PNB Animal Behaviour (Week 9-12)

(New Material)

Why do humans typically prefer slightly salty over unsalted food?

Salt is an essential nutrient that animals have evolved to seek.

How do Gulf toadfish respond to dolphin pops?

They reduce call rate by about 50%.

Describe the result of the benthic and marine stickleback study.

Eda gene is associated with stickleback schooling.

Explain the result of predator study of WT rabbits.

Rabbits did not coevolve with quolls so they have not developed anti predatory responses.

Exercise enhances cognitive performance because it is associated with...

Reduced likelihood of micro-strokes.

Describe the result of the quality patch ant studies.

Ants preferred the dangerous patch when its relative quality was much higher than that of the safe patch.

The best explanation for the observed decline in the relative body mass of great tits in the UK from the 70s to 90s is.

An increase in hawk populations.

Which evolutionary model of mate choice shows mean male rate against mean female mating preference.

Direct benefits.

Males of the P. pustulosus produce a chuck after the whine but males of either P. colardorum or the common ancestor of the 2 spp. do not. Experiments with synthetic calls indicated that female P. colaradorum prefer calls with chucks. This is consistent with the following explanations.

Sensory exploitation.

By definition, females have larger gametes than males. The outcomes of this difference are:

Weaker mate choice and stronger competition for mates in males than females.

The proper legend to the Fig. showing plasma corticosterone level in copperhead snakes is... (low green, high orange, lowest red)

Winners, losers, controls
(Losers highest level)

In sedge warblers, females prefer...

Males with the larger song repertoire

In the western grebe... (in relation to males and female compatibility)

There is a mutual assessment of partners through coordinated movement and food exchange.
NOT MHC compatibility or tail symmetry!

Bystander effect means that...

An observer learns about the fighting abilities of those it has observed.

Results of the artificial selection on eye-span in stalked-eyed flies are consistent with the runaway selection model because...

Selection on eye-span in males altered female preference
(What was available affect female preference which affected length of eye span in males)\#

Are bat's foraging strategy fine-tuned in environment?

1) Suppose two prey items are available, does a bat fly in a way where it can capture the first of these, or does foraging strat take into account a way to get both items?
2) Built a mathematical formula, then let bats forage in arena
3)Found bats tend to fly along paths that took into account both foods
4) Pays off as bats that flew at a trajectory for first prey item were not successful in getting the second

Define search image theory

When animals encounter a prey type more and more, they form a representation of the prey
This representation becomes more and more detailed with experience so the forager becomes more successful

Define optimal foraging theory

A class of mathematical models
Applies optimization theory to predict aspects of animal foraging behaviour within a set of contraints
We exam three models

OFT: What to Eat case
Consider a forager choses between 2 foods
Each prey has energy value, encounter rate, handling time
Prey with highest profit - 1And always taken by forager
If there is only two prey, the optimal diet question is: should prey 2 be taken down? Under conditions?

e1= energy value P1
h1= handling time P1
λ1 = encounter rate with P1
Ts = time to serarch
T = Total = search + handling time
For prey 11) (E= Tsλ1e1)/(T = Ts+Tsλ1h1)

What determines if great tits will take a less profitable prey? OFT Theory

1) Two different sizes of mealworm, controlled rate at which prey was encountered, energy each prey provided, and handling time of prey
2) Used OFT model to predict when birds should take only most profitable prey types and when they should take both
3) Found encounter rate of the most profitable prey that determines whether tits took the least profitable item
4) Same with bluegill fish experiments

Define marginal value theory

How is the marginal value theorem tested in great tits?

1) Calculated optimal time to stay in a patch as a function of travel time
2) Time birds spent in a patch match the optimal time predicted by marginal value theorem

Define risk-sensitive optimal foraging models

Models uses to assess risk in the economic sense
1) Fairly satiated foragers have CONVEX utility function and are risk averse - prefers patches with low vriance
2) Very hungry foragers have CONCAVE utility function, risk prone - prefers high variance patches
3) Forager with LINEAR utility function should be indifferent

How have optimality models been tested in juncos birds? Risk averse/prone

1) Yellow eye juncos are risk sensitive, shifts between risk averse or risk prone depending on energy budget
2) Concave utility function juncos were risk prone, convex were risk averse

Example of species growing food

1) Ants symbiotic relationship with a fungi species
2) Ants used a bacteria that produced antibiotics to kill parasites that grow in their fungal gardens
3) They also meticulously clean parasitic spores

How does group size affect foraging in bluegill sunfish?

