The fact that millions of North American monarch butterflies fly thousands of miles each fall and somehow manage to find the same overwintering sites in central Mexican forests and along the California coast, year after year, is pretty mind-blowing.
The fact that millions of North American monarch butterflies fly thousands of miles each fall and somehow manage to find the same overwintering sites in central Mexican forests and along the California coast, year after year, is pretty mind-blowing.
Once they get there, monarchs spend several months in diapause, a hormonally controlled state of dormancy that aids winter survival. Though diapause is not as obviously impressive as the celebrated annual migrations, it holds mysteries that have perplexed scientists who study biological timing.
Weeks before warming temperatures and longer days signal to the monarchs that it’s time to mate and begin spring’s northward migration, an internal timer goes off like an alarm clock to rouse the insects, telling them it’s time to end diapause and prepare for the critical upcoming events.
Studies in other organisms have shown that cold temperatures can influence the diapause-termination timer, and University of Michigan biologist D. André Green suspected the same is true for monarchs. His study at monarch overwintering sites in central California confirmed it, and his gene expression analyses help explain how cold temperature speeds up that internal timer.
Read more at University of Michigan
Photo Credit: skeeze via Pixabay
