Biologists at the University of California at Irvine have discovered female and male butterflies of a certain species see differently due to sex-related evolutionary traits.

The study, which was published in the academic journal Molecular Biology and Evolution, marks a significant contribution to evolutionary biology because it presents new insight into selective environmental factors that drive the evolution of these butterflies' eyes.

Adriana D.Briscoe, a UC professor of ecology and evolutionary biology at the Ayala College of Biological Sciences, led a team of researchers through the study, analyzing the structural components of the physical eyes and the genes that control color-detecting photoreceptors.

The study revealed that the species in question, dubbed Heliconius erato, carries unique visual photoreceptors that are sexually determined, meaning that the eyes of the female are different from the eyes of the male.The females have two kinds of the ultraviolet opsin gene: UVRh1 and UVRh2.Males do not have UVRh1.

The groundbreaking findings shocked the research team.Heliconius erato is the first (and so far only) animal in the world known to have sex-determined eyes.

"We are only now beginning to appreciate that male and female Heliconius see the world through different eyes," Briscoe says. "Pollinator preference can have a huge impact on the evolution of flower coloration, just by virtue of which flower gets visited.Flowers may change their colors to match what butterflies can see; and sex differences add another layer to the story of these interactions."