NATURALIST SELECTIONS IS AN INTERVIEW SERIES PRODUCED BY THE AMERICAN SOCIETY OF NATURALISTS GRADUATE COUNCIL. WE SHOWCASE GRADUATE STUDENT AND POSTDOC AUTHORED WORK IN THE AMERICAN NATURALIST, A PREMIER PEER-REVIEWED JOURNAL FOR ECOLOGY, EVOLUTION, AND ANIMAL BEHAVIOR RESEARCH. CATCH UP ON EXCITING NEW PAPERS YOU MAY HAVE MISSED FROM THE JOURNAL, AND MEET SOME TRULY BRILLIANT EARLY CAREER NATURALISTS!

*Featured image photo credit: Rebecca Robinson

In this episode, Zach Wood talks with us about his new paper Wood et al. 2022: ‘Drivers and Cascading Ecological Consequences of Gambusia affinis Trait Variation.’ We dive into the weird world of human-created pond ecosystems and how these ponds afford a unique opportunity to study rapid contemporary eco-evolutionary dynamics in predator-prey interactions. We also discuss the challenges of dissecting all the possible causes of trait variation in the wild and explore other ecological and genetic contexts that might affect varying patterns of anti-predator evolution among mosquitofish ponds. Listen to our conversation and then read Zach’s full paper here: https://www.journals.uchicago.edu/doi/10.1086/717866.

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Craving more context? Email Zach at zachary.t.wood@maine.edu!

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Credits

Featured Guest: Dr. Zach Wood, University of Maine

Host, Editor, Producer: Sarah McPeek, University of Virginia, US

Original Music: Daniel Nondorf, University of Virginia, US

Transcript:

You’re listening to Naturalist Selections, an interview series featuring graduate student and postdoc-authored work in The American Naturalist, produced by the American Society of Naturalists Graduate Council. I’m Sarah McPeek and today I’m talking with postdoc first-author Zach Wood about his new paper, “Drivers and cascading ecological consequences of Gambusia affinis trait variation.” Zach completed this project during his PhD work with Dr. Michael Kinnison at the University of Maine. Zach’s work with Dr. Kinnison and collaborators tackles the causes and consequences of predator-mediated trait variation in introduced mosquitofish. They traveled across the western United States collecting mosquitofish from ponds with voracious bass predators, ponds with slightly less voracious bluegill predators, and ponds with no predators. Then they raised these fish either in the presence or absence of bass predator cues to tease out the predator-mediated plastic, genetic, and evolved plastic components of morphological and behavioral trait variation in their fish populations. They then introduced these mosquitofish to pond mesocosms containing a wide diversity of invertebrate and algal prey to further measure how predator-mediated trait variation and fish population density affect the composition of mosquitofish’s own prey community. Most interestingly, they find that mosquitofish from different source ponds exhibit non-congruent plastic and evolutionary responses to the same predators. Fish from some populations exhibited strong behavioral responses such as higher flightiness in response to predator cues or lower feeding rates, while fish from other populations that also have predators exhibit strong shifts in morphology such as upturned head angles or longer tail lengths. In our conversation, Zach and I plunge deep into the complexity of these eco-evolutionary patterns and muse over other contexts that may matter for anti-predator evolution.

Sarah

I’m really curious what these mosquitofish ponds look like out in California and why you think that mosquito fish are a really good model for studying these ecological cascading effects that you’re interested in?

Zach

Yeah, that’s a good question. Mosquitofish are perceived as this panacea for vector control. So meaning if you have an area that has mosquito borne diseases, mosquitofish by the name are one of the first things that are thought of as a remediation agent. So you dump in these fish that I mean, they must be good at eating mosquito larvae. They’re called mosquitofish, and that’s a really popular practice in big parts of the United States. And so these mosquitofish are relative newcomers. Some of these populations have only existed for maybe a decade, and a lot of the other fish in these ponds are also newcomers. So there are bass and bluegill and other fish that are not native to these ponds and have also been introduced. So in terms of the community, it’s really what we’d call ecologically a novel community. It’s a lot of strange bedfellows. And so this creates a lot of really intense interactions because mosquitofish are voracious consumers of just about anything invertebrate. So whether it’s benthic chironomid larvae or zooplankton, mosquitofish are just sort of like a vacuum that takes them down. And the predators of mosquitofish like bass and bluegill also tend to be just as aggressive, which has given them their invasive label. So they’re very strange bonds in that regard, and that basically everything above the invertebrate level is often nonnative. So some of these are barely bigger than a pool, like a swimming pool, and others are what you’d think of as like, okay, that’s a little Lake. And they really range from kind of marshy, very green coastal ponds to some ultra-clear desert springs. So I’m thinking one of the ponds that we work in in this paper in Eastern California desert is like, yes, the size of my living room, Crystal clear water.

Sarah

Oh, wow.

Zach

Yeah. Oh, there’s golf courses. Some of these are golf course ponds. So they’re like, as green as you can imagine. So ecologically, they vary quite a lot, too. And I’m sure that has something to do with some of the results that we’ve seen that we’ll talk about later.

Sarah

Sure. Yeah. So when you are selecting your ponds to pull fish from in these experiments, were you trying to maximize that ecological variation or were you trying to lump ponds into three different categories. So is that something that you were focusing on when you were designing the experiment?

Zach

Yeah, we were mostly limited by the different predator regimes. So trying to find ponds that just had bluegill but not bass, ponds that just had bass but not bluegill, and ponds that had neither. And of course, then there’s the more logistical concerns, like access, just being able to get in there and not having to fight a housing association or something to get into the pond in someone’s backyard. That can be