Lectures M1-M2 Flashcards
Hamilton relatedness
rB > C
relatedness, benefit, cost
Naked mole rats relatedness and eusociality
- Queen female gives birth to all
- Only mammal that shows eusociality
- Communal care of young
- Reproductive division of labour
- Overlapping generations
Why?
High genetic relatedness
0.81 relatedness
More than any other non-inbred species
Should one kill its sibling - sibling-offspring conflict
Look at rb>c
r=1 for itself, r=0.5 for its sibling (if same father)
- So yes they should fight to survive and kill if need be
- Might also kill them bc it would allow them a better chance of making it to a high weight
How much should a parent invest in their offspring = parent-offspring conflict
- depends on life time cost and benefit
- Consider effect on future offspring and future ability to reproduce
- Offspring may seek more than parents should provide (need to save energy for next offspring) → conflict
Phylogeny
- All living species are a product of descent with modifications from common ancestors
- More related if branch at the same place (same common ancestor)
- More recently related if branched later (closer to the branch tips)
Primates groups (phylogeny)
Primates
- Tarsii
Strepsirrhini
- Platyrrhini
- Catarrhini
Catarrhini
- Cercopithecidae
- Hylobatidae
- Hominidae
Hominidae
- Pongo
- Gorilla
- Pan
- Ardipithecus
- Australopithecus
- Homo
Origins of agriculture - humans
+ definition
Agriculture = planting of certain cultivars in particular substrates
- 10 000 ya in humans
- Cultivation aimed at improving crop growth for food
Insect agriculture
- 50/66 million + years ago in ants and beetles
- involves growing fungi on gardening substrate (e.g. plant material) and protecting their crop from undesired species (weeds and pests)
- use pesticides
- Nine independent origins of insect agriculture, all involving fungal crop
- No reversal to non-agriculture life
1 origin in ants, 2 in termites
Giant asteroid 66 mya
- Caused global mass extinctions and shut down photosynthesis for several months
- Fungi proliferated as they feed on decaying organic matter
- Underground species survived better
- Opportunity for mammals to evolve
Microns and more (measurements)
+ what can we see
1 mm = 10^-3 m
1 micron = 10^-6 m
1 nm = 10^-9 m
- with the naked eye can see down to 0.1 mm
- bacteria and cells 1-30 microns
- viruses 20-100 nm
Learning
- Learning is the ability to acquire a neuronal representation of new information
- An individual may use that information to determine subsequent behaviour
Chemotaxis
- The ability of organisms and cells to move up or down chemical gradients
- Bacteria flows from high to low concentration areas
Chemotaxis in bacteria
- Even organisms with no nervous system modify their behaviour based on experience
- Successive comparison, (better or the same) which requires a minimum of one-step ‘memory’
- Bacteria can only keep the same direction or tumble to randomly change direction
- Simultaneous comparison is impossible because the chemical gradient across the body is too small
Humans chemotaxis gradient
- Do use simultaneous comparison for hearing and seeing, done by nervous system
Simultaneous comparison in humans
Do use simultaneous comparison for hearing and seeing, done by nervous system
Chemotaxis in E. coli
- Detection by receptors
- Conduction by messenger
- Processing based on messenger concentration (‘polling’)
- Transmission of decision
- Response
- flagella direct movement
NOT learning but similar
Sydney Brenner - C. elegans
- A small soil worm (1 mm) that feeds on bacteria, with ~959 cells and 302 neurons, with all synapses mapped & entirely sequenced genome
- Researchers can turn off individual neurons by laser ablation & record from individual neurons
Biomimicry
Copying successful mechanisms of animal behaviour into new gadgets
Innate behaviour
A behavioral pattern that appears in fully functional form from the first time it is performed
(the animal may have not had prior experience with the cues that elicit that behaviour)
- Similar terms: instinct, fixed action pattern, motor program
Example: fly courtship, nest building, blinking
Innate behaviour - advantages
- Saving time when responding to stimuli
- Proper response the first time = making less mistakes
Ex. Village weaverbird
Male chooses a forked branch and builds nest around itself in a specific shape
Goose video
Innate eggs
- All round shaped things=eggs
- Ensures no real eggs are left behind
- Roll any thing near nest and slightly egg like (don’t have to be the right size or shape though)
- Instinct to recover eggs rolled from nest
- Greater benefit to saving all potential eggs than cost of caring for one extra egg
Damselfly experiment
Question: Can damselfly larvae show anti-predatory behaviour to an unknown predator?
- Use damselflies never before exposed to pike (predatory fish), evolved in a habitat with no pike and are inexperienced with pike in the laboratory.
- Let 3 groups of pikes feed on minnows (small fish), damselflies (of the same species) or mealworms (beetle larvae)
Note: minnows co-occur in nature with the damselflies but beetles do not - Move the pikes to different tanks with fresh water and keep them there for 3 days
Damselfly experiment - results
- Damselflies more scared behaviour in tanks with potential predators (reduced activity)
- When they smelled pike + dead damselflies
- Or pike + dead minnows
- NOT pike + mealworms (not familiar with either)
Avoid smell of dead FAMILIAR animals
No innate fear response to unfamiliar ones
NO innate antipredatory response to pike
YES innate antipredatory response to unknown fish that has preyed on damselflies or minnows
NO innate response to unknown fish preying on unknown prey
Insects and blood preferences - background
how many ppl does it infect
- subspecies Ae aegypti that is brown and gets meals from humans = domestic species
- infects 400 million ppl / year
- spreads dengue fever, etc.
- accidentally introduced into Kenya in 1950s
- they would lay eggs in water containers
Insects and blood preferences - explanation
Due to odour preferences
- Subspecies don’t breed with one-another even though they live close and CAN produce viable offspring
- Genetic differences in odorant receptors (family of chemosensory receptors) in their response to sulcatone
- Sulcatone found in human odorants much more than in nonhumans
- Domestic subspecies much more sensitive to presence of sulcatone and OR genes for sulcatone overexpressed (= more functional products) in domestics
= odour preferences
Termite Eusociality
- When queen dies, some workers become aggressive until one of them become queen
- Due to lack of queen-worker chemical signalling
Specifically from gene Neofem2 - begin to do aggressive butting that would eventually lead to reproduction
Mendel’s Laws
First Law: Principle of segregation
- Individuals have two copies of each gene (aka “factors”) that remain separate and segregate/distribute during formation of eggs or sperm
- Can be dominant or recessive
Second Law: Independent assortment
- Whichever allele is passed down to the next generation at one locus is independent of the gene passed down at the other locus
- Only true for unlinked loci
Mating behaviour of male ruff birds - Philomachus pugnax
Satellite or independent type ruff males
- Independent → majority of males, guard small mating territories
- Satellite → minority of males, temporarily share territories with independents, form an alliance where they both court females, don’t defend their own territories, smaller and lighter plumage than independents
Mating types controlled by a single gene; S for satellite
- Independents = ss, satellites = Ss or SS
- Independent still more common due to historical distributions over time
Genes for polygenic traits
- Traits associated with variation at more than one locus = polygenic
- Set of genes, each contributes to a small amount to the expression of the trait of interest
- Search for the set = looking for QTLs (quantitative trait loci)
QTL mapping
- Find general region in a genome where quantitative loci reside
- Use a marker loci with an unrelated function
- If usually inherited together = genes near each other
QTL mapping and fear/fearlessness in mice → Jonathan Flint
- Studied fear and anxiety by measuring open-field behaviour in mice
- Fear/anxiety when high defecation and low activity
- Identified more fearful mice and determined QTLs for fear on six chromosomes; 1, 4, 12, 15, 17, 18
Genes, mRNA, and honeybee foraging
Per
- Period/per gene influences circadian rhythms and development time in fruit flies
- Per mRNA influences developmental changes associated with the transition to forager
Older + foragers = more per
Younger + nurses = less per
link between per mRNA and foraging rather than mRNA and development
Honeybee gene malvolio - implications for foraging
- Mvl determined to be useful as it affects the way fruit flies respond to sucrose, which is n honeybee food and drink
- Most to least responsiveness to sucrose: pollen foragers, nectar foragers, nurses
- Both the amount of manganese in the head of a honeybee and the amount of mvl mRNA in the honeybee brain were high in pollen foragers and nectar foragers, and low in nurses
Song acquisition in birds
F N Z
FOXP2 gene: associated with song perception in birds
Deactivation in young zebra finches = impaired ability to copy songs
Neostriatum section of the forebrain: associated with song pattern recognition, song discrimination, and the processing of auditory cues in birds
Hearing zebra finch songs = zenk gene mRNA levels increased = increase in the number of neurons in the neostriatum
Zenk gene: plays a role in zebra finch birdsong
exposed to the song of another species = reduced zenk mRNA response
Habituation: if a zebra finch is exposed to the same conspecific song repeatedly, mRNA levels return to baseline
Suggests: after repeated exposure, a zebra finch categorizes a song as familiar, so it no longer expresses zenk
Vole sociality - avpr1a (and vasopressin) experiment
- Avpr1a gene controls vasopressin receptors
- Long-version Avpr1a allele: associated with prosocial behaviours (parental care + affiliative interactions with mates)
Compared homozygous for long version of the allele and homozygous for the short version of the allele
- If avpr1a primarily responsible for male behaviours toward mates and offspring, then two lines should have different suites of social behaviour
= true
- Longer version homo males had more pup licking and grooming, also responded more positively towards familiar females
Great tits genomics experiment
Fox and mutations
Cognitively sophisticated strategies with respect to foraging and mate choice
Now used as a model system
Their entire genome sequenced
Background:
- Synonymous mutations = no effect on fitness
- Nonsynonymous mutations = fitness consequences
Experiment:
- Collected genomic data from different great tit populations
- Determine strength of natural selection at a locus: calculate the ratio of nonsynonymous to synonymous substitutions
- Higher ratio = likely that positive natural selection has occurred
Results:
- Genes linked to cognition were overrepresented in areas of the genome that showed evidence for positive natural selection
- Selection was strong on the FOXP2 gene
Conclusion: suggests that natural selection has favoured a suite of genes associated with cognitive functions linked to survival and reproduction in great tits
Territoriality in micro, sticklebacks, bees
Question: are there shared “genetic toolkits” employed in similar suites of behavior seen in widely divergent species?
