When is a Butterfly like an Elephant ?
The behaviour of organisms as diverse as elephants and butterflies are affected by pheromones with similar or identical structures. Recent developments in the molecular biology of pheromone detection suggest why.
The recent report that female Asian elephants release (Z)-7-dodecenyl acetate in their urine to signal that they are ready to mate, is by any measure an extraordinary discovery 1. Who would have predicted that the largest living land animal would have the same pheromone as the turnip looper, the cabbage looper and at least a 100 other species of butterflies and moths (Lepidoptera) 2? (Z)-7-dodecenyl acetate is the fifth most common attractant for Lepidoptera and has structural features that are typical of the majority of Lepidopteran pheromones. The data in Table 1 is taken from an analysis of 2,292 attractants from 1,068 species using the computer program; PherFind (D. R. Kelly, unpublished work) 3. The structures are aligned to show the most common position for alkene bonds, which is at omega-5 and omega-3. (Photo courtesy of Chester Zoo, UK )
This is not the first "coincidence" of this kind. There are several cases scattered throughout the literature in which organisms from diverse parts of the natural world use similar or identical compounds for communication. Are they truly coincidences or are there deeper reasons for the similarities across species? Here I discuss several particularly striking examples of such similarities, and the clues they may offer us about pheromone signalling pathways.