2XC3 Midterm 1

What classifies as an animal?

Living organisms that feed on organic matter, typically having sense organs and a nervous system, being able to respond rapidly to stimuli

Are there more vertebrates or invertebrates in animalia kingdom

Invertebrates make up 80%

What is behaviour?

Coordinated responses of whole living organisms to internal and/or external stimuli, includes cognition

Cumulative culture

Manufacturing of complex technologies that are passed down and improved upon by generation

Example of cumulative culture in non-humans

Japanese macaques washing sweet potatoes in water; the first macaque to innovate and demonstrate this behaviour passed it down to later generations, becoming more efficient and thorough

Mental time travel/meta cognition

Humans have the ability to think critically into the future, and remember what/when/where from the past

Meta cognition in non-humans

Birds show capabilities for future planning as well as memory storage

Whooping cranes in North Amerca

Example of why we study animal behaviour, help bring species back from brink of extinction

2 types of animal learning in Whooping Cranes study

1. Imprinting on heterospecific (different species) caregiver’s behaviour

2. Social learning from conspecific (same species) adult bird

How do we depend on animals?

Population control, pollination, animal research that helps facilitate understanding of human behaviour, pathogen control, learning to avoid certain animals

Example of studying population control

Tiger bee flies prey on carpenter bee larvae via parasitoiding (killing host)

Example of how animal research helps facilitate understanding of human behaviour

Fruit fly sociability testing: Compared sociability in lineages after breeding social flies with each other and non-social flies with each other, caused 50% higher sociability in high lineage after 25 gens than low sociability lineage

Example of non-humans facilitating pathogen control

Indian farmers used Diclofenac to treat pain in cattle, whom vultures feed on after they die, resulted in kidney failure in vulture population after consuming cattle carcasses

• Vultures are sanitizers, clean up carcasses that may be infected with pathogens = higher rates of pathogen transmission (Ex. rabies) in human community

Scientific Method

1. Observation

2. Hypothesis

3. Prediction

4. Experiments

Karl Popper & Falsificationism

A theory only counts as scientific if it makes risky predictions that could be disproven, no finite number of confirmations can prove a theory true

Falsification and Pseudoscience

Science should be set up to favour falsification, pseudoscience is unfalsifiable as it is flexible enough to explain any conflicting outcomes “fallacy of personal validation”

Experiments should aim to be

Double-blind with placebo control group

Placebo effect

 Anticipation of clinical improvement leads to actual improvement

Sham group

Fake treatments delivered identically to the real one but missing the active ingredient

Acupuncture experiment results

No difference between acupuncture and sham group, placebo effect does a lot of work as both groups reported > 50% pain reduction

Why did no treatment acupuncture group report small reduction in pain

1. Regression t the mean

2. Spontaneous improvement

3. Co-interventions (Ex. Painkillers)

Why did the sham acupuncture group report pain reduction

1. Placebo effect

2. Biases

Proximate analysis

Question trait mechanism and development

Ultimate analysis

Question trait survival and phylogeny

5 Classes of Animal Behaviour

Feeding, Fleeing, Fighting, Fucking, Sleep and Social interactions

Invertebrates Feeding

Invertebrates also eat, but very little compared to others due to low metabolic rate

Fleeing

Antipredator behaviour

Why do we fear animals more than car crashes?

Evolutionary mismatch: Our fears are shaped by our ancestral environment, snakes much little threat today compared to before, cars haven't existed long enough for us to develop a specific fear towards them

Caveat to car evolutionary mismatch

Eastern countries (Ex. India, Australia) continue to have snakes as a primary cause of death, less of an evolutionary mismatch

Fighting

Aggression ubiquitous, only occurs over scarce resources, territory, or mates

Sex

Some animals signal their mate quality using colourful displays, most species reproduce sexually

2 broad mechanisms that change behaviour over time

Evolution and learning

How does evolution change behaviour

Via natural/artificial selection, changes behaviour between generations

How does learning change behaviour

Changes behaviour within generations, can be passed down

Phenotypic plasticity

Mechanisms that change physiology, anatomy in an organism (Ex. Tanning, pupils dilating, acclimatizing to high altitudes)

Example of rapid evolution

Ormia & crickets

How did crickets demonstrate rapid evolution

Ormia was introduced to Hawaii in 1980, where silent, “flat-wing” male crickets were discovered in 2003, no flat wing males in 1999, discovered rapid, independent evolution of flatwing morphology. Once the flatwing mutation appeared on any given island, population surged within 12-20 cricket generations (3-5 human years)

• Proven that evolution was independently arisen on each island as a different mutation on all islands were found to have caused the flatwing trait

Flatwing morphology

Flat wing males have female-like wings which cannot produce a song, but can still vibrate their wings

How do flatwing males reproduce

1. Silent males approach calling males and attempt to intercept approaching females

2. or

3. Female crickets have just become less selective when choosing mates

Ormia

Species of flies with good, fine-tuned hearing, locate singing males and parasitize them, female ormia lay eggs on crickets and larvae consume the cricket once born

