Lectures pre M1 Flashcards
Animal
An organism feeding on organic matter, typically have specialized sense organs and respond rapidly to stimuli
What characterises animals (4 things)
- One of the 3 kingdoms of multicellular organisms (other two are plants and fungi)
- Feeds on organic matter
- Typically has specialised sense organs and a nervous system
- Able to respond rapidly to stimuli
The PQ4R method for effective learning
Preview the material and identify sections read as units
Questions for each section heading
Read while trying to answer the questions
Reflect
Recite the info and answer your questions
Review
3 multicellular kingdoms
animals, plants, fungi
Why study animal behaviour
- we are animals
- relevant to understand human behaviour
- to avoid some animals
Whooping crane video
- Have human foster parents
- Use crane puppets to feed so no humanization
- Humans dress up birds to help them fly
- Idaho farmer rears to avoid humanization
- Kent teaches them where/how to migrate in his microkite
- Population from 16 in 1954 to 600 wild birds in Canada
2 aspects of learning: Chicks imprint on caregiver, young learn migration routine from adults
Why do we enjoy having other animals around
- Humans have strong innate satisfaction from “friendly” species
- We extend our sociability to other “friendly” species
- They are important to our ecosystems
Why share earth with birds?
- Important to ecosystems and we enjoy having other animals around
What happens if no vultures
- Recent 95 % decrease in vulture pops due to poisoning
- Increase in human diseases and deaths bc vultures are sanitizers
How animals affect apples
- Pollination (bumblebees, honey bees, other)
- Pests (maggots, worms) -> ants protect from pests in return for sugar
- Biological control (some insects feed on flies, ex. Parasitoid wasps deposit their eggs into those of fruit flies)
- Seed dispersal (poop out seeds from fruits)
Fly learning and human mental health
- Memory-enhancing drugs and treatment of human learning disabilities
Fruit fly video - Tim Tully
- Similar genes to humans
- Tim Tully tests the memory skills of fruit flies
- Put room lined with electrical current
- Two tubes, one with a certain smell that alerts shocks
- If they train 10 times in succession, no long-term memory
- With rest interval of 15 mins, they form a long-term memory
- Flies with extra Creb gene can learn after only one training session = photographic memory
- Set switch on to convert more short term memories to long (Good for age-related memory loss)
Plane crash into Hudson river (2009)
- Everyone survived
- Bird tissues removed from plane engine = they were responsible
- Canadian goose and they identified where it came from; using hydrogen isotopes to see what they ate = came from Labrador
Use techniques like bird radar, robotic bird, and researching migration to avoid another crash
Applications of goose crash
- development of management techniques that could reduce the risk of future collisions
- for migratory vs. residential
Integrating this info with:
bird migration patterns
bird-detection radar
bird dispersal programs at airports can minimize such collisions
Bird-airplane collision prevention
- Airport control teams that do research to reduce collisions
- Israel research (birds don’t like to fly over open water)
reduced collisions by ~85% saved US $40 million per year - Bird forecasts showing migration intensity - planes can reroute
What is critical thinking
exercising thorough judgement or observation (analysing)
- does it make sense
- reasonable conclusions
- what issues remain unresolved
Takes time and effort
Ana”lysis” + elements
Breaking up a whole into parts; examining in details
- Purpose/Question
- Assumption/theory
- Data and facts
- Conclusions
- Implications/consequences
Intellectual standards
Clarity: can I understand it?
Accuracy: is it right or wrong?
Precision: can it be more specific/detailed/exact?
Relevance: is it sufficiently related to the issue?
Depth: complexities and interrelationships?
Breadth: multiple points of view?
Logic: does it follow from the evidence / make sense?
Significance: is it important?
Fairness: conflict of interest / biases?
Scientific method
- Define the question
- Gather information and resources
- Form hypotheses and testable predictions
- Plan experiments to serve as critical tests of the prediction using properly designed experiments by independent teams
- Do experiments and collect data
- Analyse data
- Interpret data and draw conclusions that serve as a starting point for new hypotheses
- Communicate results via peer-reviewed journals
Blind experiment
The psubjects do not know their to treatments.
- Relevant for all science
- Bias is an issue
Double blind experiment
Both the data collector and subjects do not know subjects’ assignment to treatments
Caveat: often, people can guess..
