Chapter 13- Communication

Question 1

How do animals communicate in noisy environments?

Answer 1

An environment like the tropics is noisy, so natural selection favors communicating in ways that maximize the chances that auditory signals are not masked. In some rainforests, birds in one species monitor the auditory communication of other species and adjust their own communication so their signals aren’t masked.

Question 2

Communication in neotropical birds (Hart)

Answer 2

Researchers hypothesized that neotropical birds might try to partition the soundscape with cicadas to increase the chances that their signals are not masked. The species of cicada studied signs loudly and creates a range of noises that could mask bird songs. Researchers recorded the songs of cicadas and birds and compared the bird songs before and after cicada songs. The mean number of bird species singing and the mean number of bird vocalizations were significantly lower in the period after the cicadas started singing. Birds used frequencies that didn’t overlap when they did sing at the same time as cicadas

Question 3

Communication

Answer 3

The transfer of information from a signaler to the receiver

Question 4

Does natural selection favor honest or deceptive (manipulative) communication?

Answer 4

Natural selection will favor signalers that send signals in whatever way best increases the fitness of the signaler, even if this means manipulating the recipient. Natural selection also favors recipients who are able to determine whether communication is honest

Question 5

Classic ethological approach of communication

Answer 5

The idea that both parties usually benefit from the information exchange, and there is little selection pressure for manipulation on either end.

Question 6

How do Krebs and Dawkins propose distinguishing between manipulative and cooperative communication?

Answer 6

With manipulative communication, signals should be exaggerated. With cooperative signaling, natural selection should favor less exaggerated signals, similar to conspiratorial whispers. Signaling comes with the cost of energy and drawing attention from predators, so natural selection should favor minimizing these costs with discrete cooperative communication. Honesty might also evolve if the signals being sent are difficult to fake

Question 7

How does communication impact a female’s mate choice?

Answer 7

Females tend to pay attention to honest signals that can’t be manipulated when choosing a mate. In toads, male toads are unable to fake deep croaks, as their croaking depends on the physiology of their vocal system. Females use this characteristic when choosing mates

Question 8

Zahavi’s handicap principle

Answer 8

If a trait is costly to produce, it might be used as an honest signal, because only those individuals that can afford the cost will use that signal. Individuals who fake this characteristic demonstrate that they are good at gathering resources, which is still a beneficial trait

Question 9

Relationship between vocalization and group size in primates

Answer 9

Researchers examined literature and compared vocalization repertoire (number of different vocalizations used) and group size. There was a positive correlation between the 2 variables. This could be because as group size increases, the benefits of having a larger repertoire of sounds to communicate with a group increases. The study was correlational, so it’s not clear which variable came first

Question 10

What coordination problems are faced when animals forage in groups?

Answer 10

When new food sources are found, information needs to be transferred to group members if the transfer is beneficial to the signaler

Question 11

Food calls in cliff swallows

Answer 11

Breeding cliff swallows live in nests that act as information centers. Researchers studied whether individuals are recruited to food sites. They found that cliff swallows gave of “squeak” calls, which alerted other members of the species that a new food patch had been found. These calls were only emitted in the context of recruiting others to the food site. Recruiters benefit from calling because the increased group size that comes from recruiting means that other group members will find more food and provide more foraging opportunities

Question 12

Food calls in ravens

Answer 12

Ravens are scavengers that can survive for days if they uncover a food patch. When they find a food source, they emit a loud yell that attracts other ravens. Yelling is partly associated with hunger level- hungry birds yell more often. Yelling also attracts juvenile ravens so they can overpower adult ravens and get food

Question 13

Communication and learning in ravens

Answer 13

Ravens communicate about food when they roost together at night, and this communication seems to involve learning. Researchers studied ravens that formed roosters near a newly discovered food source. They found that these roosts and mobile and move to where new prey has been discovered. These mobile roosts serve as information centers that provided roostmates with the chance to share information they discovered about prey while they were away from the roost. Knowledgeable birds tended to lead naive birds to prey when the birds all leave the nest together. Birds who didn’t know about the prey environment would act as followers