Experiment: examined the behavioural response to territory intrusion in house mice, three-spined sticklebacks, and honeybees + sequenced mRNA from the brains of each
Results:
- House mice, three-spined sticklebacks, and honeybees share a genetic toolkit that includes G-protein-coupled receptors linked to territoriality.
- All species show similar patterns of gene expression with respect to a number of genes likely important in territoriality
Conclusion: Deeply conserved clusters of genes + deeply conserved gene expression patterns may help explain similar behavior in phylogenetically distant species
Tinbergen development
Examples
- In “on the aims and methods of ethology” Niko Tinbergen talks about how development is important to help shape an animal’s behaviour
“Development” including:
- In-utero effects
- Specific effects of environmental factors throughout an individual’s life
- Environmental factors including both biotic and abiotic factors
Development, Dispersal, and Climate Change - spiders
Numerous dispersal strategies, use environmental cues to choose which one to use
In spiders: E. Atra
- Rappelling or ballooning behaviour
Ballooning:
- Use silk threads to sail long distances - hundreds of yards
Rappelling:
- Use silk thread to create a bridge for short distance dispersals
- Use short distance rappelling during spring migrations when potential territories are abundant and less risky (crop land with abundance of habitats)
- Use long distance ballooning during fall migration when the chances of getting a suitable habitat close by others is small enough that ballooning to distances far away may be worth the costs of having little control where a landing will occur
- Use temperature as a cue of which strategy to pick - proven by controlled temp experiments
Development, Temperature, and Ovipositing Behavior in Parasite Wasps
Background:
temperature has strong effects on olfactory senses in insects = fitness effects
Parasitoid wasps lay eggs inside a host species, and adult females avoid hosts that have been parasitized
Question: would temperature that female larvae were exposed to during development affect their ability to learn how to find suitable hosts for laying eggs?
Experiment:
Raised female larvae in 4o C for either three weeks or twelve weeks + a control, then raised them at a normal temperature
Testing: presented females with three different patches that differed in the number of good hosts unparasitized/parasitized hosts
Results: exposure to cold during development affected:
Number of eggs a female laid inside a host
Female’s ability to discriminate among hosts of different quality: became worse at discriminating hosts using external cues on the host after it had been parasitized
Family Structure, Development, and Behavior in Prairie Voles
Significant variation in family structure
- ⅓ of pups raised by mother, ⅓ by mother and father, ⅓ by communal nest including their father and mother and others
- Looked at single mother category (SM) versus both parents (BP = biparental) and eventual parental behaviour of those offspring
- SM group pups left alone more often than BP group
- BP group received more grooming and licking
- Same amount from mothers in each group, just less overall in SM due to lack of father
Now adult offspring parental behaviour
- Raised in SM females = licked and groomed their pups less
- Raised in SM females and males = took longer to find a mate and bond with their mate than BP group
Early Nest Development and Behavior in Cichlid Fish: helpers
Background: In Cichlid fish, young in nests are raised by adults + older sibling “helpers”, both of them defend the nest and remove parasites from eggs and developing fry
Hypothesis: presence of both parents + helpers may provide young with behavioural skills that are beneficial in a species that lives in complex social groups, by:
Freeing up time for developing offspring to interact with others, rather than to be vigilant for predators
Serving as role models for the developing offspring, which could copy their actions
Experiment: raised newly born fish in groups together in different treatments:
- No adults present
- Adult male + female present
- Adult male + adult female + helpers-at-the-nest were present
Results: Fish raised with adults or adults + helpers displayed behaviours that were less costly in terms of energy but still very effective in defending their territories
Conclusion: Early environments experienced by Cichlid fish had important consequences for behavioural decisions later in life
Early Development and Its Effect on Parental Behavior in the Oldfield Mouse:Sibling nest helpers
Background:
Successful parental behaviour = the more offspring you raise (direct experience) + developmental factors early in life
Some female oldfield mice remain at the nest and help their mothers raise young
Question: Do females that remained at the nest during the rearing of their younger siblings become better mothers to their own offspring?
Experiment: Experimentally created inexperienced and experienced female oldfield mice by removing (or not removing) females from their natal nests
Results:
All females: became better parents as they produced more and more litters
IF females: built nests later + nests were not as good as those of EF
EF females: superior nest-building behavior = litters had a higher chance of survival
Conclusion: the developmental experience of being present when one’s mother raises offspring has long-term consequences for parenting abilities
Define habituation and sensitization
Habituation: A decrease in response to a stimulus after repeated exposure.
Sensitization: An increase in response to a stimulus after repeated exposure.
Explain the process of classical conditioning using the eye blink reflex
An air puff (US) to the eye causes an automatic blink (UR).
○ A tone (CS) is repeatedly paired with the air puff.
○ Eventually, the tone alone (CS) elicits a blink (CR).
What is extinction in classical conditioning?
The weakening and eventual disappearance of the conditioned response (CR) when the conditioned stimulus (CS) is repeatedly presented without the unconditioned stimulus (US)
Why are critical tests for associative learning needed?
To verify that changes in behaviour are due to associative learning and not other factors
Describe the three conditions used in critical tests for associative learning.
○ CS predicts US: Strong association, likely to result in associative learning.
○ Random control: No association, unlikely to result in associative learning.
○ CS predicts no US: The CS predicts the absence of the US, may result in inhibitory conditioning.
Associative learning and classical conditioning relationship
Basically the same
Associative learning occurs only when? Why?
Associative learning occurs only when: presentation of the CS is associated with increased probability of the US
- Animals have innate predispositions for associating certain stimuli (CS) with certain states (US)
- Animals consider both their prior knowledge and current experience to infer what relationships are likely to occur
- Posterior knowledge = some function of prior knowledge & new evidence
What is Bayes’ Theorem? - explanation
A mathematical formula that helps us understand how posterior probability relates to prior probability
Kinda like a ratio or a percent in probability?
Bayes’ Theorem - equation
DON’T MEMORIZE
P (H1⼁E) =
[P (E⼁H1) x P(H1)]
/ [(P (E⼁H1) x P(H1)
+ P (E⼁H2) x P(H2)]
P (H1⼁E): posterior prob. for H1 given evidence
P (H1): prior prob. for H1 before any event
P (H2): prior prob. for H2 before any event
P (E⼁H1): prob. for evidence given that H1 is true
P (E⼁H2): prob. for evidence given that H2 is true
Bayes’ Theorem what is a proof
Change prior probabilities and redo the calculation
(ex. general probability of HIV test positive vs. probability of positive for a high-risk patient)
How does Bayes’ Theorem apply to animal behaviour?
Animals use Bayesian-like computations to make decisions in uncertain and variable environments.
They combine prior knowledge and new evidence to update their beliefs and adjust their behaviour.