- Relevant for human subjects bc were biased to ourselves
No-blind vs. blind bias experiment - with rats
In an experiment involving rats with similar abilities, non-blind observers will record higher performance for rats labelled bright than for rats labelled dull
Why blind or double blind?
2 reasons
- In all experiments, experimenter is always biased
- In human experiments, experimenters and subjects are biased
- In humans, there is a very strong placebo effect
∴ The only proper protocol for experiments with humans is double blind
Placebo effect - acupuncture
The expectation and anticipation of clinical improvement
Indicated by: large difference between sham treatment (placebo) and no treatment (same treatment)
acupuncture and sham (placebo) treatment both had the same score
Causes of observed improvements in the control treatments
5 reasons
- Spontaneous improvement
- Statistical regression to the mean = a statistical phenomenon that can make natural variation in repeated data look like real change
- Placebo effect (psychological factors)
- Biases (e.g. patient being polite)
- Co-interventions (e.g. pain killers)
Scientific approaches - ultimate vs proximate
Ultimate = Why?
- function
- adaptive significance
EVOLUTIONARY FORCES
Proximate = How?
- mechanism
- machinery (genetics, physiology, neurobiology)
- operate within the lifetime of an organism
NATURAL SELECTION
Sparrows experiment (edge of extingtion) - stress
Glucocorticoid hormones such as corticosterone have been linked to stress responses, so birds on the edge of the expansion (furthest from Mombasa), and hence in the most novel environments, would show the strongest surge in corticosterone when exposed to a stressor (especially during breeding season)
Invasive house sparrows experiment - proximate and ultimate answers
Proximate perspective (how): increased corticosterone leads to better memory of stressors
Ultimate perspective (why): the payoffs for better memory in environments with novel and unpredictable stressors should be greatest in leading edge populations during invasions
Ultimate analysis of plumage in the house finch (Geoff Hill)
Ultimate
- Why do males, but not females, actively search for carotenoid-based foods
~helps males obtain mates
- Why do females prefer males with bright plumage
~disease resistance, feed offspring more, better foragers
Proximate analysis of plumage in the house finch (Geoff Hill)
Proximate
- What causes between-population differences in female coloration
~availability of carotenoid foods
- What causes males and females to differ in plumage colouration
~different foraging strategies
Are hormones proximate or ultimate
a proximate cause
Endocrine system
a communication network that influences many aspects of animal behaviour (hormones released by either ductless glands or neurons)
- Primarily composed of a group of ductless glands that secrete hormones directly into blood
Major hormone-producing glands in vertebrates + what happens while they malfunction
- adrenal gland
- pituitary gland
- thyroid gland
- pancreas
- gonads
- hypothalamus
hyposecretion or hypersecretion affects functions like growth, metabolism, reactions to stress, aggression, and reproduction
Endocrine cells
where + what do they do
Cells within endocrine glands that synthesize and then secrete hormones
Neurohormones
Hormones that can be released directly into the blood by neurons (typically in the brain)
Hormones
act as chemical messengers, affecting target cells that reside some distance from the gland-secreting hormone
- same hormone can have different effects on different target cells
- almost always transported through the bloodstream and all cells (except one) in the body have a direct blood supply
Target cells + process of binding
cells with the receptor site for a particular hormone
- hormone has no effect on a cell unless the cell has the correct receptor
- hormone reaches the cell and binds to the receptor site
- a series of interactions occurs that affects gene expression and protein synthesis
- these changes and directly or indirectly affect an animal’s behaviour
Hormone-receptor complex
one sentence analogy
the receptor site (lock) on the surface of the cell is not activated until the correct hormone (key) reaches it
Birds - what causes release of a hormone into the bloodstream
and what hormones are increased
- Breeding season = spring/summer = cued by changes in day length
Day lengths increase → increase in levels of gonadotropin (sperm production) and testosterone (makes males more aggressive towards one another to get females, guard mates, build nests, and defend their brood)
Protein hormones
hormones made up of strings of amino acid
- can be stored in endocrine cells for delayed release
- hydrophilic (aq soluble) so they don’t need a carrier chemical
- larger = greater half-life
- most common hormone in vertebrates
If small: peptide hormones (ex. prolactin)
Steroid hormones
ex. testosterone
- can’t be stored = immediate release
- hydrophobic so they need a chemical chaperone to move them through the bloodstream
- bigger lag time between stimulus and production (compared to protein)
Ecotourism
is designed to draw tourists to beautiful ecologically endangered areas of the world, using the funds generated from this tourism to protect the wildlife in these areas, and to promote the local, often indigenous, human culture that lives around the ecotourism site
Magellanic penguins in Argentina - ecotourism & stress
- Adults exposed to tourists have habituated to their presence and show reduced defensive responses (and corticosterone) in the presence of humans vs with those not exposed
- Very young penguins exposed to tourists showed much higher levels of stress hormones (plasma corticosterone) than those from control groups
Why?
