image: James Lewis, assistant professor in the Clemson University Department of Genetics and Biochemistry
Credit: Photo by Pete Martin, Clemson University College of Science
Butterflies from the Heliconiini tribe are well-known for their bright wing coloration. The splashes of red, yellow, orange or blue on a black background warn predators of the cyanide-related toxins they sequester in their bodies from their passion vine host plant.
Heliconiine butterfly species that live in the same region often share the same wing color patterns, a process known as mimicry, to increase their individual protection from predators.
It’s an evolutionary strategy that has been extremely successful.
So, why would some Heliconiine butterflies living in Central America evolve to not be mimics anymore?
That’s one of the questions James Lewis, an assistant professor in the Clemson University Department of Genetics and Biochemistry, will try to answer as a part of his $1.3 million National Science Foundation CAREER grant.
The NSF CAREER Award is among the most prestigious in the nation for early-career faculty who have the potential to serve as academic role models in research and education and to lead advances in their field.
“As environmental conditions change, how do populations evolve so that they may continue to exist in the face of this novel pressure? And once they have adapted and become more fit for that environment, how do populations maintain their fitness?” said James Lewis, an assistant professor in the Clemson University Department of Genetics and Biochemistry. “Those are broad, non-organism specific questions that are equally important to humans, fruit flies and your dog. We use butterflies as a model for trying to understand the adaptive process.”
There are two types of mimicry.
Batesian mimicry is when a “harmless” species mimics a dangerous species so predators will leave them alone. Mullerian mimicry is when both species are toxic or unpalatable and predators don’t want to mess with either of them.
“There’s a fundamental idea that mimicry only works if things look like each other,” Lewis said.
But the butterflies Lewis will study have lost some of the mimicry phenotype, meaning they no longer as closely resemble the other species. He will look at the genetics underlying that transition.
“These butterflies are leaving a good strategy that is known to be successful,” he said. “Understanding why and how that happens will help us better understand how organisms adapt to novel selection pressure.
“A butterfly that is brightly colored, but not mimetic, is both easily seen by predators and lacks the protection they previously gained from wing pattern mimicry. This appears, at first glance, to be the worst of both worlds. This is exactly the sort of unexpected change that I want to study,” said Lewis.
Lewis said the knowledge gained through his study of butterflies can help our understanding of how other organisms adapt to changing environmental conditions.
“The process of adaptation uses the same genetic tools independent of what’s actually being adapted. We’re studying butterfly wing coloration and mimicry, but … the fundamental architecture of how this process happens is the same,” he said.
NSF CAREER grants must have an education component.
Lewis plans to offer intensive 10-week internships for undergraduate students to gain proficiency in CRISPR/Cas9 gene editing.
CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) is a technology that scientists use to selectively modify the DNA of living organisms. CRISPR was adapted for use in the laboratory from naturally occurring genome editing systems found in bacteria.
“(CRISPR) changed everything,” Lewis said. “It’s a fundamentally important skill set for anyone that wants to go into the biotech industry and it’s something that is not easy to train in a classroom because it’s a combination of wet skills as well as deep knowledge of a subject.”
CRISPR-Cas9 is a technology that enables geneticists and medical researchers to edit parts of the genome by removing, adding or altering sections of the DNA sequence.