The Visual Systems of Butterflies
Erica Westerman, welcome.
Erica Westerman: Thank you.
HY: So you’re professor of biological sciences here at the U of A. Would you also consider yourself to be an entomologist?
EW: I would! Because I do study butterflies, but I primarily consider myself an integrative animal behaviorist because we take multiple techniques to understand how behaviors work. So, for example, we go out in the field – the prairies of northwestern Arkansas. We conduct research in a greenhouse. We use genetics and we use developmental tools to understand diversity and behavior.
HY: OK. So let me ask you this. Did your interest in this evolve slowly over time or was there an experiment or experience that pushed you into this?
EW: When thinking about animals, I’ve always been fascinated by animals from a very young age and understanding, like, how cats move, how dolphins communicate with each other, how waved albatross, which are these gigantic birds, form lifelong pair bonds. But when it comes to butterflies, I use butterflies to understand behavior because butterflies are — I just really think the best group of animals to work with. They’re incredibly speciose, so many, many, many species. The Lepidoptera, which is butterflies and moths, are second only to beetles in terms of number of species. And when I started my PhD I got the opportunity to kind of accidentally start working with butterflies and just completely fell in love with the system.
HY: OK. And that became your model organism. OK, so is there first, are there any other insects that you’ve studied as closely as you studied butterflies or is it primarily the butterfly?
EW: It’s primarily butterflies. I do a little bit with moths, so I dabble outside of the butterflies, but it’s mostly butterflies.
HY: I think probably for most people, butterflies and moths are closely related. Is that true or is that — what is the difference?
EW: They are closely related but moths you usually see at night. Now there are a few day flying moths for anybody who’s seen the hummingbird moths. There are two species of day-flying moths here in northwestern Arkansas. The one that mimics a hummingbird, so they’re quite large and they look like hummingbirds but you’ll notice if you look at them like, “that’s not a bird tail.” It’s actually like a large moth. And then we have moths that mimic bees. But most moths fly at night. They have slightly hairier bodies. They have bigger antennae, and they’re more focused on olfactory cues than butterflies. Butterflies, being day-flying, have more slender bodies, longer antennae, bigger eyes and, like, thinner antennae, and they’re much more focused on visual signals.
HY: Well, which brings me to my next question. For your CAREER award, you’ll be studying the visual systems of butterflies. Can you tell us a little bit about the focus of this project?
EW: So one of the things that we are really interested in is how the developmental environment interacts with the genome to give you the diversity of adults that we see in butterflies, but also in many different species, including humans. And a way to think about this is often when we’re taught about how a genome and an adult phenotype of what we see when we look at another organism interacts we usually think of this as a blueprint. So the analogy that’s often used is you have a blueprint for a house, you’re going to take that blueprint, you’re going to build a house.
HY: And in this case, the blueprint is the genome?
EW: The blueprint would be the genome. It gives the instructions for building the animal, but it’s actually a little bit more interesting than that. It’s as if you have this blueprint for a house, but if you build that blueprint in northwestern Arkansas, you’re going to get a house with a nice walkout basement. If you build that blueprint in New Hampshire or Maine, you’re going to get a house that has a really steep roof that allows the snow to fall down. If you take that same blueprint and build that blueprint in Hawaii, you’re going to get a wraparound porch or lanai. So, the genome is getting information from the environment that they’re in while the animal is developing to produce different adult phenotypes that are better fit for their environment. So, we are looking at that in the context of the light environment. How does the light environment that a caterpillar experiences shape the sensory system of the adult butterfly? So, if we think about our prairie environment here in northwestern Arkansas, at the beginning of the season, the grass is green, it’s quite lush, but it’s also short. If you think about our environment in August, the grass is usually drier, but it’s much taller, so the color is different and the environment in which the caterpillar is growing up is different. And we want to see if that influences the visual system of our pollinators and the decisions that our pollinators make.
HY: What’s driving this interest? What are the larger implications?
EW: So the larger implications are from both an urbanization and a climate change perspective. So butterflies are one of many groups of pollinators that we have and pollinators are critically important for all of our fruit crops and a variety of other crops, as well. And pollinators pick which flowers to go to, partially based on odor and also partially based on visual cues. So they’re using the visual simulation of these flowers to pick where they’re going to go. And who they’re going to pollinate. And if the visual system is influenced by their developmental environment, we need to know how the variation in the developmental environment, due to increased urbanization, which may change the colorscape and the height of the foliage, the colors of the flowers, the presence of flowers, and the different amount of shade environment that these caterpillars are going to experience. And also climate change may change the height and the amount of drought that we experience. All of which is going to shift the light environment and temperature environment and consequently, potentially, the visual abilities and decisions of all of our pollinators.