- in ecotourism areas habituated adults leave nest and spend less time brooding as they walk near humans
- causes stress + temperature change stress for chicks
Animals have three interactive systems
input output type
- Input system: made up of all the sensory systems (smell, sight, etc)
- A central processor: made up of integrators that process and integrate the sensory info received
- Output system: effectors such as muscles that move when stimulated
Hormones priming + testosterone example
prime animals so that they are more or less likely to behave in a specific way in a specific environment
ex. testosterone and winning a fight feedback loop
when baseline levels of testosterone are high, males are primed for aggressive behaviour when encountering another male (if they win a fight due to high baseline testosterone, this increases testosterone more)
Mouse fetus in development
if a developing male mouse fetus is surrounded by females, it’s exposed to lower levels of circulating testosterone, so it will be less aggressive and less sexually active than males that were surrounded by male fetuses
Fight or flight response
- Stressor (ex. predator)
- hypothalamus responds along two pathways
a. first pathway
- burst in epinephrine (adrenaline) and norepinephrine leads to an increase in blood sugar and oxygen delivered to vital organs
- nonessential systems (digestive, reproductive) are shut down
b. second pathway
The following hormones are released by the hypothalamus to increase sugars:
- corticotropin-releasing hormone (CRH): leads to ↑ cortisol
- growth hormone-releasing hormone (GHRH)
- thyrotropin-releasing hormone (TRH)
- Aldosterone production to increase water retention and reduce bleeding if the stressor causes injury
In Utero Exposure to Hormones - male gerbils
- testosterone levels in 2M males were significantly higher than in 2F males
Caused them to
-mount females faster and ejaculate sooner
- have more offspring
- spent less time with offspring after birth (less parental care)
In Utero Exposure to Hormones - female gerbils
Preoptic area of the hypothalamus (gerbils): controls copulatory behavior + is sexually dimorphic, meaning that males and females show different activity patterns in the preoptic area
- 2M females have preoptic metabolic activity that resembles that of males more than that of 2F females
- 2M females have 20 percent greater metabolic activity in the preoptic area of the hypothalamus than do 2F females
Vasopressin - what it does
important roles in social behaviours like reproduction + parental care in mammals
Prairie vs. meadow vole vasopressin
Prairie voles are monogamous:
- both males/females have a single mate each breeding season
- males display parental care and guard their mates
Reason: more vasopressin receptors in the ventral pallidum area
Meadow voles are polygynous:
- males mate with multiple females during a breeding season
- males do not display much/any parental care or prosocial behaviour towards mates
Reason: fewer vasopressin receptors in the ventral pallidum area
Experimental administration of vasopressin to male prairie voles increases monogamous behaviours, while administration to meadow voles does not b/c meadow voles lack the receptors to bind the extra vasopressin
NEED RECEPTORS TO GET MORE VASOPRESSIN
Honeybee foraging - hormones
when bees usually go from housekeeping to foraging for food outside of the nest, it is associated with an increase in juvenile hormone III (JH III)
- increase in JH III is correlated with the shift to the forager stage
- bees that had been allatectomized (and thus had no JH III) began foraging significantly later than bees in control groups, poor navigators, no other major behavioural changes
Octopamine
foraging honeybees
- Modulates learning + memory in honeybees
- Forager bees have higher concentrations of octopamine in their brains
- Octopamine reaches its highest concentration when a bee switches from nest bound activities to foraging activities (including foraging-related flight behaviour)
Plainfin midshipman fish - hormones
2 hormones
2 types
Type I
- males build nests
- 4x larger
- higher gonad-to-body size ratio
- produce sounds in many behavioural contexts: grunts when in aggressive contexts with other males, hums when courting females
- if selected as a mate, remains on the nest after a female lays her eggs there
Type II
- “sneakers”: they don’t build nests, but stay around the nests of type I males, then dart in and shed sperm in an attempt to fertilise the nesting female
- small
- lower gonad-to-body size ratio
- do not hum to attract females, rarely grunt
type I males: higher Kt (testosterone androgen) - associated with sound production - and lower cortisol
type II males: higher cortisol (glucocorticoids)
Plainfin midshipman fish - anatomy
AVT and IT
Midshipman’s vocal organ is a set of paired sonic muscles.
