Arkansas study reveals butterflies' seasonal vision shift | Key insights

Understanding Seasonal Adaptations in Common Buckeye Butterflies

For the past few weeks in Arkansas, the weather has gradually shifted from warm summer to cool fall. This transition can be challenging for many animals, as adapting to changing seasons requires a variety of behavioral and physiological traits. One of the most noticeable ways animals respond to seasonal changes is through alterations in their coloration.

The common buckeye butterfly (Junonia coenia) has been a subject of scientific interest for over 100 years due to its distinct differences between summer and fall adults. Summer butterflies typically have light-colored wings, while fall adults display dark wings. Scientists believe that this darker coloration may help increase body temperature during cooler weather, similar to how some animals spend more time basking in the sun.

A team of researchers from the University of Arkansas, in collaboration with Cornell University, aimed to explore whether these seasonal changes in wing color are linked to genetic changes in the butterflies' visual systems. Their goal was to determine if seasonal shifts in wing color are also accompanied by changes in behavior and color sensitivity, as color vision plays a crucial role in many butterfly behaviors.

Between 2018 and 2021, the research team captured and observed common buckeyes in Northwest Arkansas from May to November. They analyzed gene expression patterns in eye tissue from both dark fall butterflies and light summer butterflies. The study revealed that dark fall butterflies were more likely to bask in the sun compared to their lighter counterparts.

Although the researchers did not find evidence that the butterflies’ color sensitivity changes throughout the year, they confirmed that the expression of many genes related to vision and eye development varies seasonally. This suggests that common buckeyes may perceive their environment differently depending on when they develop as caterpillars.

The next step for the researchers is to identify which aspects of the developmental environment are responsible for these changes in the visual system. Since buckeye butterflies only live for eight to ten days as adults, they experience only one season during their lifetime.

Grace Hirzel, who led the study, emphasized the importance of working with wild populations to understand how animals respond to seasonal changes in natural settings. She noted that common buckeye butterflies interact with their environment differently depending on the time of year and may even see the world differently at different times.

Hirzel, who conducted most of the fieldwork as a Ph.D. student in biological sciences at the University of Arkansas, published her findings in the journal Functional Ecology. Erica Westerman, an associate professor of biological sciences at the U of A, served as the corresponding author on the paper.

Westerman highlighted the value of studying species that exhibit plasticity in other areas. “We knew they had plasticity in their wing pattern,” she said. “If we’re going to get plasticity out in nature in a sensory system, buckeye butterflies are a good species to use. This is us getting our foot in the door and really trying to answer that big question of ‘how does the development environment influence our sensory perception?’”

Other contributors to the paper included Keity J. Farfán-Pira, a postdoctoral fellow in biological sciences at the University of Arkansas, and Chance Powell, a Ph.D. candidate in the same department. From Cornell University, Noah K. Brady, a Ph.D. candidate at the time, and Robert D. Reed, a professor of ecology and evolutionary biology, also contributed to the study.