Guppies aren’t just flashy for fashion — new research shows that bright orange males are actually more virile.
Scientists at UBC used deep learning and multigenerational breeding to show that color isn’t just attractive to females, it’s genetically tied to brain development and sexual behavior. The more vibrant the guppy, the more likely he is to be active, persistent, and biologically fit.
Colorful Clues to Guppy Virility
Color isn’t just about looks for male guppies. A new study from the University of British Columbia reveals that the more orange a male guppy is, the more sexually active and biologically vigorous it tends to be.
Published in Nature Ecology & Evolution, the study explores a long-standing evolutionary question: why do male guppies display such bright and diverse color patterns?
Sexy Science: What Orange Really Means
To find answers, zoologists Dr. Wouter van der Bijl and Dr. Judith Mank combined deep learning analysis with genetic research, breeding three generations of guppies with increasingly vivid orange coloring. Their findings showed that the most colorful males were up to twice as sexually active. These guppies courted females more frequently and for longer periods, and were also more likely to make stealthy attempts to mate.
Genes Behind the Glow
It’s known that female guppies prefer orange, and unusual, patterns in their male partners, but the team found that the color diversity of guppies comes from the same cells that are responsible for forming the brain, suggesting a genetic link between how guppies look and how they behave.
“Previously, people thought perhaps males realized that if they were more orange, they were more sexy. With the genetic link, it may be that they’re healthier and fitter,” said Dr. Mank.
Endless Combinations, Evolutionary Implications
The researchers found the guppy color genes, and the locations they appeared in, were tied to multiple chromosomes, creating a vast architecture of genetic possibilities. Seven orange and eight black color types were identified overall, allowing for a potential 32,768 unique pattern combinations.
“Genetic variation is the raw material that evolution uses to produce resilient, adapted animals and plants, including for things like climate change or disease,” said van der Bijl. “We often look at extreme examples to understand where genetic variation comes from and how it’s maintained.”
Reference: “Deep learning reveals the complex genetic architecture of male guppy colouration” by Wouter van der Bijl, Jacelyn J. Shu, Versara S. Goberdhan, Linley M. Sherin, Changfu Jia, Maria Cortazar-Chinarro, Alberto Corral-Lopez and Judith E. Mank, 1 July 2025, Nature Ecology & Evolution.
DOI: 10.1038/s41559-025-02781-w
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