- innervated by “pacemaker” neurons
Type I males:
- larger sonic muscles w/ more muscle fibres
- pacemaker neurons fire at a rate of 15-20% higher than type II
- Arginine vasotocin (AVT) inhibits activity in the neurobiological circuitry associated with sound production
- Isotocin (IT) has no effect on sound production
Type II males:
- smaller sonic muscles
- pacemaker neurons fire at a lower rate
- AVT does not affect vocal motor activity and sound production
- IT inhibits activity in the neurobiological circuitry associated with sound production
Neuroethology
neurological underpinnings of behaviour (nervous system and behaviour)
Neurons
specialized nerve cells that have an axon and fire action potentials
- over evolution, neurons that served specific functions became clustered
Axons
nerve fibres that transmit electrical information from one cell to another
- morphological variation = speed of nervous impulse affects the speed at which animals respond behaviorally. thicker diameter = faster impulse
- each neuron has a single axon
Dendrites
- fibres on the neuron that receive impulses from other cells
Nervous impulse
- stimulus
- reach threshold and fire an action potential
- at the end of an axon impulse jumps against the synaptic gap or releases neurotransmitters
- ends when terminal neurons stimulate the effector (ex. a muscle) or with the secretion of a chemical that causes an endocrine gland to secrete a hormone
Mushroom bodies - honeybees
In invertebrates, spatial navigation is associated with this cluster of neurons at the front of the brain
- lets foragers have spatial navigation through visual or olfactory cues
- mushroom bodies of foragers were larger than of younger nurses
Bee mushroom body nurse/forager experiment
- formed a colony composed only of one-day-old bees to induce early foraging behaviour
- bees in the experimental treatment began foraging at around four to seven days of age
- the configuration of the mushroom bodies in these advanced foragers resembled that of normal-aged foragers
= NEURAL PLASTICITY
Brain Size and Problem Solving
- puzzle box to get to food inside
- mammalian carnivores with brain sizes that are relatively large for their body mass are better at solving foraging-related problems
Sleep and Predation in Mallard Ducks
Unihemispheric sleep
- Mallards can sleep with one eye open and one hemisphere of the brain awake, a behavior that allows them to stay alert to predators while resting
Position matters
- Mallards on the edge of a group rely more on unihemispheric sleep compared to those in the center, showing that birds adjust their sleep behavior based on predation risk. Birds on the edges sleep with the open eye facing away from the group, toward potential predators.
Slow-wave sleep
- EEG recordings show that the sleeping hemisphere enters a state called slow-wave sleep, which allows for quick responses to danger while not fully waking the bird. This signature sleep pattern ensures that the bird remains partially alert even during rest.
- Unihemispheric sleep is also observed in aquatic mammals like dolphins, whales, and seals. It helps them perform critical tasks, such as swimming to the surface to breathe while sleeping.
Animal behaviour
self generated movement of either a body part or the whole body in animals
FOUR Fs
Major components of behaviour that most species have:
- Feeding
- Fleeing
- Fornicating / reproducing
- Producing offspring for females, successfully reproducing for males - Fighting/aggression
- Not necessary but common
- Most commonly for access to (good quality/safe) food or females
ANIMAL LIFE HISTORY - four components
- Survival
- Growth
- Reproduction
- Ageing
Fitness = _ + _
Fitness = survival + reproduction
A young animal must avoid being someone’s food and feed to grow and avoid starvation
The two mechanisms that can change behaviour over time
- Evolution: change over generations in the proportions of individual organisms differing genetically in one or more traits
- Learning
What mechanisms change other biological traits (anatomical, morphological, physiological traits)
- Evolution: change over generations in the proportions of individual organisms differing genetically in one or more traits
- Experience-based adaptation: changes resulting from exercise, pupil adaptation to light, acclimation to temp, altitude, etc.
- Age-related changes: growth, ageing, etc.
