Animal Behavior Exam 2

Weber’s Law

the just noticeable difference (JND) between stimuli remains proportional to the magnitude of the stimulus

Risk-Prone Foraging

every food item is worth more than the last, because you’re on the brink of starvation; choose riskier patches in case of higher reward

Risk-Averse Foraging

eat a lot? The value of the next food item is worth less, and less, and less; choose more reliable patches

Time Discounting

animals value immediate small rewards more than large, delayed rewards; later isn’t promised; immediate gratification

Honeybee Waggle Dance

indicates food is more than 50 meters away; tells you direction from hive based on angle of the sun; tells you distance from the hive (closer with more completions + louder buzzing); tells you quality of food (trophallaxis and dance speed – faster = better)

Honeybee Round Dance

indicates food within 50 meters of the hive

Social Facilitation through Local Enhancement

the presence of a model, regardless of what it does, facilitates learning on the part of an observer by changing the observer’s behavior; an individual is drawn to a particular area because it observed another individual in that location

Philopatry

tendency for animals to stay in or return to a particular area

Seasonal/Migratory Philopatry

specific predictable stopping points on annual migratory routes; not where you’re breeding, but a place you go to every year

Natal Philopatry

return to or stay in place of birth to breed

Ideal Free Distribution

Fretwell and Lucas, 1970; animals allocate themselves in areas where their gain will be the highest; several assumptions

Status Badges

signals that reveal information about an individual’s size or dominance status; typically not costly to produce, but might be costly to maintain due to social enforcement, (maintenance cost); ex: paper wasps signal fighting ability by markings on their face (bigger wasp = more black coloring)

Hawk-Dove Model

hawk strategy is to always escalate fights, dove strategy is to never escalate fights; can quantify and predict population changes between hawks and doves; when a conditional strategy, bourgeois prevails (in-between species with higher fitness outcome)

Sensory Exploitation Hypothesis

a hypothesis for bower evolution; males exploit biases that females have in other contexts, such as females being attracted to nest-like material

Producer-Scrounger System

an instantaneous conditional strategy

Patch Foraging Model

deciding how long to forage in an area before giving up (GUT) (usually based on energy gain/time)

Prey Foraging Model

deciding what food to eat given a choice between different types; based on caloric intake, nutrient value, energy expenditure per unit of food, searching, detection, and identification costs, ingestion, digestive costs

Game Theory

when benefits and costs are dependent on the frequency of other strategies that are used; assumes multiple adaptive strategies that compete with one another in a population

Pheromone

chemicals that cause a behavioral response in the same species

• ex: target pheromones from wasps stinging you

Allelochemics

chemicals that cause a behavioral response in a different species

Infochemical

a chemical in the environment that provides information to another organism

allomone

a chemical with a positive impact on the sender, but a negative impact on the receiver (ex: chemical lures; bollus spiders produce a chemical that mimics a moth species to attract male moths to eat)

kairomone

a chemical that negatively impacts the sender, but positively impacts the receiver (ex: when prey smell a predator or vice versa)

necromone

smell of a corpse, whether the same or a different species, which makes an animal change its behavior

Paedomorphosis

retention of juvenile traits in adulthood resembling an ancestral species’ young; evolutionary process; reduction in developmental rate; a phylogenetic evolutionary change in which adults of a later species retain some of the characteristics of juveniles of the ancestral form

Good Genes Hypothesis

a mate choice hypothesis for bowerbird evolution

Giving-Up Time (GUT)

how long it takes an animal to leave a patch forage area

Runaway Selection

preference and trait genetically linked/ cyclical

• a hypothesis for bowerbird evolution

Pleiotropy

when one gene influences two or more seemingly unrelated phenotypic traits

Tonic Immobility

a freeze response, usually a prey responding to a predator to avoid detection

Dear Enemy Hypothesis

the territory is more valuable to the resident because of the cost of settling previous fights with nearby owners (price of finding a new one if you lose)

• payoff asymmetry hypothesis for why residents usually win fights with intruders

Cooperative Signals

receiver and signaler benefit

Uncooperative Signals

only the signaler benefits, not the receiver

Predation Risk Allocation Hypothesis

prey should show the greatest antipredator response in situations with high risk that are brief and infrequent (ex: redtail hawk periodically comes in to hunt squirrels, then leaves); allocate more antipredator effort to high-risk situations and more feeding effort to low-risk situations