1) Bluegill sunfish feed on small aquatic insects that live in dense vegetation
2) Larger foraging groups flush more prey, some prey not eaten by the chasers but by other group members
3) Experiment 300 prey, measured success of fish foraging alone, pairs, and group
4) + relationship between group size and foraging success up until 4 fish

Differences between group size and foraging success of Tai vs Gombe chimps

1) Hunting success + correlate with group size in nonadditive fashion in Tai chimps (more hunter did not increase amt of food by fixed amount, with each new hunter - all group membered received additional food, up to a limit)
2) There are subtle social rules that regulate access to fresh kills, assure hunters that cooperated have a greater foraging success than those that didnt
3) No correlation between group size and hunting success in Gombe chimps, partly bc solo success rate is high

Define public information

Information based on the action of otter's as a cue to changes in environmental conditions

How does public information differ from information acquired from social learning?

1) In social learning, individuals learn something specific (new behaviour, preference of others)
2) In public information models, individuals use the actions of others as a means of assessing the condition of the environment
ex) allows group members to reduce environmental uncertainty

How does public information affect foraging in starling birds?

1) Prediction: Social foragers in poor patches leave patches earlier than solitary individuals
2) Artificial feeding 30 cups either empty or a few seeds, B1 fed from feeder alone or paired with B2
3) Results: B1 left patches earlier when paired than if alone
4) Results: B1 left patches earliest if B2 already had complete information about the patches

What is the relationship between hippocampal volume and caching ability in corvid birds?

1) Hypothesis: Hippocampal region in birds associated with food retrieval
2) Examines four species that rarely cache foods
3) Results: + relationship with food-caching behaviour and hippocampal volume(greater the volume, more food-storing behaviour)

Explain the caching abilities of Alaskan and Coloradan chickadee birds, in relation with hippocampal volume

1) Hypothesis: Natural selection favours better caching and retrieval ability when individuals live in a hard foraging environment
2) Experiment: 15 chickadees, tested on ability to retrieve seeds they cached after 45 days
3) Birds from Alaska (food scarce pop) cached more seeds than Colorado birds (food rich pop)
4) Alaskan birds were more efficient at locating their cached seeds than Colorado birds
5) Alaskan hippocampus weighed less than Coloradan, but had greater volumes!

How does phylogenetic history explain variation in caching ability in corvids?

1) Mapped caching ability (noncachers, moderate, specialized)
Phylogenetic analysis suggests the ancestral trait of caching in corvid is moderate caching
2) Researchers though it would be noncachers
3) Suggests that the simplest variety of a trait is not always the most ancestral variety of that trait

How does proximate factors - birth weight and __ - affect foraging learning in forager honeybees?

1) Forager bees can pair colour, odour, shape, flower topography with sugar rewards - but some foragers learn to pair quicker - why?
2) Weighed new birth bees, tested how much individuals extended its proboscis when exposed to sugar
3) + correlation between birth weight and foraging learning (heavier bees learned better than lighter)
4) Among the heaviest, individuals that extended their proboscis quicker learner faster

How does foraging traditions affect conservations?

1) Killer whales feed on many fishes, but at the individual population level, there is often specialization on some prey - this prey choice is in part determined by social learning
2) BC, CA killer whale pop learned preference for chinook salmon as prey
3) Conservation for this species needs to consider their preference for chinook salmon

Define foraging innovation

Either ingestion of new food type or the use of a new foraging technique

What is the relationship of brain size and foraging technique in various bird groups?

1) In NA and British Isle birds, relative forebrain size + correlation with foraging innovation (Larger forebrain more likely to have incidences of foraging innovation)
2) Graph: forebrain mass:brain stem mass ratio + correlated with relative frequency of foraging innovation
3) Larger the relative brain size -\> increased use to innovative techniques --\> more food intake
4) Larger brain --\> better survival in new environment (invasion potential)

Define flexible stem hypothesis

Proposes that evolvability is likely when members of a clade possess flexible behavioural strategies

Are high rates of foraging innovation associated with high rates of diversification rates in Emberizoidea (superfamily that includes Darwin's finches)

1) Compared to other avian superfamilies, Emberizoideas have high rates of foraging innovation and diversification
2) Probability of using new foraging techniques is a behavioural factor linked to high evolutionary diversification

Is there a role for cultural transmission in foraging behaviour of pigeons?