Bayesian inference about the cause of illness
The prior probability of novel food being the cause of illness is much higher than that of noise, so animals are innately tuned to the possible association between taste and food-poisoning
- (we have innate biases that are similar to the ones we get from bayes)
Variation + uncertainty examples
Variation: Food, predation risk, competitors, mates
Uncertainty: Food to last the night/winter, surviving to the next breeding season, winning the next fight for food/safe feeding location/females, mating for males, successful reproduction for females
Coping with variation + uncertainty
Variation:
- Learning/sampling
- Accepting variation + being prepared to deal with it
Uncertainty:
- Body fat
15-30% of body weight = 2 months no food
- Caution
- Alertness
- Learning
- Sharing (food, defence etc.)
- Forecast (air pressure)
- Insurance (humans)
What is the Rescorla-Wagner model?
When a CS and US are paired, the change in the strength of their association (ΔVt), changes proportionally to the learning rate (α), the difference between the maximum strength possible (λ), and the current strength (V)
Discrete Rescorla-Wagner equation
Vt+1
= Vt + ΔVt
= αλ + (1-α)Vt
What are the weaknesses of traditional approaches to studying learning?
They often rely on artificial laboratory settings, may not reflect natural behaviour, and ignore cognitive processes.
What is anticipatory conditioning?
A type of learning where animals associate cues with events and adjust physiologically in anticipation of those events.
Ex. humans may experience less intoxication from a familiar alcoholic beverage (fav. beer) than an unfamiliar drink (green peppermint) due to anticipatory physiological responses.
Coffee mix up results
When drank oj with same amount of caffeine
- drinking caffeinated drink not previously associated with caffeine will result in stronger effects of caffeine compared with the effects of drinking familiar coffee
- bc no physiological prep
When drank decaf
- Unknowingly drinking decaf in your regular coffee mug and regular time = headache
- Might still feel more alert = placebo
How does skipping regular morning coffee cause headache?
- Caffeine causes constriction of blood vessels in the brain
- Physiological adaptation to caffeine involves relaxation of cerebral blood vessels to counteract caffeine effect
- Skipping regular morning coffee thus = headache
Do all animals do social learning
NO
There is either no or limited social learning in many animal species
- it’s important when there is some
- we study it bc we also do social learning
Bumblebee wasp - no social learning
Both sexes show individual learning:
- Each individual is on its own: there is neither social interactions (just male fighting) nor social learning
- This is typical to most animals
2 (probably) social learning anecdotes
Potato washing in monkeys:
- Imo the monkey (Japanese macaque) was the first individual who washed potatoes to remove sand
- Other monkeys started to do the same later
- Is it social learning? Cultural transmission
Milk-bottle opening by blue tits:
- Blue tits learned to peck the top of the bottle and get the cream
Graph:
- The behaviour was first observed in England in the 1920’s and spread rapidly among blue tits
- Some kind of social interaction was probably involved because of the rapid spread…
- There is no empirical evidence for either social learning in general or imitation in particular in this case
Weakness of probable social learning anecdotes
They are not controlled experiments, (but inspire such experiments)
Social learning
learning from others
Information
anything that reduces uncertainty
Private vs public information
Private information: inaccessible to others
Non-private information = social information:
- just by being somewhere or doing something, you unintentionally/inadvertently provide info
- Social info is vicariously acquired (vicarious = substituted for experience)
Two types of social information
Cues: Inadvertent social information (ISI). Unintentionally providing information because other people are at that place or doing that thing.
Public info OR location cues
Signals: Intentionally communicated information
- ex. signs
3 benefits of social (vs individual) learning
- Social learning can be much faster + safer than individual learning because one can avoid much of the trial and error that accompanies individual learning
- Social learning across generations prevents the loss of information upon an individual’s death
- A rare individual’s insight can spread rapidly within populations and across generations
Simple types of social interactions (2)
- Local enhancement: Observers are more likely to be drawn to a particular location of the environment because a model was performing some action there
- Social facilitation:
The mere presence of a model, regardless of what it does, makes observers more likely to do something
- No explicit social learning
- No learning (i.e. no new info represented in memory) or imitation
Examples of social enhancement/facilitation in humans
- We laugh when others laugh
- We go to places where others go
Social facilitation:
- if there’s a red light and someone starts crossing, others are likely to start crossing too
- Toilet paper shortage. Others started buying toilet paper, so we did too
- We yawn when someone near us yawns
Examples of social enhancement/facilitation in conservation
- Attract endangered birds to a restored or protected habitat by putting decoys there, so more birds will join
Simple social learning - rats smelling others experiment
Observer smelled model rat with either:
Powdered with a smelly compound like cocoa or cinnamon
1. Powdered face
2. Surrogate (plastic)
3. Dead powdered face
4. Powdered rear
only the live rat + powder generated social learning
whenever carbon disulfide (CS2) was provided with a novel odour to the observer, learning occurred if…
CS2 alone: learning
Water: no learning
Also did an exp. where: - Students in the lab breathed next to observer rats with novel odours
- Observers learned from human demonstrators
Simple social learning in black rats - Learning how to eat pine seeds
Imitation or no
Two techniques for seed removal:
1. Spiral technique: most efficient way to remove seeds is to start from the base of the cone and remove the scales in a spiral upward fashion
2. Shaving technique: slower, energetically demanding, not efficient
Social learning YES
- Only 3% of adult rats inexperienced with pinecones learned to use the spiral method in the presence of experienced rats
- All adult rats reared by parents using the spiral method used that technique
- 70% of rats learned the spiral method in the presence of cones partially striped in the proper fashion = no evidence for imitation
Mother-offspring social learning: Rat pups are exposed to partially open cones while feeding with their mother, so they pick up this method quickly
Mother-offspring social learning in cats and cheetah
Cat mothers provide “processed” prey to kittens: first give them dead mice, then gradually start giving them less dead mice
The mothers gradually increase the difficulty of the kitten’s task: provides learning opportunities to the young kitten
Is this imitation or teaching? No
Video: Peregrine falcon play
- Hunting speed of 320 km/h
- Successful parents must hunt several times a day to feed offspring
Adaptive value of play: learning complex skills
- Parents provide learning opportunities = simple social learning (neither imitation nor teaching)
Meadow voles brains
- Polygynous
- Males have larger territories than females, outperform them on spatial memory tasks, larger hippocampus (linked to spatial learning)
- Selection acted differently based on sexes
Cowbirds brains
- Females have larger territories than males due to obligate nest parasitism = lay eggs in nests of other species
- Spend time and energy locating others nests, laying their own eggs there, kicking other bird out
- Very demanding in terms of spatial memory = selection should have favoured better spatial memory in females
Individual learning → Three questions
How do animals learn?
Why do animals learn?
What do animals learn?
Learning
how long do behavioural changes last
relatively permanent change change in behaviour as a result of experience
Issue: how long is relatively permanent
Phenotype
observable characteristics of an organism
Phenotypic plasticity
ability of an organism to produce different phenotypes depending on environmental conditions
Bryozoa - phenotypic plasticity
- Invertebrates that live in colonies
- Lack spines (predator defence) if they develop in the absence of predators
- Grow spines quickly when exposed to predator cues
= phenotypic plasticity due to environmental changes of introduction of predators
Learning / phenotypic plasticity relationship
Learning is a type of phenotypic plasticity
Not all phenotypic plasticity involves learning
Painted redstart (birds) flushing behaviour - experiment phenotypic plasticity
- Move tails and wings to flush insects from the overhanging branches
- Either due to learning that when they flap wings under branches they get food, OR a fixed genetic response (not learned)
Experiment:
- Will birds flush in lab conditions when there is no reward (no bugs that fall)?
Result:
Yes they still flushed = behaviour not a result of learning
- Instead is a result of only phenotypic plasticity (whether under trees or not)
3 experiences that lead to learning
- Single-stimulus
- Stimulus-stimulus
- classical conditioning - Response-reinforcer
- instrumental conditioning
Rat blue stick - single-stimulus recording
Put an arbitrary cue = blue stick in the rat’s cage a few times a day
- If they begin to turn their head towards it = sensitization
- If they become less likely to turn their head = habituation
Explain the difference between habituation and sensitization
Habituation: Decreased response to a repeated stimulus.
Sensitization: Increased response to a repeated stimulus.
Issues with habituation
- hard to teach new significance for something that has been habituated
- Can become a problem if in experiments predators can’t actually cause harm so they get habituated
- also a problem for animals trained in captivity to be released back into the wild
Pavlov classical conditioning = stimulus-stimulus learning
○
Unconditioned stimulus (US): Stimulus that elicits an innate response (UR).
○
Conditioned stimulus (CS): Initially neutral stimulus that, after pairing with the US, elicits a learned response (CR).
○
Unconditioned response (UR): Innate response to the US.
○
Conditioned response (CR): Learned response to the CS.
