Orange is the new aphrodisiac—for guppies

It turns out colour isn’t just a fashion statement for guppies. According to a new University of British Columbia study, the more orange the male guppy, the more virile it is.

The research, published in Nature Ecology and Evolution shines light on an enduring evolutionary mystery—why male guppies have such vibrant and varied colours and patterns.

Zoologists Drs. Wouter van der Bijl and Judith Mank used deep learning, genetic studies and bred three generations of increasingly orange guppies to investigate the mystery.

They found the more colourful males were up to two times more sexually active, performing for females at a greater rate and for longer periods of time. They also attempted to sneakily copulate more often.

It’s known that female guppies prefer orange, and unusual, patterns in their male partners, but the team found that the colour 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.

Orange you glad to see me, baby?

The researchers found the guppy colour genes, and the locations they appeared in, were tied to multiple chromosomes, creating a vast architecture of genetic possibilities. Seven orange and eight black colour types were identified overall, allowing for, potentially, up to 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 Dr. van der Bijl. “We often look at extreme examples to understand where genetic variation comes from and how it’s maintained.”