1) Task for observer pigeons was to pierce the red hand of a red/black paper covering a box
2)
Group 1: Observer birds did not see model on other side of clear partition
Group 2: Observer saw a model eating from a hole in paper
Group 3/4: Observer saw model pierce the red side and get food or no food
3) Results:
G1: (NO MODEL NM) No pigeons learned how to get hidden food, suggest hard to master through individual learning
G2: (BLIND IMITATION BL) Pigeons learned but since the hole was made by experimenters, there was time lag
G3: (LOCAL ENHANCEMENT LE) Did not learn
G4: (OBSERVATIONAL LEARNING OL) Learned real quick

Define producers in pigeon groups

They find food

Define scroungers in pigeon groups

They follow producers and eat what they have found

How do scrounger and producer roles affect foraging in pigeons?

1) Flocks of pigeons allowed to feed tgt, 48 small test tubes, to open - individuals had to learn to peck at the stick in the rubber stopper
2) Results: only 2/16 pigeons learned to open tubes
3) Scroungers followed producers and seem more interested in where producers were rather than what they were doing
4) Removing the two producers, the scroungers didnt know how to open the trait + seemed as if they could open it but opted not to
5) Paired single observer with single demonstrator -- observers rarely learned how to open it themselves

Describe lion roles in relation to their sex.

Know:Females hunt and raise young.Males claim food, have sex, protect their offspring and pride.
Females are driven by gene and instinctually makes sacrifices.Rogue males are ready to take control if male dies.If rogue takes over, likely will kill the old male's offspring.

Why do males and females look different?

1) Natural selection: Differential survival or reproduction of individuals differing in one or more heritable traits.
2) Sexual selection: Differential reproduction due to heritable variation in the ability to obtain mains

Describe the the optimal size of gamete.

Natural evolution has two types of gametes.
Middle gamete size has lower fitness.

What is the size of human egg and sperm

Egg 100umSperm 3um

What is the investment per gamete in females and males.

F: Large, limited by resources so can invest in relatively few gametes
M: Small, can produce many but limited by access to females

What are the two typical outcomes?

Females are choosy.
Males compete with others for access to females.

Describe the bird song practice at dawn.

At dawn, many birds sing.Female fertility at the highest at dawn.No bugs or food yet so birds have time to singListening to calls show who's alive or who's new.Mates are impressed by complexity and originality of songs

Describe repertoire size and pairing in sedge warblers.

Females are faster to choose males with larger repertoires.
When species migrate in spring, males show larger variation in repertoire size. Males that perform less songs have fitness consequence.

Describe muting blackbirds experiment.

Test: Control had sham operations, tests had their syrinx nerves removed.
Result: Muted birds has more intrusions, more fights, more territory loss.

What are three ways animals can avoid their predators?

1) Blending into the environment2) Being quiet3) Choosing safe habitats

What are the three forms of cryptos employed by cuttlefish to blend into the environment?

1) Uniform camouflage against rocks2) Mottled camouflage pattern (small dark spots, like rocks and sand)3) Disruptive camouflage pattern (large light and dark areas to blend with background)

Explain the gulf toadfish and bottlenose dolphin example. (breeding season for toadfish, sounds by dolphins)

Know:- Bottlenose dolphins produce a variety of sounds (clicks and pops) for foraging
Test:- Three sounds played to male toadfish in breeding season (clicks and pops for dolphins, snaps (control) for shrimp)
Result:- Toadfish only lowered their "boat-whistle" call when they heard dolphin whistle+pops and dolphin pops.- Did not lower when they heard dolphin whistles or shrimp snaps

Explain the choice of nesting sites in parrots example and how it affects predation.

Test: Collect data on nesting behaviour and phylogenies from Australian and Amazon parrots
Result: The ancestral state was tree cavity nesting. Nesting in other cavities evolved independently in both location's species
Question: What were the selective forces?
Hypothesis: (1) competition for tree cavity nests was intense, selection pushed species to favour nesting in other cavities, (2) predation on eggs/chicks is high in nesting period, shifting cavities may decrease predation pressure

Describe the anti predator behaviour of wild rabbits example.

Know: Rabbits use odour cues to detect predators
Result: Rabbits decreased use of areas with odour of ferret, fox, cats. But not quolls (despite being native to Australia) because they did not share evolutionary history with it.

Describe the neuroendocrinological changes of rodents when a predator is encountered example.

Test: (1) Mice exposed to odour of predator (2) Exposed to physical stress (3) Expose to neither
Result: Both odour and physical stress increased ACh, serotonin and dopamine. Odour increased greater.
When a drug that reduced anxiety in humans was administered, the increases in responses also decreased in mice.
Neuroendocrinological changes also produced anti predator behaviour; reduced foraging, burying for safety

What are 5 behaviours that prey will use when they encounter a predator?

