Communication Continued…

Selection acts to keep signals honest

Signal Deception

ex. Male Photinus flies flash to attract females of their species, but sometimes a species of another species, Photuris responds to his signal. The female eats the male, ultimately using his signal against him.

Why do some animals do the wrong thing?

  • They won’t be able to mate
  • An adaptation doesn’t have to be perfect, it just has to contribute more to fitness on average compared to other alternative traits.

Novel Environment Theory

  • They evolved to do a certain thing but things in the environment change. There hasn’t been enough evolutionary time for the animal to catch up to this changed environment.
  • Maladaptations- Doing something that decreases an animals fitness.
  • ex. A sea turtle eating a plastic bag instead of a jellyfish because when they evolved that wasn’t a problem.

Net Benefit Theory

  • If you don’t respond to the signal then you will never mate. The benefit outweighs the cost. Sure some males will get eaten but most will mate.

Illegitimate signalers are typically trying to fool a member of another species. 


  • When animals use another animals call to locate them and eat them.
  • Eavesdropping influences the evolution of bird calls