Differentiate between appetitive and aversive stimuli
○
Appetitive stimulus: Pleasant or rewarding stimulus (e.g., food, mate).
○
Aversive stimulus: Unpleasant stimulus (e.g., shock, predator).
Explain excitatory and inhibitory conditioning
○
Excitatory conditioning: The CS predicts the presence of the US.
Positive relationship
○
Inhibitory conditioning: The CS predicts the absence of the US.
Negative relationship
What is second-order conditioning?
A new CS is paired with an already established CS, leading to the new CS eliciting the CR.
New CS presented BEFORE old one
Describe the three types of learnability: overshadowing, blocking, and latent inhibition
○
Overshadowing: A more salient CS overshadows a less salient CS when presented together.
- no prior association
○
Blocking: Prior conditioning with one CS blocks conditioning with a new CS presented simultaneously.
- yes prior association
○
Latent inhibition: Previous exposure to a neutral stimulus makes it harder to later condition that stimulus.
Instrumental (operant) conditioning
- Response-reinforcer
Behaviour is modified through reinforcement (increasing behaviour) or punishment (decreasing behaviour). Animals learn to associate their actions with consequences.
State Thorndike’s Law of Effect
Pos vs neg response impact
If a response in the presence of a stimulus is followed by a positive event, the association between the stimulus and response is strengthened. The opposite is true for negative events.
Why do animals learn from an evolutionary perspective?
Learning allows animals to adapt to changing environments and improve their chances of survival and reproduction.
Thorndike + Pavlov + Skinner + Harlow idea of learning
Qualitative features of learning are the same in all animals
= all animals learn in a fundamentally similar fashion
BUT we think this is unlikely due to different evolutional paths
What is the ecological learning/cognitive ecology model?
A model proposing that learning abilities evolve in response to specific environmental pressures and the predictability of environmental cues.
Garcia’s rat water experiment
Stimuli that made rats ill were easily paired with tasty water (gustatory cue), but not with bright-noisy (audiovisual) cues
Painful stimuli were easily paired with bright-noisy water (audiovisual cue), but not tasty water (gustatory cue)
Learning occurred without immediate reinforcement
Garcia’s rat water experiment - natural selection relevance
Natural selection favours the ability to pair gustatory cues with getting ill
- b/c internal discomfort in nature is likely due to consuming something bad
Natural selection favours the ability to pair audiovisual cues with peripheral pain
- b/c peripheral pain in nature is likely due to hearing a threat
Fruit fly quinine experiment - nat. selec. and associative learning
colour or odour
Quinine = a chemical flies are adverse to
In each generation, only eggs laid in the location with the reliable cue were selected (either colour or odour reliable at indicating quinine)
Significance: selection pressures can change the nature of associative learning
How can population comparisons shed light on the evolution of learning?
By comparing learning abilities across populations living in different environments, researchers can identify how natural selection has shaped learning in response to specific ecological challenges.
Dove population comparisons
Group vs solitary
Question: Do individuals that live in groups (and must compete with group-mates for resources) have better learning skills than individuals that are more solitary?
Results: Group-living doves outperformed individuals from solitary-living doves on a learning-related foraging task
Stickleback antipredator behaviour
Environment / setting raised in
Question: Does natural selection act more strongly on antipredator strategies such as learning about danger in sticklebacks from predator-rich populations?
Experiment: Raised sticklebacks from predator-rich streams and predator-free streams in the lab + they had no interactions with predators during development
Results: Fish from high-predation populations learned to avoid an area associated with predation (and food) more quickly than fish from low predation areas
What do these results mean?
Natural selection has operated on learning and antipredator behaviour in these populations of sticklebacks
Cost of learning 1/2 = reduced survival in flies
Learning Group:
These flies went through five trials pairing an odor with a shock (a learning task). This was the group that has been selected for 50 gens. to have better learning abilities.
Results: The learning treatment died 9 hours sooner than the other fruit flies from same line of females
Suggests: tradeoff between long life and learning
Cost of learning 2/2 = reduced fertility in butterflies
Background: cabbage white butterflies lay eggs on green plants, and show an innate preference for searching for green, but there is genetic variation in the extent to which individual butterflies can be trained to search for red items
Results:
1. Constitutive cost: females from families with individuals who best learned to forage for red items (good capacity) = fewer and less well developed eggs (likely due to the investment in larger brains)
- Induced cost: females from families selected for the ability to learn to forage red items = greater decrease in reproductive success after learning
Two different types of costs to learning
Constitutive: are paid by good learners, regardless of whether they learn some task
Induced: are paid only when learning has occurred
Under what environmental conditions is learning favored over fixed genetic rules?
Learning is favored when:
○ Predictability within an individual’s lifetime is high.
○ The association between cues and environmental features changes every generation.
Fixed genetic rule is favoured when
- Environment rarely changes within-lifetime AND between generations:
- so the environment that offspring encounter is similar to that of their parents. information is best passed on by a fixed genetic rule, since such a means of transmission avoids the costs of learning. - Environment is frequently changing within a lifetime:
- if the environment is constantly changing, learning is worthless because what is learned has no predictive value, making it completely irrelevant in the next situation. Thus, genetic transmission of a fixed response is favoured simply because it avoids the cost of learning
How can learning be applied to conservation efforts, such as reintroduction programs? - hellbender salamanders
Hellbender salamanders: have an innate fear response when exposed to an alarm chemical produced by other hellbenders
Experiment: classical conditioning protocol in which there were two treatment groups trained to:
Pair alarm chemical + scent of brown trout (predator)
Pair alarm chemical + water (control)
Results: those that paired the alarm chemical + predator showed more fine-tuned antipredator behaviours in response to trout
Conclusion: Individuals trained to show fear responses when exposed to real predator cues would be more likely to take action to avoid the danger and therefore survive when encountering predators in nature for the first time
Damselfly experiment
Question: Can damselfly larvae learn about the potential dangers associated with pike encounters by using chemical cues?
Damselfly larvae were exposed to the water containing either chemical cues from:
Tank water of pike + mealworms (control)
Tank water of pike + minnows (co-occurring, also eaten by pike)
Tank water of pike + damselflies (same species, also eaten by pike)
Results: larvae reduced foraging behaviour in response to the water where pikes preyed on minnows/damselflies, but not mealworms.
What do these results mean? because damselflies co-exist with minnows, but the damselflies had no prior experiences with pike, these results suggest that damselflies innately associate the scent of pike + damselfly/minnow with danger, but they make no association between pike, mealworm, and danger, so no evidence of learning (they simply were predisposed to respond to the smell of pike and prey as dangerous)
Damselflies exposed to pike + minnows/damselflies in the first experiment did show anti predatory behaviour when exposed to the scent of pike + mealworm (decreased foraging activities) = they learned :)
Damselflies exposed to pike + mealworms in the first experiment did not decrease their foraging = they did not learn :(
Learning about their mate
When parental investment is shared → difference in ability to learn about pairmates between sexes is small
Sex differences in parental investment → sex differences in their learning abilities when selecting mates
The one providing more resources is a more valuable resource to opposite sex, so we expect the opposite sex to be under strong selection pressure to find a good mate
If only females provide resources for offspring → males should be better at learning about the location/abilities of mates than females bc females more valuable
Learning about Familial Relationships - tits churr example
Background: Young long-tailed tits often become helpers at the nests of their close genetic relatives, where they gain indirect fitness benefits by contributing to the survival of their close genetic kin
Question: How do the birds know who is kin?
Answer: Those raised together will have the same churr calls, whether they are genetically related OR NOT
- investigated using cross-fostering
= learning calls was relevant
Learning about Aggression - paper wasp facial learning
Experiment: Paper wasps were exposed to facial images paired up with aversive stimuli to determine whether they were capable of facial learning.
Results:
Paper wasps displayed facial learning even when antennae were messed up (paired shock with specific facial image), but only when images used in the trials mimicked actual paper wasp faces
- Wasps did not display learning for geometric patterns or caterpillars
What do the results mean?
Natural selection may have favoured conspecific facial learning (avoidance learning) in paper wasps because it allows them to recognize individuals in their colony, reproduce, etc.
Molecular Genetics of Learning in Rats - anxiety and shock avoidance
Background:
Two lines of rats descended from a single population:
1. Syracuse High Avoidance (SHA) line:
- Artificially selected for high shock avoidance
- Less anxious
- Better at learning to avoid aversive cues
- Syracuse Low Avoidance (SLA) line:
- Artificially selected for poor shock avoidance
- More anxious
- Poor at learning to avoid aversive cues
Experiment: Examined gene expression patterns in the hippocampus (important in avoidance learning + anxiety)
What do the results mean?