1) Fleeing2) Approaching a predator to obtain information3) Feigning death4) Signaling to the predator5) Fighting back

Explain how meta-analyses can help ethologist understand anti predator behaviours?

Question: What variables most strongly influenced anti predator behaviour of flight fleeing
Test: Take data from flight initiation behaviour across many taxa
Result: Variables such as degree of cryptos, the distance to a refuge, and the prey's experience with a predator influenced decisions about flight initiation distance

Explain the genetic of schooling behaviour in pelagic and benthic sticklebacks.

Know: Pelagic sticklebacks from open-water experience more predators/schools more tightly than benthic sticklebacks from vegetated environments.
Question: Does variation in the Eda gene affect the variations of schooling behaviour in pelagic vs benthic species?
Test: They insert genetic promoter of pelagic Eda gene into fish from benthic. Mated them to natural benthic fish. Tested schooling behaviour of offspring.
Result: The genetically modified offspring schooled more like the pelagic population than the natural benthic population.

Explain how natural selection can shape fleeing behaviours on the embryos of red-eyed tree frogs.

Know: Red-eyed tree frogs attach their eggs to vegetation that hangs over water. When eggs hatch, tadpoles emerge and drop down into the aquatic habitat. If terrestrial predation is weak, eggs hatch later in the season
Hypothesis: Treefrog eggs will hatch sooner if predation in terrestrial environment is increased. Natural selection will favour embryos that avoid terrestrial predators when predators are at high frequencies
Result: Clutches that were not disturbed by predators hatched in 7 days. Clutches that were attacked hatched at 4-5 days.
Result: Vibrations associated with snake attacks were the cue to shifting habitat away from predators.

What are the 3 non-mutually exclusive benefits of approaching a predator?

1) Decrease the current risk of predation2) Allow gazelles to gather information about a potential threat3) Serve to warn other group members of the potential danger associated with predators

Explain cheetah response to gazelle inspection behvaiour

Results: Cheetahs move farther between rest periods and hunting periods. Causes cheetahs to leave an area sooner than normal, leading to decreased rates of mortality among potential prey.

Explain the adzuki bean beetle anti predator behaviour of feigning death. Explain the first test of long and short duration genetic lines.

Know: Adzuki bean beetle can either fly away or feign death when on a branch, approached by a predator.
Hypothesis: There is a negative genetic correlation between intensity of feigning death and the ability to fly. Beetles that feigned death for a long period would be poorer fliers.
Test: Set up two ways to test ability to feign death and to fly. Death-feigning (DF) treatment measured duration of death feigning.
Two genetic lines were established with DF. Long duration was offspring of female and male that displayed longest death feigning. Short duration was v.v.
Result: Long duration were very poor flyers, v.v. for short-duration
Result: Short duration line had less [dopamine] in their brains

Explain the adzuki bean beetle anti predator behaviour of feigning death. Explain the second test of best flyers and worst flyers genetic lines.

Test: Created best flyers line which were offspring of the best flyers in each generation. Worst flyers was v.v.
Result: Best flyers line displayed good flying skills and short duration of death feigning. V.v for worst flyers

Explain the signalling to predators technique of warning coloration in monarch butterflies

Know: Monarch butterflies contain cardiac glycosides, do not harm the butterflies but aid resistance to infection.
Hypothesis: If prey live in groups, warning coloration could preferentially aid genetic relatives, and thus favoured by natural selection.
Most likely explanation for the evolution of this coloration is that the predator does not always kill the monarch before it senses the toxin

Explain the signalling to predators techniques of tail flagging as a signal in ungulates.

Know: Ungulates flag their tails after a predator has been sighted. Often occurs when predators are at a relatively safe distance from its potential prey
Result: Some white-tailed deers that run fast will flag their tails and use it as a signal to communicate to predators that the fleeing deer will escape the predator.

Explain the chemical defences found in bombardier beetles.

Know: A beetle can discharge its acidic spray twenty times before depletion of supply. Sprays as a mist rather than a jet.
The reservoir contains hydroquanines and hydrogen peroxide and a reaction chamber that holds other catalases
Suggests the possession of these are an ancestral characteristic of chemical defences in bombardiers.

Explain mobbing behaviour in blackbirds.

