1. Signal Evolution Process Sender preadaptations –Visual Intention movements Motivational conflicts Autonomic nervous system –Auditory –Chemical Receiver preadaptations

2. Signal Evolution Pathways

3. Ritualization Refinement of an inadvertent cue into a signal Likely requires fitness benefits to sender and receiver Involves –simplification or reduction of number of components –Exaggeration of remaining components –Repetition of the display –Stereotypy during repeated renditions

4. Ritualized preening in duck courtship Shelduck preens in conflict situations, mallard preening is partially ritualized during courtship, garganeya and mandarin ducks simply point to colored wing patches

5. Ritualized courtship in ducks Mallards use 8 displays Bahama pintail and shoveler use 1 or 2 displays

6. Sender precursors of visual signals Intention movements Motivational conflict –Ambivalence behavior –Displacement behaviors Autonomic processes Co-option from other displays

7. Food advertisement and pheasant courtship displays Males give food calls and feed mates in Bobwhite quail

8. Flight intention and courtship in pelecaniforms

9. Antithetical displays Aggressive displays usually reflect attack preparation movements

10. Motivational conflict in wolves

11. Ambivalent threat displays

12. Displacement Acts

13. Displays from autonomic responses

14. Display co-option Subordinate male appeasement display mimics soliciting female

15. Sender precursors of auditory signals Visual courtship displays –Woodcock, grouse displays Defensive antipredator acts –rattlesnake Foraging movements –Mosquitoes, woodpeckers, beaver Respiration –High tension vocal chords = whistle, low tension = harmonic series

16. Antithetical vocalizations

17. Motivation-structure patterns

18. Repertoire evolution in sparrows

19. Sender precursors of olfactory signals Dietary signals –Secondary plant defense compounds Reproductive precursors and products –Estrogen and metabolites Defensive chemicals –Alarm substances (fish, ants, bees and wasps) Novel mate attraction pheromones

20. Bark beetle mating pheromones

21. Receiver bias and feature detectors Feature detectors are receiver refinements that improve signal detection in noise Feature detectors allow for invariant responses and require no learning Provide explanation for sign stimuli and supernormal stimuli

22. Feature detectors

23. Innate releasing mechanisms Herring gull chicks use a moving red spot on bill as a sign stimulus to recognize their mother. A yellow stick with red spots acts as a super normal stimulus.

24. Receiver precursors to signal evolution Sensory drive –Environment influences signal form and receiver design –Favors senders giving conspicuous signals Sensory exploitation –Receivers have latent preferences, e.g. females like to eat red berries –Senders produce signals to exploit this preference

25. Signalling may vary with habitat Phylloscopus warblers

27. Sensory exploitation

28. Water mite courtship evolution T = male trembling mimics copepod prey N = female net stance

29. Female preferences evolved prior to male swordtails Phylogeny based on morphological data

30. or do they? Phylogeny based on mtDNA sequence data Black = swordtails White = no sword Hatched = ambiguous