signalling 3- conventional signals + cheats Flashcards
What are the four core components of signalling?
(1) Signal Arm/Actor, (2) The Signal, (3) Receiver/Reactor, (4) Response/Effect
Which reliability solutions did Maynard Smith propose?
(1) Shared Common Interest,
(2) Indices,
(3) Handicaps,
(4) Reputation
What is the key difference between handicap signals and conventional signals?
Handicap signals rely on production costs; conventional signals rely on consequence or social costs.
How can signals be reliable if there is no handicap?
Cheating can arise because not all signals are purely production cost-based; in conventional signalling, social enforcement or punishment must deter cheats.
What is Conventional Signalling?
Signals whose form is arbitrarily related to their meaning, relying on social or consequence costs rather than production costs.
production costs may be low, but cosequence and imposed sactions are costly
how is reliability maintained in conventional signalling?
- Common Interests, no benefit to cheat: Situations like the honeybee dance, where all individuals benefit from monitoring and enforcing reliable signals
- Conflicting Interests, costly consequences to cheating: Examples include the house sparrow where individuals balance resource competition (food) with predatory protection. If cheat/dishonest, then the consequence could be predated.
What is an example of a conventional signal in house sparrows?
The size of a male house sparrow’s bib, which signals social status but is maintained by the cost of cheating (aggression from dominant birds).
How does the honeybee dance illustrate a shared common interest?
Worker bees are closely related, so reliable communication (dance) benefits all, reducing the incentive to cheat.
In conventional signals, where does the main cost lie?
The main cost is in the consequences of being caught cheating, not in producing the signal itself.
How does testosterone relate to hidden costs in house sparrows’ bib size?
Testosterone is required for larger bibs and increases basal metabolic rate, adding a hidden cost, although the actual production of the bib itself is not costly.
What did Moller’s (1987) experiment reveal about artificially enlarged sparrow bibs?
Cheating males (experiment with artificial/painted larger bibs) faced more fights and aggression from true dominants, demonstrating the social cost of dishonest signalling. The increase of more fights in the population also led to more chaos in the group, which was not beneficial at a group fitness level
what are the 2 costs in the house sparrow example, and the implications
- self checking system: cheat for signalling higher dominance = incur more costs from fighting and agression from more actually dominant males = not beneficial to fitness
- socially imposed sanction = more fights and agression = not beneficial for fitness
Indices vs. Handicaps
Indices are signals constrained by physical traits; handicaps are signals made reliable by high production costs.
Why can a threat signal in corncrakes be considered ‘conventional’?
- corncrakes have monotonous calls which are energetically costly and serve as non-agressive calls, and intermittent calls (agressive) but energetically cheap.
- The more aggressive, intermittent call is actually less energetically costly which is counterintuitive as handicap principle would suggest that a reliable agressive signal should be more costly to produce
- proposed reason: the reliability relies on social consequences, not production cost.
Why aren’t house sparrow badges considered handicap signals?
They’re not energetically expensive to produce; their reliability stems from the risk of social punishment, not production cost.
What role does ‘reputation’ play in signalling reliability?
Individuals avoid dishonest signalling to maintain social standing and future cooperative opportunities.
What is the key takeaway regarding conventional signals?
Conventional signals can remain reliable through socially imposed punishment on cheaters, not because they are expensive to produce.
How do common interests maintain reliable conventional signals?
When all parties benefit from honesty, there’s little incentive to cheat, and social monitoring is easier to enforce.
What is the ‘self-checking system’ in social species?
If you cheat by inflating your signal, you risk challenges and aggression from higher-status or stronger individuals, discouraging dishonesty.
Summarize the difference between production costs and consequence costs in signalling.
Production costs (handicaps) deter cheating via inherent energy/material expenditure; consequence costs (conventional) deter cheating via social sanctions.
Why might a seemingly costly signal not be a true handicap?
Because the apparent cost could stem from social consequences or hidden factors, rather than inherent production expense.
What is Dishonest Signalling?
Occurs when a signaller provides false information to a receiver, challenging the assumption of fully reliable communication.
how can dishonest signals be sustained?
- if these signals are rare
- dishonest signals arise because of conflict of interest, even within conspecifics and even with relatives and kin they may have incentive to be selfish (hamilton’s rule)
What does the hornet moth mimicry example illustrate?
- dishonest signalling via mimicry of toxicity when its not
- A palatable moth mimics a toxic hornet’s warning signals, deceiving predators into thinking it’s dangerous.
How do fork-tailed drongos use false alarm calls?
They mimic alarm calls (e.g., of pied babblers) to scare others away from food sources, then steal the food.
* deception
Why is dishonest signalling still tolerated in many systems?