Know: Blackbirds can mob their predators if they spot one together as a flock. They fly toward the danger, attempting to chase it away.
Question: Is mobbing a form of cultural transmission?
Setup: Naive birds just the friarbird (a novel new species that they hadn't seen before). Model birds saw both friarbird and a little owl.
Test: Model mobs the little owl, but to naive birds, it looks like it mobbed the friarbird.
Result: Naive birds more likely to mob the friarbird, information about danger was transmitted culturally.
The now not naive birds could become models for new naive birds. Found there could be a cultural transmission chain of 6 birds long.

Explain how squirrels alter foraging choices due to predation pressure from red-tailed hawks.

Know: Squirrels either eat their food where they found them or carry it to cover and eat in safety.
The closer the shelter from predation, the more likely squirrels would use the shelter. Squirrels more likely to carry larger items than smaller to safe areas.

Explain the large and small food item test with squirrel foraging.

Models:With no predation, expect squirrels to always take any small food they encounter.
The total handling time associated with larger foods was great enough that Optimal Foraging Models predict larger items should be brought to cover before being eaten.
Hypothesis: In predation, squirrels might sometimes pass up smaller more profitable food items and continue to search for larger morsels to bring back.

Describe crown eagle behaviour.

Large, kills prey 4x its heightPrey: monkeyPredator-prey arms race: monkeys stay away from exposed tree tops, eagles fly among trees, monkeys have special eagle alarm call
Eagle parental care: 4 months in nest, 9 months to independence

Describe the feeding and anti predatory behaviour in ants.

Test: Ants could choose between 2 patches with diet. Higher [ ] patch was either safe or had a predator.
Result:No pred at high [], expect majority of ants thereYes pred at high [], expect ants to be sensitive to presence of predatorsVisits of ants and food taken is lower
Preferred safer patch as long as it was not as low as 8x or 12% worse

Describe the 5 predictions of optimal amount of fat in birds.

Prediction 1: Weights added to starlings would decrease their ascent angle
P2: Starlings on diet have higher ascent angle
P3: +ve correlation between the time to ascend a given vertical height and natural body mass
P4: Starlings housed in aviaries with more protective cover have more fat
P5: WT great tits would have more fat in years with no predators

Describe the optimal amount of fat in birds.

Birds vary fat reserves depending on benefits and costs
More when food less certainLess when predation risk is higher

Describe parasite avoidance in tree frogs.

Know: Snails are intermediate hosts of a trematode parasite
Test: Experiment with comparing egg laying in sites with no snails, low/high infection, low/high snail densities
Result: No eggs landed in infected snailsHigh sensitivity to presence and density of infected/uninfected snails

Explain how bowerbirds build nests to attract their mates.

- Surround nests with many things.- Perform behavioural displays to solicit mating opportunities.- Use optical illusion to place the shells etc in a specific place on the gesso-\> looks larger than they are

Explain how male-male aggressive contests can affects aggression, observation, and gene expression in female cichlid fish

Test: Female in aquarium. Males on each end. Males matched for size and dominance.
Females would see males fight. Measured two genes c-fos and egr-1 in females. Once female chose between the two males, seeing her preferred male win or lose affected gene level.
Result: When females saw their man win, egr-1 and c-fos increased in hypothalamus and hindbrain. Increased in telencephalon when lost.

Define Bateman's principle

1) Females should be choosier than males b/c eggs are expensive to produce and b/c female potential reproductive success is limited
2) Females' choosiness should translate to greater variance in reproductive success of males

Explain how male fruit flies "sing" to females during courtship.

- Singing - vibrating their wings- Pulse song is conspicuous during courtship, the interval between pulses appears to affect female fruit flies- Appear to involve 3 loci that accounts for variance in courtship song

What are the 4 evolutionary models of female mate choice

1) Direct benefits2) Good genes3) Runaway selection4) Sensory exploitation

Describe the direct benefits model.

Hypothesis: Selection favours females that have genetic predisposition to prefer mates that provide them with resources that increase fecundity

Describe the direct benefits model in relation to nuptial gifts.

Know: Nuptial gifts are consumed during courtship. In scorpionflies, males that bring larger prey items are chosen by females.
When gift is in range of 3-19mm2, copulation time increases as gift size increases. Past 19mm2, same copulation time.
Longer copulation time means more sperm is transferred to the female.
Female always terminates copulation.

Describe the good genes model.

Hypothesis: Propose that selection favours that females choose the males with genes best suited to their particular environment.
Females receive "indirect" benefits, such that their offspring receive some of the good genes.

Describe the good genes model in relation to pronghorn antelopes.