Marginal Value Theorem

a forager should sty in a patch until the net gain drops to the mean of all available patches; assumes that animals can instantly assess a patch and remember capture rates of all other patches; generate graphs with tangent to intake curve

Green’s Assessment Rule

an additive rule of thumb for giving up time (GUT)

Optimality Theory

assumption that the attributes of organisms are better than other alternatives in terms of the ratio of fitness benefits to costs; used to measure net fitness gains (benefits minus costs)

• assumes one best adaptive strategy

Six Stages of Predation

1. encounter (within detectable range of predator)

2. detection (identifying prey as distinct objects from background)

3. identification (recognizing prey as profitable/edible and deciding to eat it)

4. approach/attack

5. subjugation (prevent escape)

6. consumption/digestion

Adaptive Antipredator Responses to Encounter

• rarity strategy (prey are uncommon, predators may preferentially feed on common morphs - apostatic, increases cost of search image learning)

• apparent rarity strategy (active when predator isn’t, hide, polymorphism, seasonal changes in color/behavior)

Adaptive Antipredator Responses to Detection

• tonic immobility

• movement mimics sinusoidal pattern of background

• crypsis (reduced signal/noise ratio; ex: camouflage)

• confusion (extreme abundance, polymorphism, random/unpredictable movement)

• sensory limits on perception

Adaptive Antipredator Responses to Identification

• masquerade (resemble inedible objects)

• thanatosis (pretend dead)

• confusion (abundance - hard to target a single individual)

• unpredictable behaviors (disease feigning)

• aposematism (advertise distastefulness)

• Mullerian mimicry (less distasteful resembles more)

• Batesian mimicry (palatable species resembles unpalatable)

• Gilbertian mimicry (palatable species resembles predator)

• honest signaling of unprofitability

Adaptive Antipredator Responses to Approach/Attack

• sustained speed/ sprint to cover

• different locomotor mode than predator

• unpredictable behavior

• redirect attack (tail, not head)

• aggregation (social)

Adaptive Antipredator Responses to Subjugation

• mechanical methods (physical toughness, mucous/slime, autotomy of body parts)

• noxiousness (spines, prickles, jaws, claws, bad taste, toxins, stings)

• lethality

• attract competing predators

• group defense (mobbing)

• resistance to venom

Adaptive Antipredator Responses to Consumption/Digestion

• induce vomiting

• pass through digestive system intact

Difference between crypsis and mimicry?

Crypsis is reduced signal/noise ratio that makes it hard to distinguish prey from the background. It is blending into your environment, while mimicry is resembling another organism, whether another prey or predator species. Both are antipredation strategies, however, crypsis is especially helpful in the detection stage, while mimicry is helpful in the identification stage.

Difference between maypole and avenue-type bower? Adaptive functions?

An avenue bower is made of 2 vertical stick walls separated by a central avenue. A maypole bower is made of sticks woven around a sapling to create a decorated pillar.

Provide females protection from unwanted mating, bower building may indicate a male’s vigor and his quality as a mate (good genes hypothesis), female preferences and male traits evolve together as males with extreme versions of a trait (bower building) have a mating advantage (runaway model), and females or males may be predated during mating and bowers provide protection (predation hypothesis).

Why do domesticated animals have a suite of morphological features in common (e.g. floppy ears, curly tails, piebald coloration etc.)?

They’re experiencing paedomorphosis, a change in the rate of development in a descendant relative to their ancestor. They look, and act, like the juveniles of ancestral species, and many juveniles have similar features.

Why is rarity effective as an antipredator response?

A predator would need to expend energy to establish a new search image. They can much more easily think of one thing to look for than remember other options that are more uncommon just on the off chance they see it. Predators don’t recognize rarer morphs/species as their prey.

What are five ways that being social can enhance antipredator behaviors?

• Approach stage of predation - Prey can make sure there’s at least one animal between themselves and the predator, with increased cover meaning they use another individual as a shield

• Dilution effect - the risk of predation is a function of how many individuals are in the group (oak trees drop tons of acorns, mayflies and cicadas oversaturate predator and are novel)

• Confusion effect - many moving together, the predator can’t detect one individual

• Increased vigilance (many eyes)

• Mobbing behavior - attack and deter predators

What are four ways that being social can enhance foraging (note: avoiding predators isn’t a foraging enhancement, it is an antipredator enhancement).