Question 14

Honeybee waggle dance

Answer 14

Bees perform a re-enactment of their journey to a patch of flowers, so other bees can learn the distance, direction, and odors of the flowers and fly to them. The longer the bee dances, the farther away the food patch. The waggle dance benefits honeybees because honeybees are all closely related, an individual relaying information about food increases their inclusive fitness. Bees also utilize different types of dances based on the distance of the resources from the hive- waggle dances are used for food that is very far away, and the transition across dance types seems to be controlled by a single genetic locus

Question 15

Development changes associated with the honeybee waggle dance

Answer 15

Researchers examined how hive temperature during development affected the waggle dance behavior of bees. Bees were matured at different temperatures and then placed in foster hives. Bees who matured at 32 degrees were less likely to use the waggle dance when they returned to the hive then bees from the other treatments. They used less circuits when they did use the waggle dance. Bees maturing in the 36 degree treatment were better at individual learning tasks. Lower temperatures seem to lead to bees that are poor foragers and poor communicators, which means they provide less energy for the hive and results in lower hive temperatures (resulting in more poor foragers)

Question 16

Which chemical cues cause bees to leave a hive to forage in response to the waggle dance?

Answer 16

4 different hydrocarbons were emitted by bees during waggle dances. When bees were exposed to the synthetic version of the hydrocarbons, they were more likely to leave the hive. Therefore, the hydrocarbons were probably associated with foraging

Question 17

How do ants communicate with others in their foraging group?

Answer 17

Using chemical markers and sound production through vibrations

Question 18

Which chemicals are used for communication in ants?

Answer 18

Methyl 4-methylpyrrole-2-carboxylate and 3-ethyl-2,5 methylpyrazine are important for long distance foraging communication. These compounds are produced in the poison gland of leaf cutter ants and are used to recruit other workers to foraging sites a long distance from their nest. Powerful recruitment hormones are also placed along trails leading to where ants need to harvest leaves

Question 19

Stridulation use for communication in ants

Answer 19

A type of communication used by ants to determine the exact leaves they need to cut. Researchers hypothesized that the ants raise and lower parts of their abdomen to create stridulatory vibrations, and that ants used the vibrational cues to recruit other workers to the best leaves, so the nest would have access to high quality food. They found that workers were stridulating while cutting leaves, and the vibrations were sent along the leaf. Ants were also more likely to stridulate with tender leaves than with tough leaves, and very likely to stridulate when the leaf was dipped in sugar water. Stridulation was used for recruitment, since ants were more likely to cut vibrating leaves

Question 20

Minim workers

Answer 20

A caste of leaf cutting ants that can’t cut leaves, but ride on the backs of leaf cutting workers. Minims are beneficial because they protect other ants from attacks by parasitic flies. Minims can use vibrational cues to find the leaf cutters

Question 21

2 types of communication used in sexual selection

Answer 21

1. Vocal communication
2. Tactile communication

Question 22

How do female cowbirds use bird song to choose mates?

Answer 22

Females may use the size of a male’s song repertoire to choose between mates. Researchers exposed female birds to 5 different song treatments with different repertoires. The length of time that a female exhibited copulation-solicitation displays to different songs were measured. Females had longer CSDs when hearing songs from males of their own species, and when exposed to longer repertoires

Question 23

Phylogenetic relationship between sexual selection and birdsong

Answer 23

Researchers mapped 6 components of birdsong onto a molecular phylogeny of multiple species of blackbirds. They found evidence that evolutionary changes in song were most often associated with sexually dimorphic and polygamous species (males are larger than females), where sexual selection is strong. In the branches of the tree where there were changes in song components, males were at least 15% larger than females. Strong sexual selection and competition for access to females means that natural selection acts strongly on the many components that make up male song

Question 24

What is the proximate basis of birdsong?

