How the bumble bee got its stripes

APRIL 29, 2019

by Pennsylvania State University

Researchers have discovered a gene that drives color differences within a species of bumble bees. This discovery helps to explain the highly diverse color patterns among bumble bee species as well as how mimicry—individuals in an area adopting similar color patterns—evolves. A study describing the gene, which occurs in a highly conserved region of the genome that provides blueprints for segmentation, was led by researchers at Penn State and appears April 29, 2019, in the journal Proceedings of the National Academy of Sciences.

"There is exceptional diversity in coloration of bumble bees," said Heather Hines, assistant professor of biology and of entomology at Penn State and principal investigator of the study. "Of the roughly 250 species of bumble bees, there are over 400 different color patterns that basically mix and match the same few colors over the different segments of a bee's body."

The most common bumble bee color patterns feature red around a bee's tail, thought to advertise its dangerous sting. In spite of the great diversity available, color patterns tend to converge toward similarity within a particular geographic region because they serve as an important and effective warning signal. This is an example of Müllerian mimicry, where similar, often vibrant, color patterns are used among multiple species to warn predators of a dangerous feature like toxicity or sharp spines.

"Müllerian mimicry has served as an example of evolution since the days of Darwin," said Hines. "Studying these mimicry systems—similar color patterns in many different species—allows us to see how natural traits evolve. It can also tell us about how traits are encoded in the genome: is there only one way to make a trait, or do different species arrive at similar traits through different genetic pathways?"

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