HY: And some of those decisions will include mates?
EW: It should include mate choice, so we are particularly interested in both mate choice and flower selection because I think those are two of the most important and most interesting decisions that pollinators make. Who do they pick to mate with and what flowers are they going to go to to find food.
HY: And what flowers do butterflies tend to pollinate around here – or flowers and fruits?
EW: So we have a really diverse butterfly population. We have butterfly pollinators that are visiting the most, if not all, of the flowers in our ecosystem. And there are some flowers that are not dependent on pollinators, but most flowers are. And some of the research that I have done in collaboration with the Botanical Gardens, in a big community ecology project that’s been a wonderful opportunity to interact with a lot of people here in northwestern Arkansas, has shown us that different colors of butterflies – so butterflies of different species – are visiting different flowers. So, if you have a diverse set of flowers in your garden you’re going to bring in a diverse set of pollinators. Some of the crops that are pollinated by Lepidoptera include apples and blueberries and peaches. There are some peaches that self[-fertilize], but most of our fruit crops are pollinated by insect pollinators, and many of those include Lepidoptera.
HY: I’m glad you mentioned the Botanical Garden of the Ozarks because they’ve been recruiting volunteers to watch butterflies and report what they see. So, can you talk a little bit about the project and how people who may be Interested can help out?
EW: Absolutely, I’m so glad you brought this up. This is a project that I’ve been working on with the Botanical Gardens of the Ozarks since I got here. So, we started in spring 2017 and what we are doing is asking community members – so anybody who visits the garden, this is an activity that’s good for enthusiasts of all ages. We have very young participants. We have participants who are more advanced in their life experiences. And we ask participants who go to the garden to look around the garden, look at the butterflies. For any butterfly that you see, record the color of the butterfly. What is the butterfly is doing. Are they flying? Are they feeding? Are they sitting on a plant? If they’re on a plant, what color of plant are they on? And we use this data to get an understanding of seasonal variation in butterfly activity, color variation and color preferences in different species of butterflies. And we also record size with this data, so we can actually usually get a pretty good sense of what butterfly species we’re looking at when we look at the colors that are circled and the sizes that are circled of the butterflies. So we have a pretty good sense of what butterflies the community members are recording, and we use this to get data on thousands of butterflies. So many more individuals than we would ever be able to collect if it was just my research group.
HY: Yeah, it’s crowdsourcing. You said the garden. But this is not limited to the Botanical Garden. This could be anybody, anywhere, where they’re out seeing butterflies.
EW: It could be anybody, anywhere. We do have a link on the Botanical Gardens website that is for people recording in their own gardens or at home. So if you aren’t in the botanical gardens, but you still want to participate, you absolutely can. There’s a place to include your latitude and longitude so that when my research group is analyzing the data, we know where that data came from.
HY: And what kind of response have you had on this so far?
EW: Over the first four years — we’ve analyzed the first four years of data, we’ve gotten at least 1,000 participants between the Botanical Gardens of the Ozarks, as well as my animal behavior class participates. And my principles of zoology class participates every year.
HY: Your animal behavior class. Just quickly, let’s plug that because this sounds kind of fun. Could you describe what goes on in that class?
EW: Sure! My upper-level class that I teach is this animal behavior class and in animal behavior the students learn how to conduct animal behavior research. So they learn the principles of animal behavior, but they also learn how to actually go out and conduct animal behavior research. So we spend a lot of time learning how to build ethograms, which are how we record behaviors. So how you define a behavior and how you teach other people in your group to have, like, the same definition of a behavior, because that’s not trivial. Making sure that you all agree on what a tail flick is or what a chirp is versus a song, if you’re thinking about different bird calls. And then the students go out and they conduct group projects and they learn how to write a scientific paper. They learn how to write a method section. They learn how to do statistical analyses. And then they present the project to their class. So they basically take a project from start to finish as a group in a very short period of time. And everybody walks out of the class knowing a little bit about our statistics programming as well as how to conduct animal behavior research.
HY: That sounds like a lot of fun. Eric Westerman, thank you for coming in today.
EW: Thank you. Been a pleasure.
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