Flashcards in Lecture 9 Deck (27)
assigning human emotions and feeling to animals that don't run with our spectrum of visual and emotional cues.
What are some species in the animal kingdom that suffer limited predatory threat?
Predation is almost ________
among group living species, some individuals may produce what?
vocalizations or other warning sounds to alert the conspecifics in the area to a potential threat (produce a predictable change in behavior among group)
Describe reciprocal altruism?
Some form of cost/benefit assessment
What are some functional hypotheses of alarm calling?
Describe individual selection
Manipulate action of conspecifics
--facilitate group formation and cohesion
--silence group members to decrease predator detection
--reduce chance of future attack
Benefits to individual selection hypothesis?
Alarm signals represent a form of mate investment
--invite predator pursuit
--deter predator pursuit
--confuse predator orientation when alone
Describe the kin selection hypthesis?
warn kin of varying degrees of relatedness
to defend offspring
what's the difference between vocalizations used to attract mates and alarm calls?
vocalizations for mates are easy to locate and are low frequency and have clear start and stop points to help with localization.
--alarm calls need to be difficult to locate
What are some factors that influence the detectability of alarm calls?
Amplitude of the signal at the sound source
2. Attenuation characteristics of the environment
3. Signal-to-noise ratio at the perceiver
4. Discrimination ability of the perceiver against the background noise
5. Auditory sensitivity of the perceiver
why should production capabilities of the sender and perception capabilities of the receivers matter?
Conspecifics must be able to avoid predation
Predators must be confused or challenged by the same signal
__________ noise is easier to localize than __________ noise
broadband, narrowband (pure tones are difficult to localize)
what kinds of calls are more readily localized?
frequency modulated calls (like sage grouse stridulation)
how does environment impose its own effects on signal structure:
most alarm calls under lab conditions (in the absence of broadband noise) appear to be frequency-modulated
the composition of similar species (sympatric species) in a given area should what?
should create a situation where alarm calls overlap; calls should be understood across species boundaries
why should alarm calls show distinct overlap
Since environmental pressures are similar and sound producing equipment is similar;
What did marler observe about alarm calls.
Single, brief duration “seeet” call Low amplitude
High frequency (narrowband)
marler found that alarm calls in birds causes what?
others to seek cover. Alarm calls in different bird species have similar structure:
unlike alarm calls, mobbing calls are made of what?
Repeated series of loud “chuck” calls
Wide range of frequencies (broadband)
Sudden sharp onset and offset
when does mobbing behavior occur?
when predators perch in an area and the threatened species work together to drive away the intruder
what did molar suggest about alarm calls?
shaped by strong selection pressures. Alarm calls reveal a clear trade-off between detectability and localizability
What kinds of sounds are hard to localize?
narrow band of frequencies and gradual onsets and offsets are hard to localize
What are the 5 points of Marler's hypothesis?
1. Small animals are better at detecting high frequencies than larger animals (e.g., predators)
2. Sounds with gradual onsets and offsets are hard to localize
3. Narrowband sounds are harder to localize than broadband
4. High frequencies are linked to fear rather than attack
5. Mobbing calls are repeated in a loud voice to attract others
________ _______ are linked to fear rather than attack.
What is the best course of action for alarm calling?
Use brief, high-frequency sounds without sharp onsets to avoid localization Use longer, more intense, broadband sounds to attract attention