Editing Signalling theory (section)

==Sexual selection==

{{main|Sexual selection}}
When animals choose mating partners, [[trait (biology)|traits]] such as signalling are subject to evolutionary pressure. For example, the male [[Hyla versicolor|gray tree frog]], ''Dryophytes versicolor'', produces a call to attract females. Once a female chooses a mate, this selects for a specific style of male calling, thus propagating a specific signalling ability. The signal can be the call itself, the intensity of a call, its variation style, its repetition rate, and so on. Various hypotheses seek to explain why females would select for one call over the other. The sensory exploitation hypothesis proposes that pre-existing preferences in female receivers can drive the evolution of signal innovation in male senders, in a similar way to the hidden preference hypothesis which proposes that successful calls are better able to match some 'hidden preference' in the female.{{sfn|Gerhardt|Humfeld|Marshall|2007}} Signallers have sometimes evolved [[multiple sexual ornaments]],{{sfn|Møller|Pomiankowski|1993}} and receivers have sometimes evolved multiple trait preferences.{{sfn|Pomiankowski|Iwasa|1993}}