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13 Cards in this Set
- Front
- Back
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Name the 2 ways evolution acts on signalling, and explain them, and determine whether they are more important in close range or at a distance.
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1. Efficacy: how well the signal is being transmitted. more important at a long range
2. Strategic: what information is being sent in the signal. more important at short range |
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what are three ways to analyze a phylogenetic tree of signal evolution? Wh
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Parsimony analysis
Quantification: looks at difference between genetic distance and trait distance Visual Inspection: can show patterns of trait evolution. |
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Explain the Receiver-precursor model of signal evolution
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due to some sort of sensory bias
the receiver has some sort of sensory bias, when a certain signal stimulates their nervous system, the senders evolve to use this to their benefit and exploit this sensory bias |
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Explain the Sender-precursor model of signal evolution
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1. signal released by the sender, it has some info on sender condition, not intentionally, but ends up being an honest signal of current condition
2. that signal has to be received by the receiver 3. A) Receiving this signal has some sort of beneficial fitness effect, and the ability to send this and receive this signal will be passed on, and often become ritualized. Refinement improves this B) Negative effect on fitness (preds can tell the sender is weak), the ability to receive this signal will be lost, and the sender will evolve ways to try to mask this signal. |
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Define Ritualization
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refinement of an inadvertent cue into a true signal
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list and explain the 4 options of Refinement
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1. Increased Conspicuousness: enhances contrast, movement, and aptitude (ducks bobbing heads)
2. Redundancy: Repetition of coupling components— if a signal is beneficial, then it will be repeated until it becomes ritualized (proves signal isn't an accident, repeats it) 3. Stereotypy: species will do the same type of signal over and over, to reduce variation between males (males doing the same routine shows which one does it best) 4. Alerting components: doesn't give info, but gets receiver ready to receive the signal |
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Moving locomotory or feeding structures Ritualization and example
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Eg: Woodpecker
when they peck at trees for food it sounds different than when they peck at the trees to attract a mate. when mating, they will peck a species-specific beat |
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Intentional movements Ritualization and example
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An animal will send a signal before it performs a behaviour, typically a warning signal. Eg. Snakes Before they attack, snakes will rear up and open their mouths as it would when it attacks, but it will do this just as a signal to warn off intruders |
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Motivational conflicts Ritualization and example
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Different behaviours may reflect different motivations.
Eg. Broadside displays in mammals (bison) when the animal is unsure if it wants to attack, it will show its side, making it look bigger, and hopefully scaring off its opponent. this also shows that it doesn't want an altercation, but isn't scared to fight |
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Autonomic Nervous System Ritualization and example
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some autonomic responses to external phenotypic changes that can become ritualized
eg. goosebumps (piloerection) |
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Define Honest Signals
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signals that accurately describe the current condition of the sender. difficult to fake.
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Why don't animals always cheat on signals?
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"Handicap Principle"
if the signal is easy to produce, and not energetically costly to make, then it won't be selected for (if everyone can do it, why would she want it?) Receivers prefer costly signals takes a lot of energy to send good signals, whether it be metabolic or risking predation |
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Differential Benefits model
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Animals have to weigh out out much of a signal they want to produce
Eg. baby birds want to chirp loud enough to get their mother to feed them, but not so loud that a predator hears them |