Evolution
A change over generations in the proportions of individual organisms differing genetically in one or more trait
Functions of singing
- Attract and court females
- Other communication (threat, ownership, asking for food)
- In many species only males sing
Hawaiian cricket wing singing
Male cricket must sing to attract and mate with females, but singing may attract Ormia flies which kill the male
Female ormia parasites lay eggs on the crickets and larvae consume them
Evolved flat wings that vibrate but cause no sound
Wings more similar to those of females
Rapid, independent evolution (separate islands) of flat wings within 12-20 gens
CONVERGENT EVOLUTION
How do silent crickets still mate
- Females have become less selective
- Silent males approach calling males and attempt to intercept approaching females
Learning
the ability to acquire an internal representation of new information
→ An individual may use that information to determine subsequent behaviour
Grasshopper learning
- balanced diet vs deficient diet
- citral or coumarin odours
- brown or green card
- learning treatment group or random treatment group
- learn through colour, taste, location
- allowed to learn ‘naturally’ to prefer balanced over deficient diet
- learning resulted in 20% higher growth rate
usually = reproductive success
Individual vs. social learning
Individual learning
- Info lost when the individual dies
Social learning
- Learning from other individuals
- Info continues on for generations
- Faster spread of learned behaviour
Ethology
the study of animal behaviour
4 ethology types of questions
Tinbergen
Mechanism:
What stimuli elicit behaviour?
What sort of neurobiological and hormonal changes occur in response to, or in anticipation of, such stimuli?
Development:
How does behaviour change with the ontogeny, or development, of an organism?
How does developmental variation affect behaviour later in life?
Survival value:
How does behaviour affect survival and reproduction?
Evolutionary history:
How does behaviour vary as a result of evolutionary history, or phylogeny?
When did a behaviour first appear in the evolutionary history of the species under study?
M/D proximate
S/E ultimate
Scientific method
Scientific observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses.
Galef scavenging rats
Cocoa vs. cinnamon food
Should I eat new food?
Unfamiliar food may be highly nutritious, but it could be spoiled or poisonous
Learning through eating the food is risky
Learning from others is safe
Observers that interacted with demonstrators who ate cocoa preferred cocoa
Vice versa for cinnamon
Can be passed along through generations (ex. From observers to their children)
Cultural transmission via social learning
Foundations of behaviour
- natural selection
ex. silent crickets and mole rat xenophobia - individual learning
ex. grasshopper balanced diets, female bird mate choice - cultural transmission
ex. cocoa rats
Behaviour Levitis
Behaviour is the coordinated responses of whole living organisms to internal and/or external stimuli
Mole rat xenophobia
- Tightly knit groups as only one breeding pair so they’re all genetic relatives
- Those in moist mesic environments have less resource scarcity than those in arid environments
- More aggression towards strangers in arid populations with resource scarcity
- Less aggression when male-female interactions than same-sex bc they still need a few new members to come breed
Female birds mate choice
- Female bird mates with multiple males in her life and prefers the ones whose offspring were successful or who make good mates
Ethology three approaches
- Conceptual
- integrating formerly unconnected ideas
- ex. kin selection and indirect vs direct fitness = inclusive fitness - Theoretical
- Entails the generation of some sort of mathematical model of the world
Ex. models to maximise energy when choosing prey or foraging
- Not trying to mimic the natural world, more so trying to make predictions that may or may not match real behaviour - Empirical
- Observational or experimental studies
- Correlation ≠ causation
- Experimental better for understanding correlation than observational
Cultural transmission
a transmission system in which animals learn through various forms of social learning
Evolution of antibiotic resistance
Microbial evolution and growth arena plate (MEGA)
120 x 60cm
Visual observation of bacterial evolution on a large antibiotic landscape
Duration 2 weeks
X-axis = antibiotic concentration
Artificial selection
the identification by humans of desirable traits in plants and animals, and the steps taken to enhance and perpetuate those traits in future generations
Artificial selection - dogs
- reinforce behaviours like general activity, obedience training, concentration, affection demand, aggression toward dogs, anxiety, and interest in targets
Artificial selection - aggression in fruit flies
- To study the evolutionary biology and mechanisms of aggression (ex. In anderson lab)
- Have 20 000 genes, many similar to humans
- Used to learn about cancer, parkinsons
- Aggression used to learn about depression, etc.
- Shine light that activates neurons and makes them fight or flirt, same neurons!
