Insight Into Evolution That Has Six Legs

It’s a story of a boy and an insect.

The boy: Joseph Parker, now an assistant professor of biology and biological engineering at Caltech.

The insect: the rove beetle, which Parker was passionate about as a child and has since turned into a life’s work.

So far so good. He recently set up a new lab at Caltech to study the beetles, and in fall he reported in Biorxiv how a flexible abdomen and chemical-producing gland could be easily modified to enable some rove beetles to mimic ants and live in the colonies as social parasites.

It began when he was about 7, growing up in Swansea, in south Wales. “I used to keep all these different tropical insects in my room,” he said, “and I think I wanted to just live in a rain forest and collect insects.” But, he said, the one that really caught his attention was a small, unassuming local beetle that was quite common. They were everywhere.

Still, he said, “there was never anything that came close to these beetles for me, and the funny thing is, they’re so tiny, you know, they’re a few millimeters long. But as soon as you put them under the microscopic, they’re absolutely beautiful and intricate.”

What is most interesting is that many kinds of rove beetles evolved independently to live as social parasites in ant and termite colonies, mimicking the colony members in body shape and in the chemicals the beetles produced. They prey on ant young and steal food while masquerading as colony members.

Those lineages transformed in the same way, with the same changes in body shape and chemical gland functioning.

The question of how that transformation occurred again and again was what led Parker to stick with the beetles as the foundation of a scientific career. He worked on fruit flies — the dominant insect in laboratory genetic studies — while he was getting his Ph.D. and afterward. But he did that to gain expertise in genetics and developmental biology that could be applied to the study of the beetles.

It is rare that a new organism is introduced as a model for study in biology, but Parker thinks rove beetles have the potential to answer questions about evolution that other insects, like the ubiquitous fruit fly, Drosophila melanogaster, do not.

“As valuable as knowing everything about Drosophila is, it’s not the whole universe,” he said.