Lecture 6 - Tinbergen's 4 questions Flashcards
What is ethology?
-scientific study of natural animal behaviour
-initially focussed on instinct but later incorporated learning
-mostly lead by European biologists in contrast to the North American psychologists leading behaviourism
Who is Niko Tinbergen?
Naturalist and bird watcher who emphasised a combination of observation and experiments in the field and in the lab.
Originally worked in the Netherlands and was a prisoner of the Nazis.
His lab produced many of the most influential animal behaviour scientists in the 20th century.
What was Tinbergen’s question surrounding Mechanism/causation?
What is going on in this animal right now?
- looks at cognitive, neurobiological, physiological mechanisms that causes behaviour
- proximate causation
What was Tinbergen’s question surrounding ontogeny/development?
What in the past led to this behaviour in this animal?
- looking at the processes in the development in behaviour
- proximate causation
What was Tinbergen’s question surrounding adaptive value/function?
What value does this behaviour provide?
- looks at why the behaviour exists at all for survival and reproduction
- ultimate causation
What was Tinbergen’s question surrounding phylogeny and evolution?
What led to this species possessing this behaviour?
- looks at which species have certain traits and why - tracking evolutionary history of traits
- ultimate causation
what is feature detection?
the correct stimuli can be defined by multiple aspects, including what it looks like and how it moves
What are supernormal stimuli?
Stimuli are recognised by matching a template, but this template doesn’t need to exactly match the real stimulus.
Templates might include abstract combinations of shapes and other colours or involve “rules of thumb” such as incubate the largest round object.
These templates can be hacked by unnatural stimuli which better fit the internal rules.
We call these “Supernormal stimuli” and they can reveal how animal recognition works.
What is fixed action pattern?
“Innate”, Species Typical, Fixed responses that are typically unlearned and performed in response to a trigger
Manipulation of releasers can result in hijacking of behaviour and a resulting arms race.
How are complex animal behaviours organised?
Many vertebrate behaviours are more flexible than fixed action patterns.
But the idea of “innate” and species-typical behaviour raises questions about how complex behaviours are organised in the brain.
Explain ethological action maps
mammals - motor action represented by maps in motor cortex of the brain
maps don’t correlate neatly with anatomy
new work suggests might be organised by natural behaviours
exciting different parts of the cortex result in monkeys carrying out complex actions
what are hormones?
chemical messengers secreted by endocrine glands (or sometimes by neurons) and travel through the bloodstream
How do hormones change behaviour?
By affecting the brain, specific muscles, or other organs.
They are slower than neurons but last longer, suitable for making changes over longer time periods.
Explain the effects of oxytocin in sheep
normally olfactory bulb only reactive to food smells
parturition shift to response to lamb odours
mediated by oxytocin released by hypothalamus
hormones chance sensitivity of brain areas, leading to changes in learning and behaviour
Explain the example of trial and error learning in portia (spiders)
When prey responds to a signal – Portia sticks with that signal.
if prey stops responding- portia sends signals again until finding ones that attract the prey
Explain the Clayton and Dickinson 1998 experiment
Food-storing scrub jays
store favourite food (worm) and okay food (nut)
after 4 hours look for worms first
after 120 hours look for nuts first
What does ontogeny ask?
how did this behaviour in this animal become what it is today?
often focus is on the early life experience but much bigger scope that that
how does an organism go from being a fertilised embryo all the way to being a behaving adults
What are the different aspects of development?
growing up
- maturation
environmental influences
- Developmental induction
- Parental environment
- Resilience + equifinality
learning
What is maturation?
Changes in behaviour due to physical changes in neural and muscular systems
What did Hailman (1969) find in laughing gull chicks?
Increased pecking accuracy over first 2 days after hatching - found maturation occurred and not learning as even chicks that were reared in a dark environment had similar accuracy. Maturation > Learning
What is development?
an interactive process in which genetic information interacts with changing internal and external environments
- No trait is “genetic” as opposed to “environmental”
- No trait is “environmentally determined” in the sense of developing without genetic input
what happens when larvae are exposed to cold temperature?
lower learning ability
lower discrimination ability
poorer decision making
worse reproduction success
What is the biotic influence in locust?
best grouping behaviour depends upon local population density
- 2 morphs (solitary, gregarious)
- which morph develops depends on number of collisions in early life
dependence on a particular factor for a trait to emerge is referred to as developmental induction
What is phenotypic plasticity?
The ability of the organism to alter its phenotype in response to environmental input.
All learning is plasticity, not all plasticity is learning
What is plasticity the outcome of?
natural selection and is dependent on genes
- This means that something being learned is not the opposite of, or an alternative to, that thing being evolved
Whats an example of a rearing environment?
prairie volves
pups reared by both parents experienced more licking and grooming and were less exposed than those reared by the mother alone
family structure influenced the environment developing pups experience
What is an example of development and language learning?
In Japanese “Ra” and “La” are the same sound: ら.
“Ba” and “Wa” however are two distinct sounds: ば and わ
If you test compare Japanese native-speaking adults with English native-speaking adults. The latter are more sensitive to “ra” vs “la” but there is no different for “ba” vs “wa”
What is channeling?
restricting early experiences make some outcomes more likely.