Complex traits like avoidance learning may be controlled by many genes, each of which contributes a small amount to phenotypic expression
Endocrinology of Learning in Rats - anxiety and glucocorticoids
Background: Glucocorticoid (e.g. corticosterone) hormones:
- Role in: stress responses (emotional state) + learning (cognitive abilities)
- Bind to: receptors in the hippocampus
Experiment: Classified rats as either high-anxiety (HA) or low-anxiety (LA), then tested on their spatial learning skills. Placed rats in a water maze and measured their abilities to find and remember the location of a submerged escape platform on which they could rest
Results:
HA rats:
- took longer to learn to swim to the submerged platforms because they spent more time swimming close to the edge of the water tank (poor learning)
- higher corticosterone levels after the water maze
- fewer mineralocorticoid receptors in hippocampus = reduced ability to bind corticosterone = increase in circulating stress hormones
LA rats:
- found the submerged platforms faster
- lower corticosterone levels after the water maze
- more mineralocorticoid receptors in hippocampus
What do the results mean? Cause-and-effect relationship is unclear here, but the results suggest a link between stress hormones, stress hormone receptors, anxiety, and learning.
Anthropomorphism
The attribution of human traits to non-human animals
Imitation
New response or something you were able to do before
an observer learns a new behaviour by watching a demonstrator
the acquisition of a topographically novel response through observation of a demonstrator making that response (the behaviour must lead to the achievement of some goal)
Neither the presence of a demonstrator nor some outcome of the behaviour are sufficient (e.g. odour, open cones, wounded prey)
- The majority of animals just do not do it
- We can easily do it
How does one know how to imitate
How does the observer’s motor system ‘know’ which muscle activation will lead to the observed model’s movement?
Mirror neurons in the premotor cortex F5 are active both when an observer observes & executes an action
Quail imitation experiment
Imitation treatment: demonstration of a novel behaviour that could be mimicked
- 5 observers watched a demonstrator pushing the screen to the left with its beak to gain access to food
- same but to the right
Control: (cannot be imitation because observer did not see the demonstrator do it)
M (matched) = observer did the same thing as the demonstrator
NM (non-matched) = observer did not do what demonstrator did
More matched behaviour was seen in the imitation trials (=imitation)
Most recent ancestors to homo
Chimpanzees/pan are our closest living relatives → most recent splitting
Ape noun vs. verb
Ape (n) = Hominidae (& lesser primates)
Ape (v) = imitate
Imitation in chimps - poking experiment
Task: open a Plexiglas box to get fruit
Demonstration:
- Half subjects observed a demonstrator poking 2 plastic rods & then lifting the lid
- Half observed the demonstrator twisting clockwise and pulling the plastic rods & then lifting the lid
Different techniques so they’re sure it’s not local enhancement
Observers would employed the technique they have observed to open the box
Requirements for teaching
- A ‘teacher’ modifies its behaviour only in the presence of a naive ‘student’ (teacher only teaches when there is a student)
- At some initial cost to the teacher, to set an example that
- Would benefit the ‘student’
Teaching in tandem-running ants - procedure
Background:
Tandem leaders knew the location of food but tandem followers were naive
Tandem leader kept moving only if tapped on her legs or abdomen (gaster) by the follower
Question: is this teaching?
Results: (Blue = less than twice the antennal length between teacher and student = close distance)
Leader movement: depends on distance from follower
- Student follows closely → teacher accelerates
- Student is further → teacher slows down
Follower movement: depends on distance from leader
- Distance decreases → student slows down
- Distance increases → student accelerates
Is tandem-running ants really teaching
YES
- Teaching only in the presence of a naive student
- Cost to teachers: tandem leaders move 4x slower when they teach: median of 1.8 vs. 8.4 mm/sec
- Benefit to students: tandem followers found food faster than when searching alone: average of 201 vs. 310 sec
Culture
A suite of local traditions that uniquely identifies a certain population
Tradition
A distinctive behavioural pattern shared by two or more individuals in a social unit, which persists over time and that new practitioners acquire in part through social learning
Orangutan video clip - tradition and tool use
- Orangutans travel in groups and eat insects, fruit, termites, etc.
Tool for honey harvesting:
- Extracting food from a hole in a living tree is hard, so they make tools
- Process: select a twig, trim it to length, wiggle it to shape, then insert into tree to get what they want from inside
Tradition: Younger members watch and learn so a tradition grows that will be passed on to new generations
Abundance of food = learn in groups = community = copying within the community = culture
ex. Goualougo chimps different tool for breaking into a tunnel vs. brushing out the termites
- unique to the group
Spread of traditions in chimps; pan-pipe poke vs. lift techniques
Observation period:
- For 7 days, only the expert was allowed to operate the pan-pipe (trained in one of the techniques)
- Other group members closely observed the expert
- Then all group members had access to the pan pipe
Results:
- Control chimps: failed to gain food (no expert)
- Poke/lift groups: 15/16 gained food within one minute
- Almost no adoption of the lift technique in the poke group
- Mixed adoption of techniques in the lift group
- Poking might just come easier
- Also true two months after
Conclusion:
If one knew how to get the food using the specific method, all the rest could imitate
Culture in non-human animals?
- Very limited culture in other great apes (chimpanzees and orangutans)
- No known culture in other species
- Other species may have one tradition (e.g. distinct songs in song birds)
Tool use in Chimps vs humans
Chimps:
- Use only simple tools
Ancient humans:
- Used complex tools (e.g traps made of complementary parts)
- Used weapons for hunting
- Humans have developed complex cumulative culture, which relies on language and technology
Brain and learning graphs
positive linear association between brain and body weights
positive association between innovation and executive brain ratio
Current data suggests that: primate relative brain size is predicted by diet (fruit > leaves) but not sociality
Social learning and brain size - 3 measures
- Innovation: novel solutions to environmental or social problems. Examples: use of a club to attack a snake; use of tin cans to make noisy dominance display
- Social learning
- Executive brain (neocortex + striatum) the brain’s structures involved in social learning and innovation
Relative volume of brain region = ratio of the brain region to either another part of the brain or the whole body
Executive brain ratio = executive brain / brain stem
Cultural transmission
transfer of information from individual to individual through social learning or teaching, both within and between generations
Stone play
- Individuals would play with stones, particularly right after eating. They stack up stones and then knock them down
- Started with one individual Glance-6476, and started being transmitted from older to younger individuals (nobody older than her)
Age-specific differences in the use of culturally acquired behaviour:
- Younger individuals: many short vigorous bouts of stone play
- Older individuals: fewer + longer bouts of stone play
Stone play benefits
Motor training hypothesis: stone play may facilitate the development of perceptual and cognitive skills (explains young behaviour)
Adults: behaviour may help slow down deterioration of cognitive processes often seen in ageing primates
- Stone play only seen in populations with significant “leisure time” due to food being provided by humans
Cultural transmission
a system of information transfer that affects an individual’s phenotype by means of either teaching or some form of social learning
What’s So Important about Cultural Transmission?
- Behaviour of a single individual could dramatically shift the behaviours in an entire group
- Individual learning disappears when that individual dies, while cultural transmission allows information to be passed through generations
- Rapid transmission of information throughout a population
- Cultural transmission operates faster than natural selection to change behavioural traits (dozens - thousands of generations vs a few generations)
Copying
an observer repeats what it has seen a model do, and is typically then rewarded for whatever behaviour it has copied
- Rewards can be intrinsic (related to animal emotions or feelings) or extrinsic (food or basic needs)
Guppy mate choice experiment
Results: guppies will choose to court the male another female likes when given the option between that male and a colour matched other male 17/20 times
Copying NOT schooling bacause happens 10/20 times even when they’re far away
Mice respond to stable flies - copying
Background: No immediate response to stable flies. Once bitten, defense is to bury under debris.
Copying: An observer who sees the teacher bit, then hiding will do the same when first exposed to a fly. (without ever having been bitten)
Findings: when their NMDA receptors are blocked, affect neural plasticity, observer will not learn to bury itself as soon as they’re exposed to a fly
What differentiates copying from imitation?