• acquiring more efficient foraging techniques through learning (watch others, copy their techniques)

• the ability to capture larger or more dangerous prey

• minimize the effectiveness of some prey’s antipredator behaviors (ex: confusion effects)

• social individuals provide information centers (where is the food)

What species can deploy antipredator behaviors after they are eaten?

Vomidir beetles mix chemicals and make bombs in toads’ stomachs to induce vomiting. Some animals (bivalve mollusks, Brahminy blind snakes, soil nematodes, some turbellarian flatworms, rough-skinned newts, ostracods, aquatic leaf beetles, Japanese land snails, etc) pass through the digestive system intact.

Patch Foraging Model

When an animal decides how long to forage in an area before giving up. This is based on energy gain per unit of time.

• ex: How many leatherjacket beetle grubs should a starling pick up before it leaves a feeding area and returns to its nest?

  • Decision assumption: the number of leatherjackets influences the rate of feeding, determining the fledgling survival and body mass

  • Constraints: beak size, travel time, and load

  • Currency: number of leatherjackets per trip in order to maximize the delivery rate

Prey Foraging Model

Deciding what food to eat when given the choice between different types. This is based on caloric intake, nutrient value, energy expenditure per unit of food, costs of searching, detection, an identification, and costs of ingestion and digestion.

• ex: oystercatcher birds determining what size mussel to eat (avoid larger or smaller size classes, prefer medium – normal curve).

Constraints on Foraging Models

• energy (need a certain amount of food or they’ll starve

• rumen (moose have 4 stomachs that can only hold a certain amount)

• sodium (need minimum)

• digestive capacity (max they can eat)

• time (want to minimize time in the open)

Antipredator Responses Available to Embryos

• Red-eyed tree frogs accelerate their hatch rate when exposed to a vibration frequency from wasps – reduce development time to avoid predation from wasps.

• Cuttlefish eggs are transparent. In the presence of predators, embryos move their eyes less. They react more if the predator has eaten cuttlefish.

Psychological Constraints/Biases Preventing Animals from Foraging Optimally

• Time discounting – animals value immediate small rewards more than large, delayed ones. Later isn’t promised.

• Weber’s Law – the perception of differences remains proportional with the increasing magnitude of stimulus. Animals might spend more time foraging in worse patches.

• Subjective perception of time passing – time seems to pass quicker when food is available.

• Memory biases – recent experiences weigh more heavily into decisions than older experiences. Larger payoffs are remembered longer than smaller payoffs.

• State-dependent foraging – risk insensitive (all items valued the same), risk averse (value of next item is less and less), risk prone (every food item is worth more) – how hungry?

Honeybee Information Sharing

Honeybees dance to communicate information about food. A round dance indicates food within 50 meters of the hive. A waggle dance indicates food more than 50 meters away. Waggle dances can also tell you direction to hive based on the angle of a straight run and the sun, the distance from the hive based on the number of times the dance is completed (more = closer) and amounts of sound (more buzzing = closer), and the quality of the food (trophallaxis; faster dancing = better).

Costs and Benefits of Migration

• Costs: energy (cognitive mapping), learning new food sources and predator locations, locomotor, predation (don’t know area’s hiding places or dangerous spots), and increased aggression from territorial conspecifics.

• Benefits: reduced inbreeding, reduced competition (food, mates, resources), and apostatic selection.

Territory vs Home Range

A home range is the area where an animal spends the majority of its time living and seeking food. A territory is the area that an animal will actively defend against intruders to prevent sharing of resources.

Why are side-blotched lizards thought to be playing an evolutionary game of “rock-paper-scissors”? What are some other examples of this game?

Side-blotched lizards have three types: an ultradominant polygynous orange throat, blue throats, and yellow throats. Orange chase and exclude blue, blue mate guard against yellow, yellows take advantage of being ignored by orange. Each morph has an advantage over another, and females prefer the least common morph. A male’s coloration indicates his territoriality and resource holding potential (RHP).

Other examples include male red-shouldered widowbirds having higher RHP with brighter orange coloration and harris sparrows with more black on their heads have higher RHP.