What is self-regulation?
deviation form a developmental pathway results in correcting actions to compensate
What is equifinality?
different developmental pathways can still lead to similar outcomes
What are the general principles for the song development in birds (example of development)?
predisposition
- neural template
importance of experience
- Juvenile hears song
- Adult hears itself sing
plasticity
- Most birds - only sounds close to own song
- Parrots, starlings - great variety of sounds
sensitive period
- song must be heard during first few months
equifinality
- as with language, many patterns of experiencing song produce normal song
What is the difference between function and evolution’s ultimate questions?
Function asks “What is this behaviour for?” based on studies of today’s animals.
Evolution asks “How did this behaviour evolve?” by reconstructing evolutionary history.
Example of functions of behaviour: gulls paddling
Why gulls paddle :
Paddling results in worms coming to the surface
paddling attracts males
paddling scares potential predators
- different potnetial hypotheses
What did Stephen Gould and Richard lewontin criticise?
naive speculation about functions
some features might not be specific adaptations but are actually byproducts of selection for a different trait
What are the 3 main approaches to studying function in animal behaviour?
- Observation – what are the natural consequences of the trait?
- Experiment – does changing a trait change consequences?
- Comparison – do similar problems result in similar solutions?
Explain the first method to study function in animal behaviour (observation)
when there is a natural variation in a trait, measuring the consequences can suggest a possible function
sparrows and finches add cigarette butts to their nest-fewer parasites
Explain the second method to study function in animal behaviour (experiments)
no natural variation= creating variations using experiments
allow us to better test the effect of a particular feature and we can keep all other factors the same
e.g. why do gulls remove egg shells?
- broken shells might hurt chicks
- broken shells might prevent other chicks hatching
- broke shells might make incubating difficult
- broken shells might increase disease risk
- broken shells might break camouflage
- to test, Tinbergen & colleagues put out painted eggs with and without broken eggshells nearby.
- found eggshells attract predators
Explain the third method to study function in animal behaviour (comparison)
hard to test if behaviour associated with function if only compare similar species
what we need is some diversity in both relatedness and behaviour
Explain the example of ground nesting in comparison
aggressive to predators
chicks don’t avoid edges
good chick recognition
Explain the example of cliff nesting in comparison
less wary of predators
chicks avoid edges
less chick recognition
explain function and evolution
similar problems lead to convergent evolution of stimuli solutions
different problems lead to the divergent evolutions of different solutions
shows behaviour
How can we reconstruct evolution?
In Tinbergen’s time the main method was to identify homology – features that are the same because they come from a common ancestor.
What counts as a species?
Carl Linnaeus (1707-78) developed a hierarchical categorization system based on how similar organisms are to one another.
What is the difference between monophyletic and paraphyletic grouping?
monophyletic – contain all descendents of a common ancestor.
paraphyletic - Groups that contain only some descendents of a common ancestor
- many common kinds of animal are actually paraphyletic
Explain the biological species concept (Mayr 1942)
a group of individuals capable of reproducing and producing fertile offspring together
speciation is therefore result of reproductive isolation
When is reproductive isolation more likely?
In populations that are further away from one another
What are ring speces?
A special case thought to result from a continuous population expanding around a barrier.
Although the two end populations cannot interbreed they are connected to a chain of populations that can
What is meant by cladistics?
an approach which recognises that features can be both gained and lost over the course of evolution. Builds evolutionary trees based on most likely pattern of gains and losses given current traits.
Today DNA is used to reconstruct evolutionary (or phylogenetic) tree, but we can use any observable sets of features
Explain molecular clocks as a way of using DNA to date divergences
if neutral changes in DNA occur at a constant rate then we can also use degree of difference in DNA to date when lineages diverged
variation in the rate of change
affected by generation time, metabolic rate, natural selection
requires some calibration for each application
how can we reconstruct evolution?
today DNA is used to reconstruct evolutionary tree, but we can use the logic of cladistics to test sequences of behavioural evolution
Explain the example of the evolution of dancing bees
honeybees communicate the location of good flowers to each other via waggle dance
waggle dance contains info about the distance and direction of the flowers
How can we plot the evolution of dancing bees?
- use up-to-date phylogenetic tree
- assign traits
- determine simplest pattern of acquisition and losses
reveals common origins and independent evolution
what is the simplest solution for birds?
finding the simplest pattern of gains and losses isn’t always easy
among birds there are 3 groups capable of vocal learning
these groups aren’t closely related
brain structures are very similar
What did Hall et al find about what evolves first with old world babblers nests?
Hall et al. (2015) compared many species and found that that domed nests co-evolved with ground nesting.
Domed nests in trees evolved first on the ground and then moved into trees.
Suggests originally driven by predation
What drives evolution of a trait?
The order of acquisition can tell us the factors that lead to a trait spreading in a population.
Males in many species show exaggerated sexual characteristics that look like they require a lot of resources? How are these not removed by natural selection?
Darwin (1871) suggested that these survive because females prefer these traits – and so they lead to higher reproduction.
Sensory bias or male quality?
male swordtail fish have a distinctive sword on their lower tail
the function of the sword is to advertise to females who prefer males with swords
can test by comparing preference in the related platyfish species which do not have a sword