Emotional arousal
Evolution by natural and artificial selection
- both must have heritable variation
A.S.: the variation in reproductive success (fitness) of individuals is determined by humans who decide which individuals reproduce
N.S.: the variation in reproductive success (fitness) of individuals is determined naturally
Heritable vs. uninheritable human traits
Uninheritable
- Language
- Cultural customs, religion, dressing style, traditions
- Skills
- Hair style and skin tan
Inheritable
- basically everything else
Fitness
Lifetime reproductive success
- product of reproductive rate and length of reproductive lifespan
Red deer (elk) on Isle of Rum - lifetime reproductive success
Females rarely survive till 3 years to even start reproducing (see graph)
Average 6-7 babies/lifetime
Males also rarely make it to reproductive maturity
Many males still don’t have babies even if they make it to reproductive age
Most females DO have babies if they make it to reproductive age
Lab-born fish experiment
- Take lab born fish, one group from population evolved in high predation pool and other from low predation pools
- Use 2nd generation lab-raised individuals to ensure real predation experience doesn’t affect their behaviour (To eliminate parental effects)
- Measured average distance between 4 individuals in the presence and absence of predator-induced alarm pheromones
- Fish at high predation pools have evolved tendencies to form larger groups
- Fish at high predation pools also have evolved more effective predator inspection (more frequent and from farther distance)
Result: matched the behaviour of their ancestors (-ish)
Genetics definitions
Chromosome: long strand of DNA consisting of different genes
Gene: the functional unit of heredity
Locus: a site on the chromosome occupied by a certain gene
Allele: one of several forms of the same gene
Mutation: alteration of a DNA sequence
Polygenic traits
- many genes involved in a trait’s expression
- QTLs (quantitative trait loci) are genes that control polygenic traits
- if the inheritance of a genetic marker is associated with the inheritance of a particular trait, the marker must be linked to the trait
Huntington disease
Determined by only one gene
- H is close to C marker
Adaptive significance of anxiety
- Preparation for bad situations
- Many emotion levels are adaptive
- Being more anxious means you take less risks = you live longer
Graph variation
Variance (σ2), standard deviation (σ, or SD) and standard error (s or SE)
Sources of variation
Genetic variance = average amount of variance among genotypes
Environmental variance = average amount of variance among individuals within the same genotype
Bumblebee genetics of behavioural development - for gene
- Young bees start as cleaners, then feed larvae, then feed nestmates, then pack pollen, then forage
- Respond to the demand over their life
ie. young can be foragers or old can become nurses - Analysis of ~5500 genes (out of ~14,000)
~2000 genes showed different levels of expression in nurses & foragers - Can modify genes if demand for a specific role is needed
“for” gene is seen more in foragers
- Identified by Marla Sokolowsky
- ForS are sitters and move less, forR are rovers and move further
Phenotypic variance
Genetic variance + environmental variance
Vp = Vg + Ve
Broad-sense heritability
h^2 = (Vg) / (Vg + Ve)
Vg = Genetic variance Ve = Environmental variance
Narrow-sense heritability
h^2 = (Va) / (Vp)
proportion of phenotypic variance caused by additive genetic variance
Va = additive genetic variance
unlike Vg which consists of additive and non-additive
Narrow-sense heritability = slope of the regression
Additive genetic variance
the deviation from the mean phenotype due to inheritance of a particular allele and this allele’s relative (to the mean phenotype of the population) effect on phenotype
Slope of curve
Heritability
If a trait is heritable
Vg > 0
Arctic terns
- Great hovering ability while stationary
- Then go dive for fish
- Bring the fish to the ladies
The Bahamas archipelago
Many small islands are used as “natural labs” for experiments, observation, manipulation, replication in natural populations
Prey dynamics between curly tailed lizard and smaller brown anole lizard
- Introduced curly to island with only anoles (control), number of anoles decreased and more likely to become extinct
- Began to move to higher thinner branches to avoid predation shortly after import of predators (within a year)
- Natural selection acting on morphology
- Males with longer limbs to run faster and escape from predators
- Females who were larger and faster to escape and harder to eat once caught
“The modern synthesis”
- What animals do and why they do it (ultimate question)
- How evolutionary processes shape traits
Docile foxes - artificial selection
- Since late 1950s
- Dmitri Belyaev and Lyudmila Trut selecting tamest and most docile foxes in Siberia
- Only allow tamest - calmest and prosocial towards humans - to breed and parent the next generation
- Has produced tame foxes that can be held and pet by humans, and who seek human contact