What is copied need not be novel or involve learning some new topographical action—an individual can copy the action of another, even if it already knows how to do what the model is doing
Crop Raiding, Elephants, and Social Learning Anecdote
Background:
Around Amboseli National Park in Kenya, ~1/3 adult male elephants that have dispersed from their natal groups raid crop fields, during which they are in danger of being killed/injured by farmers
Elephants live in complex social networks; individual and social learning
Results: a male was most likely to raid crops if the individual it associated with most often was a crop raider, and the effect was most pronounced when associates were older
Significance: policy making in the future should seek to provide reliable food sources for older males that serve as models for others in their group
Tradition in meerkats experiment
- Meerkats initially preferred the landmark that they saw the demonstrator at
- A completely arbitrary tradition (both landmarks were equally profitable, but one was preferred by other group members) emerged
- After a few days, the traditional preference slowly disappeared: over time they began to explore the other landmark. Once they learned themselves that this other landmark was just as good as the one they had been frequenting, they spent time at both landmarks, eroding the tradition
Conclusion: Social learning produced a tradition, but individual learning led to its demise
Tradition in great tits experiment
Experiment: Two different foraging-related traditions were introduced into a series of great tit populations to study whether traditions established themselves via social learning, and then persisted
Either learned to open a puzzle box while using a blue (slides right) or red coloured door (slides left) from a demonstrator
Results:
- Birds copied the new behaviour introduced into their population, and the behaviour spread quickly.
- New traditions persisted across generations, and did so despite much population turnover.
Teaching in meerkats - hunting prey example
- Older helpers modify their behaviours only in the presence of young pups that are incapable of catching their own prey
- Changed what type of prey they delivered in a manner that would help and maybe even teach the pups (gradually bring more live scorpion as pups age)
- Spent much time monitoring pups after presenting them with food
- Retrieved prey when pups lost their food
- Modified a scorpion (removing the stinger, killing the scorpion, and so on)
- Nudged pups that were reluctant to eat scorpions, increasing the probability that the pups would eat the scorpion that they had initially rejected - These behaviours come at a cost to the helpers: spending time that they could have used to forage for themselves but instead spent with pups
- Benefit to pups: such modifications helped pups learn how to forage on dangerous prey
Common themes in examples of animal teaching
And 2 general categories
- Most instances focus on parent/offspring relationship
- While technically, young could learn from other adults or adults could teach eachother, they rarely do
- Relates to how genetic kinship makes up for the costs of teaching - Two general categories: Opportunity teaching and coaching
a) Opportunity teaching: teachers actively place students where they can learn a new skill (most common)
E.g. helper meerkats manipulate prey for young pups
b) Coaching: teacher directly alters the behaviour of students by encouragement or punishment
E.g. helper meerkats nudge young pups to encourage them to try new foods
Parents teaching embryos - fairy wren
Hypothesis: to minimize the amount of food given to parasites over young, fairy wren mothers emit a vocal password that their young can learn while in the egg, and can then emit when they are chicks, to access food that cuckoo chicks in the nest cannot
Positive correlation between correct vocal password → maternal feeding rate
How the vocal password system works:
Key = amount of time that embryos are exposed to the maternal password
Fairy wren eggs are exposed to the password for 3 more days than cuckoos
= better at mimicking it
Why don’t fairy wren females always teach their offspring the vocal password?
- Cost of females teaching offspring a vocal password: nest predation was higher when females produced more incubation calls/hour
Describe the three types of cultural transmission: vertical, oblique, and horizontal
○ Vertical: Info transmitted across generations
ex. Parent to offspring.
○ Oblique: Young animals learning from adults who are not their parents.
- May be more common in systems with no parental care
○ Horizontal: Information transfer between peers (same age) in adults and young individuals.
Finch song - cultural transmission
Question: There is no cost of hybridization between medium ground finch and cactus finch, but they rarely interbreed. Does cultural transmission play a role in inhibiting interbreeding?
Results:
- Song in finches is culturally transmitted across generations from father to son
Culturally transmitted differences in ground/cactus finch song impacts gene flow across species:
- More females mate with males who sing the song of their own species
- Females avoid males with songs similar to their fathers’ = less likely to mate with genetic relatives because song is culturally transmitted from father to son = song may play a role in preventing inbreeding
- When a male sang the song of another species, interbreeding occurred
Guppy mate choice: cultural vs. genetic transmission
Cultural transmission: observer females that view a model female choose one male over another are more likely to choose that mate themselves
Genetic transmission: heritable preference to mate with more orange males (Para river gupppies)
Results:
Matching males (4%) to 24%: female copied observer mate choice = cultural transmission overrode genetic predisposition
40% orange difference: female preferred the more orange male = genetic transmission overrode mate-choice copying
Conclusion: whether or not female guppies copy a model’s mate choice is determined by a threshold difference in the amount of orange body colour in the male. If the orange body colour is above this threshold, genetic preferences mask any cultural effects.
Are innovation and tool use more common in large-brained species?
- Frequency of innovation, tool use, and social learning were positively correlated with relative executive brain size in primates
- Similar results in comparative studies birds: larger brain size/body ratio is correlated with, innovation, and tool use
Foraging behaviour + examples
searching for and consuming food
Granivores → seeds, nuts, berries
Herbivores → plants
Carnivores → living animals
Scavengers → dead animals
Search image theory → Tinbergen
- Like template theory, as an animal encounters a prey type more and more they form a representation of that target
- Representation becomes more detailed with experience
- Helps them to be more successful at finding this type of prey
Optimal foraging theory (OFT)
a class of models that often employ a mathematical technique known as optimization theory to predict various aspects of animal foraging behaviour within a given set of constraints
OFT model assumptions
- energy taken from prey can be measured in calories
- foragers can’t simultaneously handle one prey item and search for another
- prey are recognized instantly and accurately
- prey are encountered sequentially
- natural selection favours foragers that maximize their rate of energy intake
Deciding what to eat
Should a forager that consumes prey 1 add prey 2 to its diet?
- Under what conditions does the forager take both types of prey?
What the optimal diet model predicts:
1. Once a critical encounter rate with prey type 1 is reached, it alone should be taken
2. The decision about whether to take prey 2 does not depend on prey 2’s encounter rate (how common it is); rather, it is related to its encounter rate with prey type 1
- Makes sense bc if they don’t encounter type 1 enough they will be forced to rely on other options
Optimal Diet Model in the Great Tit
Experiment: mealworms of different sizes presented on a conveyor belt to great tits
Results: the encounter rate of the most profitable prey, not the least profitable, determined whether tits took the least profitable items
Deciding where to eat
How long should a forager stay in a patch of food that it is depleting before moving on to another patch?
What the marginal value theorem (Charnov) predicts:
1. A forager should stay in a patch until the marginal rate of food intake in its patch is equal to that of the average rate of food intake across all patches available
(once feeding on a patch begins, food intake rate keeps decreasing as food is depleted)
2. The greater the time between patches, the longer a forager should stay in a patch. Increased travel time = increased costs associated with travel
3. A forager should remain longer in patches if patch quality in the environment is poor versus rich. In order to make up for the travel costs associated with a move from a patch, a forager has to stay longer in a poor patch than in a good patch to obtain a fixed amount of energy
How does variance in food supply affect a foragers decision about what food types to eat
Risk sensitivity
Risk-Sensitive Foraging:
Patch 1 is always 8 items. Patch 2 is double or nothing. Should our forager consider the variability difference when deciding between patches (even though the mean is 8 in both)?
Three basic utility (hunger state’s relation to value) functions that a forager can have:
- Linear utility function: every additional food item is valued equally
- Risk insensitive: should be indifferent to foraging-related variance - Convex utility function: every additional food item has less value, which we would expect in a fairly satiated forager
- Risk averse: should prefer to forage in patches with low variance - Concave utility function: every additional food item is worth more and more, which we would expect in a hungry forager
- Risk prone: should prefer to forage in high variance patches (worth the risk)
Utility function in yellow-eyed juncos
Experiment: Presented birds with two trays of birdseed, once the bird picked one the other was immediately removed. One tray with a fixed amount, the other with a variable amount.
Results: Hungry birds were risk-prone = concave utility function. And v.v.
Ant origins of agriculture
50 million years ago, some ant species began cultivating their own food by entering into a symbiotic (mutually beneficial) relationship with fungi: The ants promote the growth of the fungi (good for the fungi), while also eating the vegetative shoots produced by their fungal partners (good for the ants)
- during this time they evolved the use of streptomyces antibiotics
Evidence for ants evolved use of streptomyces antibiotics
- All species of fungus-growing ants had Streptomyces bacteria associated with them
- Ants transmit the Streptomyces across generations, as parents pass the bacteria on to offspring
- Only females possess Streptomyces, as only females start new nests that will rely on the Streptomyces to produce antibiotics, and only females are involved in “cultivating” fungus gardens.
- The bacteria found on fungus-growing ants produce antibiotics that were effective only against Escovopsis, a serious parasitic threat to the ants’ fungus garden. Species that were not a danger to fungus-growing ants were unaffected by Streptomyces antibiotics.