Answer 24

The syrinx is the vocal organ in birds. It has left and right compartments that can be controlled independently by the two sides of a bird’s brain. The syrinx doesn’t really vary in structure, but its parts can be changed to create new combinations and new sounds. Independent control of each compartment means that birds can switch off one side at any time, and switch which side dominates in specific situations. In addition, variance in the structure of respiratory muscles and in labia tissues and variance in how they’re used can affect the structure and timing of birdsong

Question 25

Ripple communication in water insects

Answer 25

Water striders produce ripples through up and down movement of the legs. Waves with different amplitudes and frequencies are used for different behaviors- includes signals for calling mates, territoriality, and copulation. Females find some signals produced by males attractive, and could grasp males and lay eggs in response to playbacks of calling signals experimentally. Researchers also hypothesized that ripple calls to attract mates could also help with species identification. Certain species of water striders are found in the same streams and ponds as other water striders

Question 26

Vervet communication

Answer 26

When they sight a predator, vervet monkeys emit specific alarm calls for specific types of danger, and different calls elicit different responses by groupmates. They will often emit a specific call for a specific predator, so their groupmates can then exhibit antipredator behavior that’s specific to the danger of that predator (climbing trees in response to leopards, etc)

Question 27

How do elephants protect themselves from harm?

Answer 27

They are able to use human voice to determine the level of threat the human poses, and they then exhibit the appropriate defensive response. The defensive response is greater when they hear groups of people that pose a greater threat, like those that have conflict with elephants

Question 28

In which situations does natural selection favor young individuals learning communicative signals from adults?

Answer 28

When parental care is present and lengthy, natural selection favors developmental pathways where young individuals can learn communication from adults. In vervets, where signals are complex, young individuals learn alarm calls from adults. This also occurs in meerkats because pups face predation as soon as they move above ground after the first few weeks of their life

Question 29

Development of the response to alarm calls in meerkat pups

Answer 29

Researchers found that pups were initially more likely than adults to ignore alarm calls emitted in the presence of dangerous predators. Pups don’t always react appropriately to alarm calls like adults do. However, after hearing an alarm call, pups would move to shelter when they observed adults scanning for predators. As pups learn about alarm calls and predators from adults, they exhibit adaptive responses to alarm calls

Question 30

Ignoring alarm calls in ground squirrels

Answer 30

When alarm calls become less reliable, natural selection should favor paying less attention to them. In one study using ground squirrels, one treatment exposed the squirrels to recorded alarm calls followed by a predator. The other treatment heard the alarm call, but did not see the predator. Initially, there were no differences in response to alarm calls. After 5 calls, squirrels hearing unreliable calls were less likely to look in the direction of the call. After 10 calls, squirrels in the reliable group responded to alarm calls by remaining vigilant and looking the direction of the call. Squirrels in the unreliable group ignored the alarm calls

Question 31

Honest interactions

Answer 31

Those in which both the sender and the receiver obtain a fitness benefit

Question 32

Eavesdropping

Answer 32

Occurs when the sender pays a fitness cost but the receiver receives a fitness benefit

Question 33

Deceitful signals in fireflies

Answer 33

Female fireflies can kill a male firefly that she lures to her by imitating the timed flash response given by females of his
species.

Question 34

3 types of honeybee dances

Answer 34

1. Round dance: when food is near by
2. Sickle dance: when food source is at a greater
   distance
3. Waggle dance: when food is very far

Question 35

Male bird plumage as an honest indicator

Answer 35

Sexual selection, through intrasexual selection, favored elaborate coloration, size and arrangement of bird feathers, or appendages as an honest signal of good genes. The flamboyant colors make it easier to find a mate

Question 36

Mate preferences for a novel ornament

Answer 36

The “white-plumed” male zebra finches were outfitted with
bizarre white plumes. The “white-plumed” male zebra finches were more attractive to females than were control males without plumes or males given headdresses of red or
green feathers.