Evolution of mate preference in polymorphic butterflies. These white Heliconius cydno alithea butterflies are mating on a passionflower vine, but the male had a choice between white and yellow-winged females. Nicholas VanKuren, Nathan Buerkle, and their co-authors dive into the genetics and neurobiology of mate choice behavior and find surprising variation in the genome and the eye that correlates with male preference. (Credit: Wei Lu CC-BY 4.0, https://creativecommons.org/licenses/by/4.0/)
In a nutshell
- Butterflies choose mates based on vision, not scent or chance. Heliconius cydno butterflies are biologically wired to prefer mates with matching wing colors, and this preference is driven by their visual system.
- Neural wiring in the eyes influences mate selection. Differences in how ultraviolet (UV) and long-wavelength (green/red) photoreceptors interact determine which wing colors butterflies find attractive, making mate choice a hardwired trait rather than a learned behavior.
- When butterflies develop different visual-based mating preferences, they stop interbreeding with others, potentially leading to speciation over time.
CHICAGO — When it comes to finding a partner, looks matter, especially if you’re a butterfly. For certain species of colorful tropical butterflies, the connection between vision and mate choice goes deeper than scientists previously thought. A new study from the University of Chicago uncovers how differences in butterfly eyes influence their dating preferences, potentially playing a role in the evolution of new species.
Research published in PLOS Biology found a fascinating link between butterflies’ wing colors, the genes controlling those colors, and the brain circuitry determining which mates they find attractive. The study focused on Heliconius cydno butterflies, which have either yellow or white wings.
The Genetics of Butterfly Romance
Heliconius butterflies have long fascinated biologists due to their diverse wing patterns, which serve both as warning signals to predators and as identifiers for potential mates. Wing color and mate preference are controlled by genes located near each other on the same chromosome like neighbors on the same street.
For these butterflies, wing color isn’t just about looks; it directly affects who they’ll mate with. Yellow-winged males prefer yellow-winged females, while white-winged males show varying preferences. This seemingly simple distinction involves a mix of genetics, development, and vision.
Butterflies see color differently depending on how their eyes process light. Scientists found that in males who prefer yellow mates, about 70% of their UV-sensitive eye cells receive signals that tone down the impact of green and red light. In contrast, males who prefer white mates experience much less of this effect, only 17% of their UV cells get these signals. This difference in how their eyes filter color shapes what they find attractive, ultimately influencing their choice of mate.
Male butterflies find females with matching wing colors more attractive due to differences in how their brains process visual information, rather than simply because they are easier to see. When animals develop different mating preferences, they stop breeding with each other, a key step in the formation of new species.
Beyond Beauty: Evolution in Action
Two butterflies might see the same colors, but if their brains process the information differently, they might perceive those colors in entirely different ways. For butterflies in the wild, these differences in visual processing can mean the difference between recognizing a potential mate or ignoring them, ultimately shaping which genes get passed to future generations.
The Heliconius butterfly system offers an excellent model for studying how sensory perception, behavior, and genetics interact to influence evolutionary processes. The close connection between genes controlling wing color and those influencing mate preference provides insight into how these traits can evolve together, contributing to the rapid diversification of these butterflies.
A New View of Butterfly Attraction
For butterflies, attraction isn’t just subjective; it’s embedded in their brains through specific visual processing mechanisms. When butterflies in your garden choose particular flowers while ignoring others, remember that their choices reflect not just preference, but the intricate architecture of their eyes and brains.
Paper Summary
Methodology
Researchers combined three key approaches: genomic analysis of 113 male butterflies with known mating preferences; RNA sequencing of developing visual systems at various stages; and electrophysiological recordings from over 500 photoreceptors to measure their responses to different light wavelengths. This integrated approach allowed them to connect genetic variation with neural activity and mating behavior.
Results
The study revealed that genetic variants in the K locus and three other genomic regions—on chromosomes 7, 9, and 11—strongly correlate with mate preference. In butterflies preferring yellow mates, about 70% of UV-sensitive photoreceptors received inhibitory input from long-wavelength photoreceptors. White-preferring butterflies showed only 17% inhibition, while butterflies with no preference had intermediate levels. Seven genes near these genomic regions were differentially expressed in the visual systems of yellow versus white males.
Limitations
The study established correlations between genetic variation, neural physiology, and behavior but did not experimentally manipulate the candidate genes to confirm causality. It also used wing color as a proxy for mate preference in some analyses, which may not capture all behavioral nuances. Further research is needed to determine precisely how the identified genes influence neural wiring and behavior.
Discussion and Takeaways
The findings suggest that relatively simple modifications to peripheral sensory systems can drive significant behavioral changes without requiring extensive rewiring of complex brain circuits. This provides an efficient evolutionary pathway for rapid behavioral adaptation. The close genetic linkage between genes controlling wing color and mate preference helps explain how these traits co-evolve, facilitating rapid diversification. The peripheral nervous system appears particularly susceptible to evolutionary modification, offering insights into how sensory perception influences mate choice across species.
Funding and Disclosures
The research was supported by the National Science Foundation, a Dubner Fellowship, the University of Chicago Big Ideas Generator, a University of Chicago BSD Pilot Funds Award, and the National Institute of General Medical Sciences. The researchers declared no competing interests, and all butterfly collection and handling were conducted under appropriate permits.
Publication Information
The paper, titled “Genetic, developmental, and neural changes underlying the evolution of butterfly mate preference,” was published in PLOS Biology on March 11, 2025. The study was led by Nicholas W. VanKuren and Nathan P. Buerkle, with senior authors Stephanie E. Palmer and Marcus R. Kronforst from the University of Chicago.