Birds vs Mammals Dispersal Patterns

Birds and mammals differ in which sex disperses. Mammals have more males dispersing and more females remaining at the site. Birds have more females dispersing. Mammal male dispersal may be contributed to by: rearing young being dependent on the presence of natal territory, females have assistance from other mothers defending burrows; females only need one insemination to max out their reproductive success, while males can continuously improve their fitness by inseminating more than one female; competition drives males out. Bird female dispersal may be contributed to by: males defend territories to attract females; females “shop” for the best territory/male; shared parental care is more common, so males can improve offspring survival more frequently. In the last hypothesis, male mammals have less opportunity to improve offspring fitness through parental care because they don’t lactate, which baby mammals need. This is the most widely accepted theory.

What are some reasons for a parabolic gain function when predators move into a new foraging patch? (i.e. resource depression)

Prey are eaten and the patch is depleted. Prey escape or begin hiding after the predator arrives, making capture progressively more difficult. The predator becomes less likely to search new areas within the patch (re-search old areas too frequently). The easy to catch prey are eaten first, the harder ones are eaten last.

When matched for size, why do residents usually win over intruders during territorial disputes?

Residents have more information about the territory (information asymmetry) and know its true value. They have higher RHP and are more experienced in defending the territory (better fighters). The intruder has lower body condition (had to travel and spend energy to locate the territory). Holding the territory improves condition and RHP compared to individuals that lack access to resources. The territory is more valuable to the resident because of the cost of settling previous fights with nearby owners (dear enemy hypothesis, payoff asymmetry hypothesis).

What are the two primary paradigms for the function of communication? What are some of the predictions that should follow based on each paradigm?

To convey accurate information between individuals

• predictions: all signals are inherently honest or evolve to be so, selection favors individuals that ignore dishonest signals, selection favors individuals that are good “lie detectors,” signals should be constructed such that it’s impossible for an animal to give false information, and signals should evolve to be efficient and not convey excessive or redundant information.

To manipulate the behavior of the receiver, such that the signaler benefits

• predictions: all animals will give false information if it benefits them to do so and they can get away with it (lots of lying), some receivers should respond to signals maladaptively, signals should be an accumulation of redundant and even inefficient signals (animals respond to some – commercials), it should result from antagonistic coevolution between the signaler evolving new novel ways to manipulate the receiver and the receiver evolving ways to detect and avoid manipulation by the signaler.

What are some differences in how communication is defined?

Our textbook, Rubenstein 12th edition, defines communication as “the transfer of information from one individual to another that affects current or future behavior and the fitness of one or both individuals.” Other definitions describe it as needing to be adaptive for one party involved and needing to alter behavior, or only changing behavior, or excluding communication with other species. It depends on the discipline the definition came from (ethology vs sociobiology vs behavioral ecology vs neuropsychology).

What is the difference between a signal and a cue? What are some examples of each? What are some examples of intentional and unintentional signals and cooperative and uncooperative ones?

A signal is intentional, while a cue is unintentional. A cooperative signal, where receiver and signaler benefit, would be indicators of male health to females, signals of strength or resource holding potential to a rival, species identification, signals of kin relations, or indicators of submissiveness or dominance. An uncooperative signal, where receivers don’t benefit and signalers do, would be forms of mimicry to avoid predation, false alarm calls, aggressive mimicry, code-breaking (prey lures), allomones (bolas spider pheromone mimics, pitcher plant odors, etc). Intentional signals, those meant to be sent by the signaler, would be courtship signals, territorial displays, aggressive signals, begging and distress calls from young to parents, and most types of lies. Unintentional signals, or cues that aren’t meant to be sent by the signaler or an illegitimate receiver used the signal, would be kairomones, your face turning red while lying, and eavesdropping information.

Interspecific Deception

females of one firefly species drawing males of another in with light flashes prior to eating him; fish with lures attract prey (aggressive mimicry); European cuckoo chicks as brood parasites beg with the same frequency/calls as a nest full of reed warbler chicks; superb fairy wrens co-evolved a counter-strategy to lying cuckoos where they sing to eggs and cuckoos can never learn the song. Others include: burrowing owls mimicking rattle snake sounds (Batesian), margay cats sounding like juvenile tamarin monkeys in distress to attract parents to eat (aggressive), butterfly caterpillars sound like queen ants (aggressive/parasite), and zoodarid spiders smell like queen ants (aggressive).

Intraspecific Deception

fake alarm calls in shrikes chasing the same prey or sparrows feeding at a small food source; fake burying in squirrels; dishonest alarm calls in barn swallows (extrapair copulations); slender crayfish dishonest signaling (males have large chelas unrelated to grip strength but that predict dominance).

