Lecture 14 - the evolution of communication Flashcards Preview

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2 examples of deceptive communication

1) cuckoo chicks decieve hosts into feeding it
2) moths can mimic hornet/wasps warning colous


example of sexual deception in flowers

- fly and bee orchids - decepts the male of the species into mating with a female because their flower petals look like a female - way for the orchid to be pollinated


example of sexual deception in fish

young male blue gill sunfish deceive older males by pretending to be females and sneak onto the territory to gain extra fertilisations


example of sexual deception in a spider

- bolas spider attracts male moths by mimicking female moths pheremones - this works because the balance of probability that there is gonna be a female at the end of the pheromone trail is higher than the likelihood it will be a spider - the spiders cash in on this


define sexual selection

Female choice selects for male traits that persuade females to mate with them…. This leads to a co-evolutionary arms race between the sexes


what are the 3 main ways that animal signals may be honest/reliable according to maynard smith and harper

1) common interest
2) handicap/ cost
3) index of quality (uncheatable signals)


example of honest communication due to common interests in honeybees?

waggle dance - signal to other members of the colony direction of high quality food source


example of honest communication due to common interests with learned cues

- long tailed tits - cooperative breeders - their calls are individually distinctive - helpers assist relatives - calls carry a kinship signal because you learn the calls from your parents- allows discrimination from kin to kin

this is an example of 'environmental' cues to kinship


example of honest communication due to common interests with genetic cues

' green beard' genes in fire ants
- all egg laying females are Bb- bb females die prematurely
- BB females are killed by Bb workers
-Bb look out for other Bb so they can lay eggs
- it it thought they recognise each other by odour cues (phenotypic effect)


what does a 'green beard' gene do?

1) Causes a phenotypic effect
2) Permits recognition of itself in other bearers
3) Causes differential behaviour towards bearers


who proposed the green beard gene idea?

Richard Dawkins - proposed in his book the selfish gene - the idea that you are nice to other individuals with the same gene


what is an example of unrelated common interest communication?

raven yelling - ravens feed on carcasses - they are dependent on them in the winter to survive - they make a specific call indicating where the carcass is to other ravens


why is raven yelling an example of honest communication?

because normally it would not be within their interest to share the food they have found with others but it is a technique they use when the food is on another ravens territory to overwhelm them so the territory holders couldn't repel them - honest communication favoured by common interests


what were the 3 initial hypotheses for why ravens yell?

1)Attract a “carcass opener” such as a bear (and incidentally more ravens)
2) Selfish herding: attract more ravens in case of predator attack
3)Overwhelm defence of territory holding ravens - the correct hypothesis


another way an animals signal may be honest/reliable is through it being costly/ a handicap to them- what is an example of this?

chicks begging
-Parents often give more food to chicks that beg more
- Begging calls can attract predators
- the more food received by a chick the greater probability of survival
- survival curve shows that hungry chicks benefit the most from begging
- chicks dont constantly beg because the nests are more likely to be predated and it is an energetically costly process


what experiment proved begging to have an effect on predation?

- Artificial nests were more likely to be predated when begging calls played
- the begging of tree nesters, attracts more predators than the begging of ground-nesters - Predation risk is lower in trees than on the ground, so tree nesters beg more loudly
- the ground nesters have a high frequency beg (high frequency sound doesn't travel as far)


what effect does relatedness have on begging?

the cost of begging is less if you are less related to siblings - positive correlation between begging loudness and extra pair percentage


a honest costly signal can also be in terms of display explain this

- higher quality males have a higher probability of survival than low quality
- the signal reduces survival because is it energetically costly to carry a heavy ornament/big display
- females attracted to displays so mating increases
display = honest signal of male quality
= handicap that only high quality males can afford


another way animals signals can be honest is by the the signals being uncheatable - give an example of this

in toads - the deeper the call the bigger size of the male and better their ability to deter rivals - honest signalling to females as they call to attract them


some animals can cheat body size up to a point - give some examples of how they can do this

- Inflating abdomen
- Puffing out chest
- Making hair stand on end
- Elongating larynx to make deeper call

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