Chapter 8: Principles of Communication

Question 1

What is a signal

Answer 1

a specially evolved mechanism that contains info to MODIFY the behavior of the receiver.

Question 2

difference between a “signal” and other forms of communication

Answer 2

a signal is a “Specifically evolved message” which ELIMINATES cases where the behavior of one animal influences that of another WITHOUT an evolved message being involved (ex/ a mouse ruffling in the leaves while foraging is not “signalling” to the owl that he is there, the ruffling is just a random by product of eating)

Question 3

For a signal to be sent, there has to be a net benefit to the :

Answer 3

SENDER, but not necessarily the receiver.

That is, benefits exceed costs for the sender. At least some of the time the signal must be beneficial. However, even though there are benefits there may be costs for the sender too.

Question 4

Honest signalling

Answer 4

a “cooperative interaction” between two individuals. The sender benefits from signalling, and the receiver may also benefit. (+/+)

Question 5

Deceitful signalling

Answer 5

when a sender uses a specifically evolved signla to MANIPULATE the behavior of a receiver such that the sender receives a BENEFIT but the receiver pays a FITNESS COST (+/-)

Question 6

which types of signalling are considered “communication”? Why?

Answer 6

both honest signalling and deceitful signalling, because in both cases, the sender uses a specifically evolved signal to positively influence its own fitness.

Question 7

Eavesdropping

Answer 7

when the sender pays a fitness cost but the receiver receives a fitness benefit (-/+) ex/ when the mouse is making ruffling sounds while foraging, the owl hears this and locates the mouse). –> the mouse gives off UNINTENTIONAL CUES rather than SIGNAL, which is an INTENTIONAL transfer of information.

Question 8

Unlike honest and deceitful signalling, eavesdropping involves info transfer via ___ rather than ____.

Answer 8

Unlike honest and deceitful signalling, eavesdropping involves info transfer via CUES rather than SIGNALS.

Question 9

how do cowbird broods utilize deceitful signalling?

Answer 9

they have an exaggerated begging display that induces the host foster parent to feed it.

Question 10

what type of info is communicated in a stable manner over time? What about info that is communicated in a variable manner?

Answer 10

stable manner: species identity, sex, toxicity

variable manner: hunger, health status, dominance rank.

Question 11

senders can transfer either ___ or ___ info

Answer 11

motivational information about themselves (when courting potential mates, or REFERENTIAL info about a specific object (warning others about a predator via alarm calls, or a honey bee waggle dance)

Question 12

the honey bee waggle dance is an example of a sender communicating ____ information

Answer 12

REFERENTIAL info (about a specific object, in this case, food location)

Question 13

Explain how the waggle dance communicates food

Answer 13

dances occur on a VERTICAL SURFACE. the deviation from the upward vertical equals the deviation of the food source from the direction of the sun from the hive.

Question 14

Two hypothesis as to why a signal may evolve

Answer 14

1) preexisting trait hypothesis

2) preexisting bias hypothesis

Question 15

outline the preexisting trait hypothesis for signal evolution

Answer 15

a signal evolves through the senders’ preexisting traits, which are behavioral,physiological or morphological characteristics that laready provide informative cues to receivers and can be MODIFIED into a signal in a process called ritualization

Question 16

Which type of signal evolution hypothesis involves ritualization?

Answer 16

preexisting TRAIT hypothesis outlines how previous traits can be modified to make a signal through a process of ritualization.

Question 17

example of ritualization

Answer 17

piloerection. the fluffing of feathers or hair (preexisting trait) that can be ritualized to signal a message. Ex/ a cat may engage in piloerection to signal aggressiveness.

Question 18

outline the preexisting bias hypothesis for signal evolution

Answer 18

signals evolve through RECEIVERS’ preexisting biases, which are biases in their sensory systems that detect some features of the world better than others and that can be expolited by sender signals by a process of SENSORY EXPLOITATION

Question 19

when communication signals originate in actions that activate sensory ___ and ___ of receivers that are already in place, the result is often due to what is called ___ ____

Answer 19

when communication signals originate in actions that activate sensory ABILITIES and BIASES of receivers that are already in place, the result is often due to what is called SENSORY EXPLOITATION

Question 20

what is sensory drive

Answer 20

a process that allows for signals to be fine-tuned to the specific environment. sensory systems of the receiver are under natural selection to optimize these behaviors within the constraints of their habitat: sensory systems have biases such that they detect some features of an organism ‘s world better than others.

therefore, receivers tend to have preexisting detection biases to certain stimuli in the environment due to sensory drive, which arose before the evolution of the signal.

ex/ tuning of female midshipman hearing seasonally to the range of male humming.