How does signal efficacy and signal information content influence the evolution of signal form?

Signal redundancy may be necessary to overcome environmental noise. Attention-getting signals may allow for more efficient transfer of information to prepare the receiver to receive the signal. The added energetic cost of redundant signals, as less efficient mechanisms, may demonstrate their honesty.

Signal information, what’s being transmitted, involves quantity of information, type of information (complexity), veracity of the signal (honest/deceptive), and receiver of information (predator, prey, potential mate, rival, etc).

Signal efficacy is how well a signal is transmitted and how likely it is to be received. It’s impacted by the physical signaling environment, timing and placement of signals, the degree of redundancy in the signal, the sensory channel used, the sensory abilities of the receiver, the neuroprocessing rate of the receiver, and the energetic investment in the signal.

What are some of the important constraints and advantages of different sensory modalities (e.g. hearing, vision, touch etc.)

Chemical sensory channels have a long range, the rate of signal change is slow, the ability to go past obstacles is good, the locatability is variable depending on the environment, and the energetic costs were low, since many chemical signals are already naturally given off.

Auditory sensory channels have a long range, their rate of signal change is fast, the ability to go past obstacles is good, the locatability is medium and dependent upon frequency, the energetic costs are high.

Visual sensory channels have a medium range, the rate of signal change is fast, the ability to go past obstacles is poor, the locatability is high, and the energetic costs are low for static forms (ex: badges) and high for active forms (ex: movement).

Tactile sensory channels have a short range, the rate of signal change is fast, the ability to go past obstacles is poor, the locatability is high, and the energetic costs are low.

What are some specific information about predator risk that a wolf spider can glean from spider silk and excreta? What does it do with this information? What are three different costs associated with wolf spider antipredator responses?

From spider silk, Pardosa can detect the hunger state of Tigrosa, including how hungry Tigrosa is and what it last ate. Using this information, Pardosa starts doing antipredator behaviors, such as freezing and climbing walls. Costs associated with these responses are less foraging time (less likely to go after food), smaller body mass/ reduced body condition, a reduction in egg sac mass and how many individuals are in the egg sac (less offspring), and males take a longer time to engage in courtship behavior (insertion rate of genitalia is lower, miss target area more frequently – distracted by avoiding predator).

Redundancy Multi-Modal Signals

Equivalence is when two signals mean the same thing, and together still mean the same thing, with no intensity change.

• ex: courting male moths Cycnia tenera having similar female responses to pheromones or ultrasonic sounds presented separately or together.

Enhancement is when the intensity of a signal is increased when you use 2 modalities at the same time to convey the same message.

• ex: Aphaenogaster ants recruiting help to carry prey by emitting pheromones, but with larger prey they also stridulate in order to recruit more workers.

Non-Redundancy Multi-Modal Signals

Independence is when the two signals carry different, separate information.

• ex: female Cupiennius spiders have pheromones that elicit localized searching and vibrations that induce courtship displays.

Dominance is when 2 combined different signals result in one signal taking precedence over another.

• ex: dog play displays involve growling and a play bow, with the play bow taking precedence to convey playfulness, rather than aggression.

Modulation is when animals respond to one sensory channel, but not another, but when the two are combined, the response is the non-responsive channel is increased.

• ex: male Alheus heterochaeli shrimp respond aggressively to visual cues alone, such as an open claw, but do not respond to chemical cues alone, but when the two are combined and the pheromone is from a female, male aggressive responses are suppressed.

Emergence is when 2 sensory channels are combined to convey new meaning different from either channel presented separately.

• ex: aromatic pyrazines and red/yellow coloration are associated with noxious insects, alone they mean nothing, but together they create aversion learning.

Features of Ritualized Signals

Signals share information, like quantity, type, veracity, and receiver information. Often related to attracting a mate or acquiring food.

What are some of the sources form which ritualized signals may evolve?*

Preexisting traits in senders or from preexisting biases in receivers. A preexisting trait is a behavioral, physiological, or morphological characteristic that provides informative cues to receivers. This is modified into a signal through ritualization when the sender benefits from the receiver’s response to a cue.

Antagonistic seduction model, which includes pre-existing sensory bias and the signaler evolves traits to exploit sensory bias in another context. It also involves the signaler manipulating the receiver to the signaler’s benefit, selection on receiver to resistance to signal, and selection on signaler to evolve exaggerated signals or a new signal.