This article is about the evolution of a buzz-run signal in honeybees.  First the researchers give background information and explain the purpose of the signal.  According to the authors, honeybee worker scouts are sent out of their hive to find new, suitable sites for their nests.  When they find a nest site that will work for the hive, they return and perform related piping signals and the buzz-run dance.  This signals the rest of the bees in the current hive to prepare for flight and then swarm to the new nest site.  Apparently the scouts must do a piping run in which they walk throughout the hive and crowd of bees to stimulate the stationary bees to get moving and sample the temperature and determine whether their wing muscles are warm enough for flight.  Then they do the buzz-run, in which they run and start to flap (or buzz) their wings in short bursts to stimulate the remaining bees even more.  The researchers propose that the ultimate goal of these signals is to cause the entire swarm of bees to take off simultaneously and move to the new nest.

            The authors tested their theory using bee hives at Cornell University and having the bees aggregate on swarm mounts, which were flat upright boards that were able to be videorecorded in order to observe bee behavior and view the buzz-running scouts’ effects on the calmer bees.  They also attached a microphone to record sounds produced by the bees and analyzed wing-beat frequency using Raven software.  Bees producing piping signals created high-pitched sounds and had wings folded tightly, while buzz-running bees produced lower sounds and had their wings spread. 

            Although they gave a lot of signal function information to begin with, the authors concluded the article by explaining how the buzz-run signal represents signal evolution.  They confirm a lot of previous research but add that at the end of a buzz-run, a worker bee also takes flight for a few seconds and then returns to repeat the signal.  They explain that the buzz-run is really a ritualized form of actual flight take-off behavior.  Since a bee must inherently buzz its wings to fly, the buzzing served as a cue for other bees, and they associated it with the condition of flight.  Receiver bees detected the buzzing and used it to make decisions about when they should take flight themselves.  This led to hive-wide take-offs that were more in synch and energetically economical, and therefore increased the fitness of both the senders and receivers.  This caused the buzzing cue to become more and more ritualized until it evolved into the signal it is today.  The authors emphasize, as described in lecture, that the original cue has been exaggerated by lengthening the time spent buzzing before actual take-off, simplified by lowering the wing-beat frequency, and added to with the inclusion of things like running and wiggling behavior.  The conclusions fit perfectly with information from our textbook and lecture.  The buzz-run signal evolved as a result of the process of senders associating a cue with a condition, receivers perceiving this cue and also associating it with the condition, and tuning of the signal until it was ritualized to maximize benefits to sender and receiver bees.

Rittschof, Clare C. & Thomas D. Seeley. (2008) The buzz-run: how honeybees signal ‘Time to go!’ Animal Behaviour, 75,189-197.