Signal Design Rules

• Signal design: features and rules

• Examples– Species recognition– Courtship– Territory defense– Conflict resolution– Alarm

Signal design features• Signal range: context and sender/receiver distance• Locatability: cryptic vs conspicuous• Duty cycle: % on• Identification level: information content -species,

sex, individual• Modulation potential: stereotyped vs graded• Form-content linkage: arbitrary or linked due to

source or other constraint

Mate attraction signal rules

Species differences in cricket calls

Species differences are encoded in temporal patterns

Species differences in bird song

Species differences are encoded in frequency range, INI, note structure

Species differences in firefly flashing signals

Species differences in fiddler crab and fence lizard displays

Species differences in facial patterns

Species differences in

moth mate attractant

pheromones

Convergence in mate attraction signals

• Habitat effects– Bird song: whistles in forest, trills in open

habitats– Lizard head bobbing: bob shape on ground,

interbob interval for arboreal species

• Signaling sex and modality– Males use auditory or visual signals– Females use chemical signals

Courtship signal design rules

Static vs dynamic calling displays

Static components:Convey information aboutspecies differences.Females prefer mode.

Dynamic components:Convey information aboutindividual differences.Females prefer extremes.

Courtship signal and reproductive strategies

• If paternal care is important, courtship is likely to involve nest building or mate feeding

• When females are dangerous, courtship signals are often submissive (e.g. spiders)

• When male dominance is important, courtship signals are often loud, aggressive, and physical

Form-content linkage in courtship

Territory defense signal rules

Territory marking in European

badger

Individual differences in territory defense or status signals

Threat signal design rules

Conflict resolution signals

Alarm signal design rules

Avian alarm and assembly calls

Mammal flee vs alert alarm calls

Californiagroundsquirrel

Belding’sgroundsquirrel

Domesticchicken

Forest guenonmonkey

Visual alarm signals

Across function comparisons

• If design rules are the result of selection and constraints, expect convergence across taxa

• More comparative studies are needed to uncover trends in signal form in relation to social function and sender context

Chemical signal differences across functions

Differences in cricket calls across functions

Seasonal patterns in bird coloration differences

Squid color signals