Other ways ants clean their fungal gardens (besides antibiotics)
remove fungus infected with Escovopsis by picking up the parasitic spores/hyphae and placing them in their infrabuccal pockets, where the spores/hyphae are killed by chemicals. They then take the dead spores and hyphae and deposit them in a separate pile away from the fungus garden
Foraging and group life
In group-living species, increasing the number of foragers in a group can increase the amount of food each forager receives
Foraging in Bluegill sunfish
Bluegill sunfish feed on small aquatic insects that live in dense vegetation, so they need to be flushed from substrate, and increasing the size of foraging groups may flush more prey out of the vegetation
Positive relationship between foraging group size and individual foraging success up to a group size of 4 fish, due to:
1. More prey were flushed when group size rose
2. Prey clumped together, so when one group member found amphipods, others swam over to this area and then often found food themselves
Foraging and group life - Tai vs. Gombe chimps
Tai chimps:
- Hunting success is positively correlated with group size in a nonadditive fashion: with each new hunter, all group members receive more additional food than they did when the last new hunter was added to the group
- Nonadditive - adding more hunters to a group did not simply increase the amount of food by a fixed amount for each new hunter added
- Cooperation in hunting behavior: social rules exist that regulate access to fresh kills and assure hunters who cooperated greater foraging success than those that fail to join a hunt.
Gombe chimps:
- no correlation between group size and hunting success
- behavioural rules limiting a nonhunter’s access to prey were absent
- nonhunters received as much food as those that hunted cooperatively
Part of the difference in hunting behaviour in Tai and Gombe chimps may be because the success rate for Gombe solo hunters was quite high compared with the individual success rate for chimps in the Tai population, relaxing selection pressure for cooperative hunting in the Gombe population.
Public information + benefit
information based on the actions of others
Allows group members to reduce environmental uncertainty
Public information models predict that: social foragers in poor patches should leave earlier than solitary individuals, because social foragers can use the failed foraging attempts of their group mates as additional information about when they themselves should leave a patch of food
Public information B1/B2 bird experiment
Experiment: B2 birds were allowed to investigate cups with some or no seeds, then B1 birds were paired with them to conduct the task
Results: B1 birds left patches earlier when paired with B2 than when conducting the task alone, also left the fastest when the B2 bird had complete information vs. only partial information
Hippocampal Size and Caching Ability in Birds
Colorado vs alaska
Background: Strong positive correlation between greater food-storing/caching behaviour and hippocampal volume (more caching = remember location of more seeds)
Hypothesis: Natural selection should favour better caching and retrieval abilities in harsh foraging environments where food is scarce, as caching and retrieval is at a premium + should have greater hippocampus than those from food-rich environments
Experiment: Tested black-capped chickadees from either Colorado (food-rich) or Alaska (food-scarce) on their ability to retrieve seeds they had cached
Results:
Food-scarce Alaska:
- Cached a greater percentage of seeds than the birds from Colorado
- Found a greater proportion of their cached seeds
- Made fewer errors during searches
- Hippocampus weighed less than that of Colorado birds, but hippocampal volumes were greater + contained more neurons
Food-rich Colorado:
- Cached less, found less, made more errors, less hippocampal volume
Does phylogenetic history explain variation in caching ability?
Experiment: Researchers mapped variation in caching abilities (noncachers, moderate cachers, and specialized cachers) in corvids onto a phylogenetic tree of this family of birds.
Results: Moderate caching is the most likely ancestral state of caching in corvids
What do these results mean? Suggests that the simplest variety of a trait—in this case caching behavior—is not always the most ancestral variety of that trait.
= independent evolution multiple times
How does developmental variation (birth weight) in honeybees map onto subsequent variation in their ability to learn about food sources?
Experiment:
- Honeybees were weighed on emergence from brood cells
- Immediately tested on their response to a sucrose solution
- At three weeks, tested on a foraging-related learning task
Results:
- Positive correlation between birth weight and foraging-related learning at three weeks of age
- Positive correlation how quickly an individual responded to the sucrose solution after emergence and learning ability
Is there a relationship between foraging innovations (use of a new foraging technique) and relative forebrain size
Positive relationship between relative brain size and the birds’ success in novel environments + this success was due to their relatively high use of innovative new foraging techniques, which increased their rate of food intake
Conclusion: Suggests that there is a fitness correlate with relatively large brains and the innovative abilities associated with them
Foraging traditions in killer whales
Foraging behaviour of endangered killer whales: there is often a pronounced foraging tradition for specialization on a specific prey, even though other prey are present, determined by socially learned preference (ex. Preference for chinook salmon)
Emberizoidea - avian superfamily foraging innovation
Adaptive radiations: bursts of diversification in a clade
Results: Compared to other avian superfamilies, Emberizoidea shows very high rates of both foraging innovation and diversification.
What do these results mean? In addition to things like a propensity for dispersal and a general ability to successfully colonize new niches, one behavioural factor that may be linked to rates of high evolutionary diversification is a propensity to use new foraging techniques.
Does cultural transmission play a role in pigeon foraging behaviour
Red paper
Experiment/results: Pigeons needed to learn to pierce the red half of a paper covering a box of seeds. In each group, an observer pigeon was placed in an arena with the same box:
NM (no model): observers saw no model on the other side of a clear partition
Result: none of the pigeons learned how to get the hidden food
Suggests that: it was a difficult task to master through individual learning
BI (blind imitation): observers saw a model that was eating from a hole in the paper, but they did not they did not see the model pierce the red half of the cover
Result: learned how to to get food from the box, but the time lag until they began feeding from the box was long
LE (local enhancement): observers saw a model pierce the red but get no food
Result: did not learn to solve the food
OL (observational learning): observers saw a model pierce the red and eat
Result: learned how to find the food quickly
Suggests that: important role for cultural transmission in the foraging behavior of pigeons
Does scrounging inhibit an individuals social learning - pigeon research
Experiment: Some of the test tubes contained food, and when a group member learns how to open a tube, the food spills on the floor and is accessible to all
Results: Out of 16 pigeons, only 2 learned how to open tubes (producers) and 14 acted as scroungers.
Two findings suggest that scrounging inhibited an individual from learning how to open tubes via observation:
1. Scroungers followed producers and payed attention to where producers were, not what producers did to get food
2. By removing the two producers, scroungers still did not open tubes or know how to, because they never learned how from producers
When an observer was paired with a demonstrator and had the chance to view the demonstrator forage: over time the observer learned how to open tubes.
=All birds were capable of learning the foraging task.
Damselfly OPTIMIZED innate behaviour
Question: Can damselfly larvae LEARN TO ASSOCIATE an unknown predator with danger? Would they benefit from such ability?
Experiment:
Use the same 3 groups of damselflies from exp. 1
Place all the damselflies in tanks containing the water from pikes fed on mealworms
Results:
- Damselflies exposed in experiment 1 to pike +minnows/damselflies showed antipredatory behaviour to pike + mealworm stimuli → they learned!
- Damselflies exposed in experiment 1 to pike + mealworms did not show antipredatory behaviour to pike + mealworm stimuli → they did not learn!
Behavioural patterns in animals - innate vs learned
Which are evolved
- Many are innate
- Others are learned
- Many are partially innate, partially learned
- Both innate behaviour and learning abilities are evolved traits
Breast feeding - innate vs learned
- A newly born baby has an innate tendency to feed on his mother’s milk
- The newborn quickly learns to identify his mother’s smell and appearance
Niko Tinbergen
Nobel Laureate in Physiology or Medicine for their discoveries concerning organization and elicitation of individual and social behaviour
Innate begging behaviour and learning in gull chicks
Background:
Chicks have an innate response: they know to peck the red spot of their parent’s gull when hungry → indicates that the parent needs to regurgitate
Mutual signalling: parents bill stimulates the chick to beg for food, then the chick’s pecking stimulates the parent to feed it. Signals also tell parents when to stop feeding, not just when to start
Experiment: Used wooden models of parent’s beak and looked at relative pecking response, where hyper realistic model is 100%
Results: Red pencil with white dots stimulates the greatest response. The initial prediction that you need to have a red dot on the beak was untrue. All you need is contrast (white dot on red background, three dots created most response)
Conclusion:
Begging chicks tend to peck at a contrasting dot on an elongated subject = innate behaviour
With experience, the chicks learn to recognize their parents based on vision and sound
2 major mechanisms that can change behaviour over time
- Evolution; is a major biological process
- Learning; is an animal trait that has evolved by natural selection
- Learning abilities are products of evolution
- There is typically heritable variation in learning ability
- Therefore, lower or higher learning abilities, and specific learning abilities can evolve
Evolution
Measured at what level
Change between generations measured at the population level
- Populations evolve through changes in gene frequencies over generations
Individual learning
change within individuals measured on the same individuals before or after some experience
- Individuals cannot evolve
- Not transmitted to the next generation
Selection on learning
Assuming that individuals show heritable variation in learning ability:
- Evolution of higher learning ability by natural selection would require that individuals with higher learning scores would have higher fitness
- To evolve higher learning ability through artificial selection, all we need is to breed only the individuals with the highest learning scores
Quinine experiment - fruit flies and learning
Selecting for learning using pineapple: (odd #)
Training: could try pineapple or orange + quinine
Break: could choose which to lay eggs on
Test: individuals that learned chose pineapple, so they were kept to breed the next generation
Selecting for learning using orange:
Training: switched the conditions to prevent flies from being selected based on preference
Break: could choose which to lay eggs on
Test: individuals that learned chose orange, so they were kept to breed the next generation
Results: after 35 generations there was clear divergence between control (no experience) and selection line. I.e., there was artificial selection of learning ability
- Evolution of learning indicates there is heritable variation in learning ability in flies
- Learning abilities of wild fruit flies are only moderate
- Natural selection does not favour good learning ability in flies
3 key components of the artificial selection experiment
- Training
- Test: learning and memory
- Selective breeding: only of the flies who demonstrated good learning and memory
Is learning heritable? How do you know?