Docile foxes - domestication syndrome
Common suite of traits including…
- Floppy ears
- Mottled colouration
- Curly tails
- Juvenile characteristics
What causes domestication syndrome
- Belyaev thought trait byproduct of selection for tame behaviour and humans have always just selected for tameness and all other traits are just genetically linked to changes in tameness
- Wrangham says neural crest cells explain how tameness is linked to domestication syndrome; during embryonic development these cells move along the neural crest then migrate to other areas, selection for tameness might reduce the number of these cells and affect traits associated with domestication syndrome
Pack hunting wild dogs - natural selection
- Hunting behaviour - alone or in groups - is a component of phenotype (observable property) as a result of genotype
- In the theoretical past, individuals that hunted in packs got more meat on average than those who hunted alone
- Dogs who ate more could produce more offspring
- Offspring would also like to hunt in groups
- Trait increase in frequency over time
Natural selection requirements
- Variation in a trait → different varieties of a trait
- Fitness consequences of the trait → varieties must affect reproductive success and/or longevity differently
- Inheritable → trait can be passed down to the next generation
Genetic variation
How to get more
- Mutation (any change in genetic structure)
Addition and deletion - point mutations
Base mutations - substitutions of nucleotides
Silent mutations - base mutations with no amino acid changes - Genetic recombination
In sexually reproducing organisms
Chromosome pairs line up and cross over during cell division
Random - Migration
Nongenetic pathway
New individuals arrive from other places
Mode of inheritance
- If none, fitness differences cannot be passed on and naturally selected
- Genetic transmission or cultural transmission
- Narrow-sense heritability: measure of the proportion of variation in a trait that is due to additive genetic variance
- Behavioural differences can be a result of genetic differences
- Measured in heritability experiments
Truncation selection
Truncation selection experiments allow us to measure narrow-sense heritability
Truncate = cut off
Truncation selection - experiment
- Label mean as x0
- Cut off population level variation by only allowing individuals with scores greater than some value to breed → score is labelled as x1
- Label mean of offspring (generation 2) as x2
Selection differential
maximal amount we could expect natural selection to change approach scores if the score was a genetic variation upon which natural selection could act
S = x1 - x0
Response to selection
how much truncation selection has changed approach scores across generations 1 and 2
R = x2 - x0
Heritability
Heritability = R/S
% of all variance in approach that is due to genetic variance upon which natural selection can act
Low → 0.0-0.1
Moderate → 0.1-0.4
High → 0.4-1
Parent-offspring regression
- When narrow sense heritability is high, behavioural variation in offspring should match that of parents
- Greater role of environmental variance in determining behaviour = lower narrow-sense heritability
Cliff swallows research - Brown and Brown
- When parents/offspring raised in diff environments, still join similar group sizes
= correlation not a function of habitat
IF group size preference was due to parents and offspring living in the same environment, correlation would disappear when they moved to diff environments
BUT the result was that group-size preference was heritable = parent-offspring regression
- Put babies from small colonies in larger and vice-versa
- Found individuals still favoured the group size of their parents (not their foster parents)
- Shows narrow-sense heritability
Symmetry
→ indicator of genetic quality in that they have fared well in responding to changing conditions
More asymmetry in stressful environments
Taita thrushes - stressful environments
- Either in low, moderate or high degeneration (damage/disturbedness) forest sites
- Left and right tarsus bone asymmetry with more stressful environments
- Can help conservationists identify populations at risk and help before it’s too late
Sociobiology
The study of the evolution of social behaviour
“The selfish gene”
- Favoured by natural selection
- Not in the emotional or moral sense
- Just because they increase reproductive success
- Any allele that codes for a trait that increases fitness will increase in frequency
- Genes produced appear to be selfish
Antipredator behaviour in guppies - adaptation
- Waterfalls act as a barrier to predators, upstream weak predation, downstream high predation
- Little gene flow between sites (up/down stream)
- High predation sites guppies mature faster, produce smaller and more offspring, and channel lots of resources to reproduction
Why?
Predators are large enough that guppy size doesn’t matter, they can eat them all
More offspring is hoping at least one will survive - Low predation sites have a single small fish predator (rivulus hartii)
Why?