Question 21

what is a sensory trap

Answer 21

when a signal that mimics the features of environmental stimuli exploits the associated receiver response (ex/ lights from angler fishes manipulate other fish to come close enough to be eaten)

Question 22

Panda principle

Answer 22

natural selection does not start from scratch, but instead acts upon what already exists.

ex/ descent with modification is responsible for the sexual behavior of a parthenogenetic whiptail lizard. (asexual females). In this species, a female is counted and mounted by another female. Females subjected to pserudomale sexual behavior are much more likely to produce a clutch of eggs than if they do not receive this sexual stimulation from a partner.

Question 23

extra androgen hypothesis

Answer 23

the female pseudopenis (clitoris in humans) develops as a result of the exposure in utero to androgens.

Question 24

How did von frich test distance communication in bees?

Answer 24

he trained bees to come to a feeding station 750 m from the hive. he collected all newcomers arriving at feeders placed at various distances from the hive. In this experiment, more newcomers were counted at the 750m station, indicating that the trained bees communicated to new bees the location of the 750 m food station.

Question 25

explain the evolution of the waggle dance in bees

Answer 25

1) hypothesized that DISTANCE to a food source was initially encoded by the degree of activity by a returning food-laden worker
2) selection acting in some species may have favored standardization of the SOUNDS AND MOVEMENTS made by successful foragers. Set the stage for dances.
3) direction of food might have originated with a worker guiding a group of recruits.
4) less and less guidance until the proper DIRECTION was communicated with a waggle run on a HORIZONTAL surface (A. Florea)
5) the horizontal dance evolved into a vertical dance to convey the DIRECTION of the food source RELATIVE TO THE SUN and gravity ( A. Mellifera)

Question 26

two ways bees communicate

Answer 26

1) dancing
2) scent marking (in some species, foragers could not recruit new forageres to the site until a rope was strung across the pond. then scouts places scent marks on the vegetation hanging from the rope.

Question 27

sensory drive is likely to be important for signal evolution when the constraints on the signalling environment are ___. provide an example

Answer 27

extreme (ex/ low light environments promotes the development of acute eye sight or better hearing by receivers).

ex/ water mites in low light. Females wait for copepod to produce vibrations to she can eat them. Male water mites approaches and waves a trembling forelef in front of her, setting up water vibration similar to those a copepod might make. the female may respond by grabbing him, but she will release him unharmed. The male then deposits spermatophores on the aquatic vegetation in front of the female before waving his legs over them

Question 28

explain the relationship between food, carotenoids and mate preference in guppies. What type of signal hypothesis does this fit under?

Answer 28

males have to acquire orange pigments from their foods in order to incorporate carotenoids into the pigment patches of their body.

Females find these orange patches more appealing. Males are using SENSORY EXPLOITATION (preexisting bias hypothesis) because the females are sensory-driven to be drawn to orange patches, as they reflect well in the water medium and used to convey good food.

Question 29

explain the sensory exploitation in a mouthbrooding cichlid.

Answer 29

the male cichlid anal fin has large spots on it that mimics eggs. the female normally broods eggs and fry in her mouth. when she is spawning, she picks up her eggs immediately after. If she sees the “eggs” on the males anal fin, she may try to pick up the eggs on the fin, and the male squirts his sperm, fertilizing the eggs in her mouth.

He is using sensory exploitation because sensory drive in the female makes her receptive to placing things thta look like eggs in her mouth.

Question 30

explain an example of how sensory eploitation may occur in predator-prey systems where predators exploit sensory biases of potential prey

Answer 30

ex/ in angler fish
ex/ in spiders. the bright spots and color pattern of the spider nephila pilipes appear to attract prey to the predator at night.

Question 31

in zebra finches, females were more attracted to males who had a white ornament glued to their head. This mate preference for a novel ornament is an example of:

a) preexisting trait
b) preexisting bias.

Answer 31

b) preexisting bias. the females exhibit a SENSORY bias that makes them more interested in novel stimuli, even though we don’t really know what the appeal is.There is no clear adaptation for having a fake white plume on the head of a male.

Question 32

explain sensory exploitation in swordtails.

Answer 32

males have been selected by females because they have a sensory bias towards long and colorful tails.

we know there is a preexisting sensory bias going on mc modern day platyfishes lack a sword and are closer to the ancestral (swordless) fish than sword tails. Yet, female platyfishes prefer males with artificially added swordtails: it appears that there is a pre-existing sensory bias for swordtails lurking in this group of fish.

Question 33

Who benefits from honest signalling?

Answer 33

both the sender and the receiver.

Ex/ ritualized displays: allows you to evaluate scenario and your rate of success if the sender is honestly signalling about his size/fighting ability.