What type of selection was used to test
yes
- Artificial selection selected succeeded, meaning learning is heritable.
- You can’t get artificial selection without heritability.
CREB flies and mice - learning and memory
Results: CREB flies have similar memory to that of normal flies with 10x training. Even with no training, CREB flies do well.
Results: With sufficient training, control mice do as well as CREBa mice. With less training, control mice do poorly, but treated ones do almost twice as well.
Massed vs. spaced training in flies
odour + shock
Results: Mass training resulted in no training, but space worked
Massed vs. spaced training in humans
Results: Spaced training = better retention
Conclusion: This is why we have weekly quizzes and a few cumulative tests
Effects of midterm on score on the final exam
Students read text and then were assigned into one of 4 treatments:
1. No test
2. Multiple choice test
3. Multiple choice test with feedback after each question
4. Multiple choice test with feedback after the whole test
Final short-answer test a week later
Conclusion: Best way to do well learning is
to go through material a few times
- best with 4, then 3
Cognitive enhancement
No drug has been found to enhance cognition!
- adderall and ritalin used
Best cognitive enhancers:
- Good night sleep
- Nutritious meals
- Frequent physical exercise outdoors
- Frequent breaks
- Socializing
Why major increase in prescribing adhd meds
- Overdiagnosis
- Misdiagnosis
- Influence of drug companies on the above
Trend is that those born later in the year within a grade are prescribed more ADHD meds
- maybe just immaturity
Innate behaviour + learning in bumblebees and flowers
innate tendency to fly towards flowers
learning for best flower to approach, behaviour of flowers in their environment
The bumblebee samples different species and learns which one is the best flower in that bumblebee’s specific time and place
When is innate behaviour sufficient?
When there is strong association over many generations between a cue and an environmental feature
When is learning adaptive?
When there is no persistent association over many generations between a cue and an environmental feature, but there is such association over a portion of an individual’s life
Should animals learn everything?
No, because learning has costs:
- time
- cost of error
- cost of brain tissue
- maintenance costs
- opportunity cost (learning vs. reproduction)
Animals should only attend to and learn valuable information
What information is valuable?
Information that increases fitness
How do animals know what information is valuable?
- Evolved innate biases: newborns are naturally attracted to people/faces, talking, etc.
- Evolved emotions: pleasure, fear, etc. (e.g. sweet foods make people happy)
- Repetition of relevant information
Emperor penguins
- Parents and chicks learn individually specific calls
- Sound is more useful than sight
Biases in aversion learning - rats and noisy or tasty water
Conclusion: shows we are selective with what we learn
- Innate bias
- Food poisoning after something novel = assume food caused illness
- Foot pain after a loud noise = assume sound caused pain
Learning
the ability to acquire a neuronal representation of new information
- Looks at acquisition
Memory
the neuronal representation of information
- Looks at retention over time
Adaptive spatial memory: sex differences
meadow voles vs. prairie voles
meadow = polygamous
= greater male home range size
= males will be a better navigators than the females
= make less mistakes than females
prairie/pine = monogamous
Adaptive spatial memory: hippocampus volume
What type of cells
The hippocampus (seahorse shape) has place cells:
Place cells: neurons in the hippocampus that that fire when an animal visits specific regions of its environment = provide an organized map of space (cognitive map)
The brain region that processes spatial memory would be larger in the sex with better spatial memory
- seen in meadow voles
Why should we expect sex differences in spatial memory in humans?
Gen. Evolution
2 hypotheses over evolutionary time:
- Men with larger ranges may have fathered more children
- Women that stayed close to home successfully raised more children
Sexual dimorphism related to distinct sex roles - archaeology
Men have higher remodelling in femurs and tibias = higher mechanical loads = greater range size
Travel by Tsimane, indigenous forager–horticulturalists in Bolivia
Childhood: no travel difference
Adolescence: men travel more
Marriage: sex difference became smaller
Hadza hunter gatherers (Tanzania)
- Men travel farther than women
- Increase from childhood - adulthood
- Declines after adulthood due to childbearing and ageing
- Men: travel is 50% higher than women in adulthood
Twe of Namibia - travel range
Women: typically stay close to home
Men: have a larger distribution, indicating they travel more than women
Men with lovers (more children) travelled more than men without lovers
Twe of Namibia - harm avoidance
Twe women show greater harm avoidance than their male partners
Measures of harm avoidance: spatial anxiety, solo travel
- Women: show higher spatial anxiety
- Men: more likely to solo travel
(45 degree line means that if men and women were identical, we expect all points to be on that line)
Navigation through a virtual maze - males vs. females
- females were slower than males at completing
- women made more errors than men
- women better memory but smaller vocabulary
Navigation in a video game - males vs. females
Males, regardless of city/age, perform much better than women
Sex differences in cognitive abilities – the role of sex hormones
Humans:
- Testes start producing hormones at week 7 of gestation
- Higher testosterone concentrations in male than female fetuses
- In fetuses of non-human mammals, testosterone acts through neural receptors to influence: neuron survival, anatomical connectivity and neurochemical specification
- This produces sex differences in brain structure + function
- Higher androgen prenatal environment in girls = better spatial memory
Testosterone & maze performance in rats
Four treatments:
1. Females from litters with small proportion of males
2. Castrated males
3. Females from litters with large proportion of males (like 2m females)
4. Control (high testosterone)
Results: males and females from high testosterone environments have better spatial memory than those from lower testosterone environments
Do people with extensive navigation experience have a larger hippocampus?
taxi drivers
taxi drivers = larger posterior hippo (spatial memory)
either go into the job due to skill, or develop larger size due to extensive use of hippo
found volume of hippo increased after training
probs due to neurogenesis and survival of new neurons, synaptogenesis
= brain plasticity
Sex differences in spatial memory in humans
hunter-gatherers
- Men have better spatial memory than women
- Men with larger ranges father more children
- Women that stay close to home successfully raise more children
- Important to recognize difference between population variation and individual variation
Effects of computers and internet on human cognition
Most likely, variation in outcomes among people:
- Some may learn and memorise less because info is readily accessible
- Others may learn and remember more because large amounts of relevant information are readily accessible and required for expertise
Reducing specific learning and memory demands on the brain would reduce neuronal tissue devoted to them (bc the brain is plastic)
Classical conditioning
Pairing a biologically potent stimulus with a previously neutral stimulus
Instrumental conditioning
Strength of a behavior is modified by reinforcement or punishment
Non associative learning
individual does not associate a cue with a state
two types…
1. sensitization
2. habituation
Sensitization
increased response to stimuli following the presentation of a prominent stimulus (e.g. loud sound, strong smell)
Habituation
decreased response to a stimulus following the repeated presentation of that stimulus (e.g. loud sound, strong smell)
Sensitization in Aplysia
Experiment: Measure response of aplysia to a jet of water pre and post touch (response = siphon is used to expel waste)
Aplysia responds strongly to the jet of water after it has been sensitized by a touch
touch + movement of water = assumes there’s a predator moving around it = sensitization
Habituation in a worm
Experiment: Measure response to mechanical shock or shadow (both signal predator)
Result:
a. 1st shock: strong response, then nothing bad follows the shock so worm just reduces response
b. Shadow: strong response, indicating that the reduced response from the shock was not due to fatigue
c. 2nd shock: strong response again, indicating that the worm is not tired, followed by habituation