Learning

The ability to acquire an internal representation of new information to determine subsequent behaviour

What do grasshoppers gain from learning

Being able to tell apart different plant species that provide different nutrients, and remembering where they are is essential for the fitness and survival of a grasshopper

Grasshopper learning case study

Randomly assigned grasshoppers to condition 1: could learn the location of a balanced diet, or condition 2: could not learn the location of a balanced diet

Grasshopper Experiment 2 conditions

• Learning condition: Optimal diet (b) and bad diet (d) paired with the same taste and colour cue constantly, allowing grasshoppers to associate cues (colour/taste) with diet

• Non-learning condition: Optimal and bad diet cues randomized, preventing learning of association

Grasshopper learning experiment results

• Grasshoppers in learning condition were able to associate colour/taste cues with optimal diet, allowing them to learn to go to optimal diet more often

• Grasshoppers in random treatment could not learn association between cues, having a lower proportion of visits to optimal diet

Grasshopper learning experiment results: CAVEAT

• Grasshoppers who didn’t learn association still spent equal amount of time feeding on optimal diet as learned grasshoppers

  • Prop of visits ≠ prop of time spent feeding

  • Learned grasshoppers feeding allowed 20% growth rate

Social learning

Learning from other individuals (heterospecific or conspecific), usually conspecific

Social learning experiment in rats

Tested to see if rats eat novel food that they don’t have experience with, since unfamiliar food could be highly nutritious, or spoiled/poisoned

Social learning experiment in rats design

• Demonstrator rats ate food flavoured with cocoa or cinnamon 

• Reunited demonstrators with observers, and then removed demonstrators once again to observe the observers behaviour with novel food

Social learning experiment in rats results

Observers who interacted with demonstrators who ate cocoa preferred cocoa flavoured food, and vice versa w/ cinnamon

Individual vs Social learning

Information learned by an individual is lost when it dies, information learned from others via social learning can remain in the pop for generations

Advantage of social learning

Social learning also allows for the quicker spread of new behaviour (Ex. rats don’t need many trials to learn which food is safe to eat)

What does artificial selection require

Only requires heritable variation

Longitudinal study on fitness outcomes results

Females that do reach adulthood have highly variable reproductive success (mean = 6-8 offspring), but much more unequal variation in males (mean = 5-10 offspring)

• Many males sire 0 offspring even after reaching sexual maturity, and some sire around 30-40 due to fighting behaviour

Effect of predators on brown anoles

Found higher up in trees and with longer hindlimbs to evade predators

Effect of hurricane on brown anoles

Favoured lizards with shorter hindlimbs

Net acting effect on brown anoles

Multiple selection pressures acting on lizards pointing in opposite directions, longer hindlimb due to predator pressures, and shorter hindlimb due to hurricane pressures

Downstream guppies

High predation site, faster life history strategies

Upstream guppies

Low predation site, slower life history strategies

Guppies reciprocal transplant experiment

Guppies originally from high predation environment moved to low predation environment and adapted to a slower life history and vice versa, proving that natural selection and adaptive evolution can occur rapidly in the wild

Effect of predation on guppy school size

With lower predation pressure sites cause small school size (max ~4), higher predation pressure sites causes larger school size (max ~15-40)

Experiment to test guppy school size (shoaling distance)

• Collected guppies from high and low predation sites

• Allowed them to reproduce to get to the F2 generation to reduce effects of learning and parental effects on predation-avoiding

  • Needed F2 because F0 and F1 will be stressed which can be expressed in physiology = parental effects

• Measured average distance between 4 guppies in the presence and absence of predator-induced pheromones

  • Results: Low predation site demonstrated greater distance between each other (shoaling distance), and high predation sites demonstrated lower shoaling distance

  • Shoaling distance is a plastic trait, it decreases when predator is near but is otherwise stable

Experiment to test if predation site survivorship is hereditary

• Place low and high predation fishes in a high predation environment

  • Results: Guppies from high predation pop’s had better survivorship in a lab experiment

  • Have evolved better anti-predator adaptations

  • Suggests hereditary basis

Fast life history strategy

• Lay many eggs

• Very little to no parental care

• Rapid maturation

• Short lifespan

• High mortality rate

• Ex. Fruit fly

Slow life history strategies

• Offspring have longer gestation period

• Juveniles take many years to reach sexual maturity

• High degree of parental care

• Relatively low mortality risk

• Ex. Elephants

Life history trade-offs

• When mortality risk changes, animals of the same species invest different amounts of energy in various life stages

  • Ex. High mortality risk = higher reproductive rate and lower growth and maturation rate

Narrow-sense heritability (h²)

The proportion of total phenotypic variance in a population that is caused by additive genetic variance, always bounded between 0 and 1

Truncation selection

Measures narrow-sense heritability -> prop of variation of a trait

S (selection differential)

Amount of change that we might expect in approach scores if all variation was due to genetic variation that natural selection can act upon, will ALWAYS be greater than or equal to the R

R (response to selection)

How much truncation selection has changed approach scores across the 2 generations

Heritability calculation

R/S

How is relatedness determined

Common ancestry

How do we explain phenotype

Ultimate + Proximate questions (Ex. How is the red colouration generated + why do they have red colouration)

House finches experiment

 Artificially reddened males were more attractive to females than less bright males, males who are better at foraging = redder = chosen by females because male is more likely to better provide for offspring with his foraging skills

How is red colouration generated in house finches?