If offspring are big enough they can survive these predators
Natural selection favours producing fewer larger offspring that can quickly grow large enough to avoid the predation of R. hartii
2 components of antipredator behaviour
shoaling (schooling=group cohesiveness) and predator inspection (tendency for individuals to move towards a predator to gain information)
In Turure (lp) vs. Arima river (hp)
- When guppies transferred from high to low areas and vice-versa, eventually converged the behaviour of the new group
- When returned to original began to shift back
Why? - Either natural selection maintained their behaviour regardless of where they went or
- There was a slow shift in behaviour then a slow shift back
- Shows natural selection can take a long time or a short time and can act on antipredatory behaviour
Kinship and naked mole rat behaviour
- Mole rat colonies have high within-colony relatedness
- First vertebrates to display eusociality = extreme sociality (often seen in insects)
- A reproductive division of labour in which individuals in certain castes reproduce and individuals in other castes do not. (queens and workers)
- Overlapping generations, such that individuals of different generations are alive at the same time.
- Communal care of the young.
- Genetic relatives share copies of the same alleles
- Natural selection favours cooperative and altruistic behaviour among kin than unrelated individuals
- Relation up = cooperative and altruism up
- Mole rats more related than any other non-inbred species
0.81 relatedness
Phylogeny
Darwin had “two great laws” centred on
1. The conditions of existence
- The living (biotic) and nonliving (abiotic) environment that sets the stage on which natural selection operates
2. Common ancestry
Phylogenetic trees
- Study common ancestry and evolutionary history, introduced by Ernst Haeckel
- Helps explain why different species share a behaviour; because a common ancestor had it
Reading the phylogenetic tree
- Branch tips = taxa
- Splits at nodes
- Common ancestors at the splitting or branching points
- Root is the common lineage from which all species on the tree are derived
- Drawn in either tree format or ladder format (doesn’t matter which)
Tool use in New Caledonian Crows
Tools are not only used by humans (although we like to think so)
These crows used barbed leaf tools from Pandanus trees and shrubs to extract prey from under tree bark
Prey grab inserted twig or leaf
Learn by watching older toolmakers
Start with simple stripped twigs, then use hooked twigs, then branched twigs with whittled ends
Safeguard their favourite tools for later use
Usually use the left edges of leaves because they prefer to use their right eye and right side of their bill to make tools
Why?
Maybe their low predation and low competition let them have enough time to test these tools out and their long developmental period gave them time to teach their young
How to make a phylogenetic tree
Measure some traits
a. Either developmental (embryological), molecular, or behavioural
b. Or number of related structures (ex. of bones), morphological or anatomical
Homologies → a trait shared by two or more species because they share a common ancestor
Homoplasies/analogies → a trait shared by two or more species because they evolved it independently, not due to a common ancestor (plastic = molded)
- Oldest state of a trait is the the ancestral or primitive trait
Picking your tree
- Many possible phylogenetic trees - all hypotheses
- Pick the one that is the most parsimonious
- Can use to make inferences about natural selection
- Convergency vs. ancestral linkage
Comparative method - phylogenetic trees
- collect information on a pair of traits in different animals to see if they often go together
- If natural selection has favoured this pair of traits, they will often be together
Positive relationship between cognitive function and sleep / WBCs
- Because sleep may strengthen immune system because energy that is invested in our activities when we are awake can be diverted to boost the immune system during sleep
- Sleeping longer can help recovery speed, help with antibody responses, and help us suffer less severe symptoms
- Also correlates with larger amygdala size = improves memory
Measure white blood cells which are related to immunity, use red blood cells and platelets as a control
Found positive correlation between sleep and WBC count, negative correlation between sleep and parasites
Ray-finned fish - actinopterygii
- parental care
- 400 families of fish, 20 000 species - telosts aka bony fish
- Made phylogenetic tree using morphological and genetic/molecular data
- There were found to be multiple origins of parental care (no parental to parental)
- Aka the stepping stone model of no parental, paternal, biparental, maternal was false
Phylogeny and courtship behaviour - Poeciliidae
- Males either have bright colours and the female will choose to mate with them
- OR males are drab and mate by thrusting their gonopodium after approaching from behind
- Using mitochondrial rRNA they looked at phylogeny
- Gonopodial thrusting was determined to be the ancestral (primitive) state
