Each fall, millions of monarch butterflies from across the Eastern United States use a time-compensated sun compass to direct their navigation south, travelling up to 2,000 miles to an overwintering site in a specific grove of fir trees in central Mexico. Scientists have long been fascinated by the biological mechanisms that allow successive generations of these delicate creatures to travel such long distances to a small region roughly 300 square miles in size. To unlock the genetic and regulatory elements important for this remarkable journey, neurobiologists at UMass Medical School are the first to sequence and analyze the monarch butterfly genome.
Analysis of the combined genetic assembly revealed an estimated set of 16,866 protein-coding genes, comprising several gene families likely involved in major aspects of the monarch’s seasonal migration. The novel insights observed by Reppert and colleagues in the newly sequenced monarch genome include:
- identifying genes involved in visual input and central processing by the sun compass;
- a full repertoire of molecular components for the monarch circadian clock;
- all members of the juvenile hormone biosynthetic pathway whose regulation is critical for a successful migration and which shows an unexpected regulation pattern;
- additional molecular signatures of oriented flight behavior;
- monarch-specific expansions of odorant receptors potentially important for long-distance migration;
- and a variant of the sodium/potassium pump that underlies a valuable chemical defense mechanism to fend off predators during the migration.
edited from Monarch butterfly genome sequenced.