- Dishonest signals exist within honest signals,
- Because honest signals are still generally beneficial for receivers; (negative dependent selection - once cheating signals become common they dont work)
- if cheating remains rare, it doesn’t undermine overall reliability.
4 ways to maintain rarity in signalling systems
1) social control,
2) tactical switching,
3) ecological constraints, or
4) physical limits.
How does social control (reputation) limit dishonest signalling?
Receivers ignore or punish unreliable signallers, discouraging repeated cheating and preserving signal integrity and rarity.
What is tactical cheating and cognitive strategy switching?
Cheaters (like drongos) vary their signals to avoid detection; if one deception fails, they switch to a new call type.
- Repeated identical calls lead to habituation (increased response time initially, then decreased as receivers become desensitized).
- Changing the call type after one or two repetitions renews receiver responsiveness.
How do ecological controls support rare dishonest signals?
When a cheating species (e.g., cuckoo brood parasitism) is rare, hosts or predators don’t develop strong defenses, allowing the deception to work.
Why do physical constraints maintain rarity in mantis shrimp’s dishonest displays?
Only ~10% are moulting (with soft claws), so dishonest ‘threat displays’ are physically rare only 10% probability of them are dishonest, keeping the overall signal system reliable.
What is the Drongo Alarm Call Experiment?
Drongos use ~50 call types. They switch calls when babblers become habituated, renewing the effectiveness of the false alarm.
What did Tom Flower’s study reveal about drongo call switching?
Drongos are more likely to change their call type if the previous attempt fails, increasing success in stealing food.
How does repeated identical false alarm calling reduce its effectiveness?
Receivers become desensitized (habituated) to the repeated call, making cheating less successful unless the call is changed.
What is negative frequency-dependent selection in dishonest signalling?
Cheating remains advantageous only when rare; if it becomes too common, receivers learn to ignore or punish the deceit.
Why do young vervet monkeys often lose credibility?
They frequently give inaccurate alarm calls; adults eventually ignore them, teaching the juveniles to signal more accurately.
Summarize the four mechanisms that keep dishonest signals rare.
(1) Social control/punishment, (2) Tactical switching, (3) Ecological constraints, (4) Physical limitations on when cheating can occur.
What is the key takeaway on dishonest signals?
Cheating exists in many signalling systems, but it generally stays rare due to costs, punishments, or constraints that preserve overall reliability.
What is Batesian Mimicry?
A form of warning colouration mimicry where palatable species copy unpalatable models, relying on predators’ learned avoidance.
How does frequency dependence influence Batesian mimicry?
If mimics become too common, predators learn to distinguish them from the real unpalatable species, increasing predation on the mimics.
Why does strong selection pressure exist for improved mimicry?
As mimics become more common, predators refine discrimination, driving mimics to evolve more accurate resemblance to the toxic model.
What is automimicry within a species?
- When some individuals in a species lack the actual defensive trait (e.g., toxicity) but still display the warning coloration of their toxic conspecifics.
- Automimicry: Automimicry is a type of mimicry where the “model” and the “mimic” are both within the same species
- in monarch butterflies over 60% are mimics
How does the “go slow” signalling concept help maintain automimicry in species with high mimics?
Predators approach cautiously and often sample prey first, allowing them to detect non-toxic cheats by sampling taste, preserving overall honesty in the warning signal.
- Honesty and dishonesty is held in balance by consequences of cheating and not production costs
- once too common, Receivers evolve to discriminate cheats based on actual toxicity not coloration
What did Guilford (2004) Study on Automimicry reveal?
Birds were given visually identical mixtures of toxic and non-toxic prey. They often sampled and rejected non-toxic prey, showing that predators learn to distinguish cheats despite identical warning signals.
Why might ecological distribution help keep automimicry rare?
- example in monarch butterflies which show auto-mimicry, the butterflies laid on toxic plant becomes toxic
- Toxic plants may be rare in general, so fewer caterpillars ingest toxins, ecologically limiting the number of truly toxic individuals and preventing cheating from dominating.
How do negative frequency-dependent effects apply to mimicry systems?
Cheating strategies thrive only when rare; once they become too common, predators adapt, increasing costs for mimics and restoring rarity.
What is the main difference between conventional and handicap signals?
Conventional signals rely on social or consequence costs to deter cheating, while handicap signals depend on inherent production costs to ensure reliability.
What is the Dishonest Signalling Recap?
Cheating (like mimicry or false alarms) is tolerated at low frequencies through social control, ecological or physical constraints, and cognitive strategy switching.
How does warning signal mimicry demonstrate the balance of honesty and cheating?
Palatable mimics gain protection from looking toxic, but if mimic numbers rise, predators learn to discriminate, restoring honesty via increased predation on fakes.