Question 34

What does honest signalling about size convey

Answer 34

the sender (larger male) can convey size. THis is a benefit to him because it shows hes dominant. this is also beneficial to the receiver (smaller male) because he won’t waste his time and energy in a battle they are not likely to win.

Question 35

How do male deer engage in honest signalling?

Answer 35

antler size in male deer provide honest signals about their fighting ability and strength.

antlers = ritual display and honest signal. the smaller the antler, the smaller the buck and most likely weaker. probably will lose.

Question 36

How do collared lizards engage in honest signalling?

Answer 36

the larger the patch of UV light reflecting skin by the open mouth if a gape-displaying collared lizard, the harder the repitle can bite an opponent. The amount of UV skin provides an honest signal about bite strength.

Question 37

how do barking geckos use honest signalling?

Answer 37

they give off honest acoustic signals. The larger the male, the lower the frequency of its calls. The larger the body size, the lower the freqency, indicates superiority in male geckos.

Question 38

how do male toads use honest signalling?

Answer 38

when a male finds another male mounted on a female, he tries to pull him from her back. Mounted males croak when they are touched.

the deep croak is an honest signal of superiority because the male is larger.

vocal croaks are important because studies show that smaller males are less likely to be displaced if they have deeper croaks.

Question 39

honest signal hypothesis

Answer 39

the idea that an honest signal can convey the quality of the sender (usually male), facilitates decision making by the receiver (female or small male), and cannot be easily produced by the sender.

If the honest signal hypothesis is correct, we expect that small males cannot make as elaborate threat displays as large males.

Question 40

explain how side blotched lizardsd have an honest signal of endurance

Answer 40

the duration of a males display and the number of pushups he performs is indicative of ability to perform activities that require endurance.

Question 41

why can’t honest signals be “cheated”? (two types of costs)

Answer 41

because they have 1) PRODUCTION COSTS. Some animals merely cannot convey a signal because they are smaller/of lower quality/younger.

they may also have 2) MAINTENANCE COSTS: the signal is hard to maintain due to SOCIAL REINFORCEMENT, but they are not costly to initially produce.

ex/ dominant female wasps have black markings, which aren’t hard to produce, but result in them getting challenged by other colony members more frequently.

ex/ maintenance costs in male red-winged black birds; dominant males have big red epilets, signifying dominance, BUT: they get challenged more. if a more dominant male comes along, the weaker males may cover his epilets.

Question 42

what is multimodal signalling

Answer 42

when an animal uses multiple signals simultaenously, often so senders can communicate with several different TYPES OF RECEIVERS.

ex/ long tail and collar area in red collared widowbirds. there is a negative relationship between tail length and collar colour in male red- collared widowbirds.

-risk of signal being misperceived. sending more than one signal conveying the same message reduces risk of message being confused by the receiver.

Question 43

Explain the multiple message hypothesis

Answer 43

explains that MULTIMODAL signalling involves different signalling modalities to convey DIFFERENT INFO

ex/ baby birds cheep and flap their wings. the cheep is to send parents for more food, and the wing flapping is to determine who gets the food once its there.

Question 44

explain the redundant signal hypothesis

Answer 44

explains that multimodal signalling involves different signal modalities independently convey the SAME INFO providing insurance for signalling erros or environmental noise.

ex/red collared widow birds, who have red epilets AND long tail feathers.

Question 45

two hypotheses that explain the MALADAPTIVE RESPONSES (WRONG RESPONSES) to signals, and examples

Answer 45

1) novel environment hypothesis: the current environment is sufficiently different from that in which the behavior is evolved that there has not been enough time for the species to adapt (ex/ male jewel beetle mating with beed bottles, or sea turtle eating a plastic bag because it looks like a jelly fish, or birds crashing into windows when the lights are on in a house)
2) net benefit hypothesis: a sensory mechanism that may result in fitness losses for some individuals under some circumstances does not erase the fitness gain that receivers derive ON AVERAGE for reacting to a sender in a particular way . (ex/ femme fatales in fireflies: usually the male benefits, but sometimes he gets eaten), or sexual deception of thynnine wasps by elbow orchids.

Question 46

give an example of eavesdropping

Answer 46

tungara frogs and fringe-lipped bats. tungara frogs croack to attract females, but the bats can eat the male tungara frogs because they intercept the signal (bats are the illigitamate receiver of the signal)

Question 47

Explain the dilution effect in tungara frogs

Answer 47

the chances of being preyed upon declines when male frogs are in a large group. male male competition drives riskier behavior and the frogs continue to make loud calls even though it attracts bats.

Question 48

explain how predation risks has affected communication signalling in birds

Answer 48

ground nesting speices have HIGHER frequency calls because they are less locatable and cannot travel as far.tree nesting speices can have longer-travelling calls because they are safer from predators– allows parents ot hear their children from farther distances.