Eavesdropping Selects for Conspicuous Signals

Lichtenberg, E, J Graff Zivin, M Hrncir, and J Nieh, “Eavesdropping Selects for Conspicuous Signals,” Current Biology, 24(2014) 598-599.

Download PDF

Animal communication signals generally evolve to become increasingly conspicuous for intended receivers. However, such conspicuous signals are also more susceptible to eavesdropping, i.e. exploitation by unintended receivers. It is typically thought that eavesdroppers harm signalers and select against conspicuous signals. But, if signal conspicuousness deters eavesdroppers by indicating a cost, all receivers benefit. This may occur when eavesdroppers exploit food recruitment signals but need to fight for food access. Using eusocial insects, stingless bees, we show that conspicuous signals can indicate competitive costs and enable signalers to escape eavesdropper-imposed costs. The dominant eavesdropper, Triogona hyalinata, avoided higher levels of Trigona spinipes pheromone that indicate a food source difficult to win, and showed attraction to lower pheromone levels that indicate a relatively undefended resource. Our decision-analysis model reveals that eavesdropping individuals that can assess takeover costs can benefit their colony by recruiting to weakly defended resources and avoiding costly takeover attempts.