Know: Males do not seem to provide females with benefits, and no not actively pursue females to mate. Females visit males that already have harems of females.
Hypothesis: Females use current harem defence as an indicator of good genes in males. Males with larger harems should have offspring that are more likely to survive,
Result: Offspring of males with large harems had higher survival rates than offspring of males with not as large harems.

Describe the good genes model in relation to parasite resistance.

Know: Some males pretend to have good genes. Females should focus on honest indicators of male genetic quality.
Hypothesis: Honest indicator traits should be costly to produce. The more costly the trait, the more difficult to fake.
Females choose males with strong resistance to parasites can receive indirect benefits as they're mating with individuals that have genes that confer parasite resistance.

Describe the good genes model in relation to parasite resistance.
How do females predict which males have the ability, provide example.

Hypothesis: If possessing trait T means males are good at fighting parasites, females can use trait T to judge.
EX: body coloration
Result: Healthy males tend to be colourful, infected are duller. Females often choose the most colourful, least parasitized males.
EX: Peacocks, sticklebacks

Define the major histocompatibility complex.

- MHC is a set of genes involved in disease resistance.- Proteins made by MHC genes guide the body in identifying self vs foreign cells.- It is the most variable set of genes known.

How do females determine which males have MHCs different thant theirs?

- Studies show females use odour to determine whether an individual is a good MHC match.

Explain the test whether humans use MHC when choosing mates.

Test: Men wore a cotton shirt for two nights. Women were given shirts.
Result: Women not on oral contraceptives found odours of shirt different from theirs to be more attractive.
Females like males with dissimilar MHC alleles, but they choose perfumes that magnify their own MHC-mediated odours.

What is the relationship between MHC and disease?

Hypothesis: The most disease-resistant offspring comes from a mate with many MHC alleles.

Explain the MHC counting hypothesis on stickleback fish

Result: When females were given a choice between males, they preferred males with more MHC alleles (up to 8)

How can female sticklebacks assess the number of MHC alleles a male has?

Know: Female sticklebacks can assess the number of MHC alleles by chemical cues.
Hypothesis: More MHC allels = more MHC peptides. Moreover, MHC peptide ligands were the key underlying proximate mechanisms females used.
Test: Females exposed to two water columns. One had male swimming, other was male but supplemented with MHC peptide ligands.
Result: When female+male pair has less than optimal MHC peptide ligands, additional of ligands made the odour in one column more attractive.
Conversely, if a pair already had optimal ligands, addition made the odour less attractive.

What happens to MHC peptide ligand preference in female sticklebacks after giving birth?

Hypothesis: Females avidly forage and raid nests after birth. To avoid eating her own, females should be repelled by the MHC peptide ligand odour she was attracted to prior to mating.
Result: True

Describe the runaway sexual selection model.

Know: Relationship between alleles at two loci. One locus houses alleles that code for female preference and other alleles associated with the male trait females prefer.
Hypothesis: Over evolutionary time, specific alleles from the two genes become associated with e/o.

Describe the runaway sexual selection model in relation to heritable preference for brightly coloured males.

Suppose some proportion of females have heritable colour preference. Suppose degree of male coloration is also heritable.
So there is a group of females who prefer brighter colour and some who don't; and a group of males who are brighter than others.
Females with bright mates should produce bright sons and daughters that genetically coded for preferred brighter males
!!!: Over time, alleles in female that code for preference and alleles in male that code for colour should become linked
This positive feedback loop can "run away" under certain conditions, become increasingly stronger.

Explain stalk-eyed flies and runaway selection.

Know: Female stalk-eyed flies prefer to mate with males with eyes at the end of long eye "stalks". Eye stalk variation is in part due to genetic variation.
Test: (1) Males with largest eye stalks were bred with females. (2) Males with shortest were bred.
Result: Over generations, avg male eye stalk length increased where it was selected for.
There was a positive link between length of male eye stalk ad the female preference for the trait.
Result: Females from the short eyestalk line would prefer shorter eyestalks. As a result of runaway selection??

Describe the sensory bias model.

Hypothesis: When a male trait first emerges, it is preferred by females because it elicits a neurobiological response that is already in place in females. Not associated with mating preference.

Describe the sensory bias model in relation to berries and blue feather songbird species.

Know: Females are able to search out red berries to reproduce.
Hypothesis: Natural selection should favour the neurobiological circuitry in females that tells them to hone in on red items.
Should red feathers suddenly arise in males, red feather birds may be chosen as mates.