The theory of evolution explains how animals change gradually over time. But where do completely new traits come from? How did the first eye, the first wing, the first firefly's light organ develop?
A new grant from the National Science Foundation to Indiana University biologist Armin Moczek will help answer this question. An expert on evolutionary development, Moczek recently received over $860,000 to use a tiny insect -- beetles -- to explore a big mystery.
"The big picture is that how novel complex traits originate is still poorly understood, but two routes have been proposed," said Moczek, a professor in the IU Bloomington College of Arts and Sciences' Department of Biology. "A new trait may evolve by repurposing an already existing part of the body -- drawing upon existing gene networks and tissues like combining Legos to build something new -- or by building it 'piecemeal,' one gene and pathway and cell at a time."
Under the grant, Moczek's lab will examine the differences between two types of horns in beetles in the genus Onthophagus: prothoracic horns, which grow from the beetles' mid-portion, or thorax; and head horns, which grow from their heads. The two horn types are useful for this work since evidence suggests each represents one of the two evolutionary pathways.
Specifically, Moczek said that prothoracic horns seem to fall into the "repurposing" category -- most likely emerging from the same gene networks responsible for the growth of wings, among other structures. Head horns, by contrast, most likely evolved "from scratch."
In fact, Moczek and his colleagues' own work on horned beetles -- supported by other NSF grants in 2012 and 2007 -- is responsible for the most compelling evidence on this subject. In a particularly notable experiment, IU researchers were able to create a third functional eye in the center of a beetle's head by switching off a single gene involved in the growth of head horns. Their work has also helped explore the link between nutrition and environment-sensitive development in the same beetle species, and to unravel the role of specific genes in the growth of diverse horn types.
The research under the latest grant will aim to answer two specific questions about creating new traits from scratch versus repurposing existing genes and tissues: How often do new traits emerge through one process versus the other, and how different are they in terms of their ability to generate "spectacular novelty"?
"Ultimately, this work will contrast the mechanisms, efficiency and consequences of innovation via these two routes, and how they may help us understand why and how life on Earth has innovated and diversified the way it has," Moczek said.
The grant will also support several education efforts to engage people beyond IU in the topics under investigation. Building on longstanding partnerships with the local school district and with Bloomington-based children's museum WonderLab, Moczek will work to support Indiana's Academic Standards for Science through the development of course modules based on the grant's topic for dissemination to students across the state through teacher training workshops. This will include modules specifically targeted to English as a Second Language and special education students, Moczek added, noting that both demographics often fall through the cracks.
In addition, the grant will support the work of six junior scientists at the undergraduate, Ph.D. and postdoctoral levels, as well as the recruitment of two high school students per year. The high school students will work on these topics in Moczek's lab through the James Holland Summer Science Research Program, one of three programs named after the late IU biologist James P. Holland for which Moczek serves as a co-director.