting an evolution experiment with bacteria. I will save the details of our study for a future post, when I can talk about results. Right now, it’s still very much a work in progress.

Designing the project involved many hours of brainstorming over breakfast and beer (usually not at the same time) with my collaborators, Alita Burmeister, Luis Zaman, and Justin Meyer, not to mention sage advice from Ben Kerr and my advisor, Doug Schemske. We came up with some ideas about how to recapitulate some essential differences between tropical and temperate environments in the lab, and obtained BEACON funding to study how those different environments would affect evolution of bacterial diversity.

Alita and I worked together last winter to get some preliminary data for her research while I learned the ropes (the flasks?) of microbiology research. That was when the language barrier really hit me! Don’t tell my collaborators, but I can never remember which important genes and proteins are which in our system, despite their patient, repeated explanations. Somehow the function of “ompF” just doesn’t stick in my head as well as the image of “Carolina horsenettle.”

Despite my poor memory for these details, I learned a ton from working with Alita in preparation for the next step. In early March, on a grey day that I think was the first above freezing in at least a month, I flew to sunny San Diego to spend three months conducting our carefully designed experiment in Justin’s brand-new lab at UCSD, where Luis was setting up essential new equipment for the project.

That equipment was a device called a “morbidostat,” which would allow us to use antibiotics to control bacterial death rates, even as they evolved resistance. It sounds great, but it’s a new device, whose technical issues are still being worked out—by us! It didn’t take long before we realized that a lot of our carefully designed ideas and plans weren’t going to work exactly as we’d hoped. This was a familiar realization from my fieldwork experience, but I wasn’t expecting to encounter it in the lab. I thought we could control everything perfectly in the lab! I thought we could get beautiful data by starting a bacterial culture, pressing some buttons and typing programs into a computer!

The flask on the left is cloudy with a large E. coli population, despite the presence of a virus. The population in the flask on the right has crashed, likely because the virus has evolved a new way of invading the bacterial cells. How cool is that??

The flask on the left is cloudy with a large E. coli population, despite the presence of a virus. The population in the flask on the right has crashed, likely because the virus has evolved a new way of invading the bacterial cells. How cool is that??

Turns out that biology, chemistry, and luck—nature, in other words—can wreak havoc on the best-laid plans of microbiologists, not just field ecologists. For instance, I spend several weeks of my limited time there battling a mysterious, recurring precipitation in the media that we were using to grow our bacteria. Eventually I found that we had been adjusting the pH higher than we should have been, an issue that was exacerbated to the point of precipitation because the pH meter had become slightly off-kilter…possibly my fault, for not storing it properly over one night.

I know this kind of setback is completely normal in all aspects of science, but in those frustrating moments I wondered whether I preferred the headaches from fieldwork to those from the lab. It’s hard to decide though, because the rewards from experimental evolution are great. I still have photos of flasks and plates on my phone from the experiment that Alita and I worked on almost a year ago, and I still pull them out to show people how amazing it is to be able to see evolution happening from one day to the next. For example, we would come into the lab sometimes and see that a flask that should have been cloudy with bacteria was clear, an indication that overnight its virus had evolved a new way to bypass bacterial resistance. Evolution in action is really exciting! Even this plant geek can freely admit that.

So will I pursue dual-citizenship in the worlds of plant field ecology and microbial experimental evolution? I’m not quite sure yet. When (not if!) we eventually finish this project, I’ll decide whether I enjoy the work enough to look for a post-doc in an experimental evolution lab. If so, I hope that someday working in the lab won’t feel so awkward.

A virus entering a bacterial cell, or a scarlet macaw flying out of a tree? Hmmm...

A virus entering a bacterial cell, or a scarlet macaw flying out of a tree? Hmmm…

For more information about Carina’s work, you can contact her at baskettc at msu dot edu.

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