Males seek out foods high in carotenoid pigments which redden plumage

Why do males seek carotenoids over other nutrient rich foods avaliable?

Reddened plumages make male birds appear more attractive to females

Endocrine system

Network of glands that secrete hormones directly into bloodstream (vertebrates) or surrounding fluids (invertebrates) to control cells by binding to receptor cites

How does the endocrine system work

• 1. Endocrine gland synthesizes hormone 

• 2. Hormone stored or released into bloodstream

• 3. Binds to receptor on target cell -> elicits response

Peptide hormones

Water-soluble, no carrier needed, fast onset time (Ex. Insulin)

Steroid hormones

Fat-soluble, need a protein carrier, slow onset time (Ex. cortisol)

HPA axis hormone cascade example

• 2 caribou fighting -> winner & loser

  • Losers have greater HPA axis activation

    • Hypothalamus released CRH hormones -> acts on anterior pituitary -> acts on adrenal cortex -> produces cortisol

      • Negative feedback loop w/ cortisol 

  • Losers have increased stressed levels & reduced aggression in the presence of winner

  • Ultimate explanation: Used to reduce potential injury risk in near-future and conserve energy for later battles

Does hormone release guarantee a behaviour?

No, hormones change the probability of behaviour (Ex. Release of testosterone increases the probability of aggression, but does not make aggression certain)

Testosterone and fighting birds observation

Correlation with length of day and testosterone levels due to Hypothalamic gonadol axis

Testosterone and fighting birds experiment

Prevented lengthened days which kept testosterone and aggression levels stable and low 

• Ultimate explanation: Increasing day length is a reliable cue for mating season

  • Males need to be ready to physically compete to defend territory, food, mates, etc..

How is flight or fight behaviour orchestrated?

• System 1: Fast energy mobilization

• System 2: Sustained energy and injury protection

Mongolian gerbil case study

Studied how development of middle fetus was impacted by surrounding fetuses

Mongolian gerbil case study observations

• 2M males develop higher testosterone than 2F males

• Fitness consequences: 2M males sired more offspring and mate quicker with females

• 2M males also showed less parental care than 2F males

Mongolian gerbil experiment results

Castrated randomized gerbils + sham castration which showed more parental care in castrated gerbils, as well as 2M females having fewer litters, fewer mates, and are more aggressive

Prarie voles vs Meadow voles

• Prairie: Socially monogamous, males show parental care 

• Meadow: Socially polygynous, males show little parental care

Voles experiment

Administered vasopressin to prairie and meadow voles to test if Prairie voles have more vasopressin receptors which is important for regulating social attachment and pair bonding

Vole experiment result

Increased parental care to prairie voles but had no effect on meadow voles -> receptor difference

• Not enough vasopressin receptors in meadow voles to respond to it

• Genetic techniques to increase vasopressin receptors makes meadow voles more prairie-like

How do animals guage stimulus strength?

• 1. The same neuron fires several times

• 2. More neurons fire at the same time

Development of brain

• 1. Nerve cells scattered

• 2. Cells serving same function clustered

• 3. Centralized longitudinal nerve cord

• 4. Brain

fMRI with rat brain

• Place male rat in cage with female: Less brain activity

• Place male rat in cage with female + male intruder: More brain activity

  • Respond to potential threat over mate

Mushroom bodies

Where Invertebrates’ spatial navigation system is linked

Honeybees orientation flight

 ~1 week of age, they hover around the nest and explore to learn a spatial map of the area to prepare for foraging duties

Mushroom bodies & foraging observation

Forager bees had mushroom bodies that were ~15% larger than other non-forager bees

• Issue: This could just be due to forager bees being older and having larger brains as a result of development

Honeybees Mushroom bodies experiment

•  Plant a colony of only one-day-old bees 

  • Did not have older bees to rely on for other hive jobs

  • Caused precocious foraging: Bees started foraging way earlier at around 4-7 days old compared to bees that normally start foraging at ~3 weeks

    • Foraging triggers mushroom body growth

    • Precocious forager’ mushroom bodies resembled the size of normal-aged foragers

Midshipman fish sonic muscles

Present in both guarders and sneakers, but guarders have larger sonic muscles than sneakers as well as faster firing rate which allows them to grunt and call to females

Sonic muscles & pacemaker neurons

Pacemaker neurons kickstart pathway to singing