Monarch butterflies have been known to travel great distances each year from as far as the northeast and Canada to just a few mountainous regions in Michoacan, Mexico. This is a round trip journey that takes place like clockwork. It is known that this journey is governed by the butterfly’s circadian rhythm and the sun’s movement. However, there are a number of questions about this journey left unknown. Christine Merlin, a newly hired biologist at Texas A&M University, is studying this phenomenon and focusing on the role of internal clocks to this migration.
Merlin, who began this fall as an assistant professor in the Department of Biology and is a member of the Center for Biological Clocks Research, notes, “It’s incredible how such a fragile insect can complete a long-range migration so demanding. Every piece of it fascinates me, from how it occurs to why they go precisely where they go.”
When Dr. Merlin was a postdoctoral researcher at the University of Massachusetts Medical School under the direction of Professor Steven Reppert, she and her colleagues were able to demonstrate that the clocks for flight orientation involved their antennae. This was a parting from conventional thoughts that the brain controlled the behavior. It was thought that the brain controls behavioral rhythmicity in every other animal and that includes humans.
Some 50 years ago, an entomologist named Fred Urquhart discovered that Monarchs became disoriented after he cut off their antennae. Since that time, it has remained just a suspicion that the antennae were responsible for the migratory behavior until the researchers at Massachusetts confirmed it with a follow-up experiment.
In the current study, Merlin and colleagues were able to use technology Urquhart didn’t have. They made use of a plastic barrel-like device known as a Mouritsen-Frost flight simulator. The Monarch is connected by tungsten wire to an output system that has the ability to determine which way the Monarch is flying. The researchers observed that Monarchs who didn’t have antennae flew in all directions and those that had antennae flew southwesterly (the migration direction).
Dr. Merlin comments, “What I’m interested in looking at now is the role of the circadian clock in the induction of the migration. Migration begins every year in the fall, when the day lengths change. The shortened day lengths might be a cue for the Monarchs to start their migration. And if we can show this is the case and that the circadian clock is involved, we can now start to understand the genetic program that is allowing the migratory behavior.”
Dr. Merlin is interested in developing genetic approaches that hopefully will lead to an understanding of the genetic basis of this migration. When she was at the University of Massachusetts, researchers there sequenced the Monarch genome. She began developing genetic tools that allowed her to disrupt the Monarchs genes in vivo (similar to mice knock out models).
Dr. Merlin has an advantage in working in Texas in that the Monarch migratory route comes through Texas in both directions. The Monarchs will be back this spring on their way back north.
To learn more about Merlin’s research, visit http://www.bio.tamu.edu/FACMENU/FACULTY/MerlinC.php