Exam 2 Flashcards
Behavior is a phenotype
Affected by both genes and environment. Differences in behavior between individuals can be traceable to differences in either genes or environment
Development Of behavior
Two developmental categories of behavior:
– Innate: performed without experience/incentive
– Acquired: gained through experience/learned
Twin studies
Behavioral heritability in humans
– Developmental systems (are dependent upon genetic and environmental input) -> neurophysiological systems (including the brain) –> test taking behavior –> IQ score
Drosophila larva
– More clear-cut example of how differences between individuals can be traced to environmental/genetic differences
– Rover versus sitter fruit fly larva behavioral phenotypes. Larva of one doesn’t move much, other does.
– – Differences caused by a single genetic difference. Crossbred sitter male with rover female to try and prove this. F1 almost all rovers. F2 generation had rover 3:1 sitter ratio. Expected Mendelian ratio.
Mouse water behavior experiment
– A single gene mutation in hippocampus affects spatial learning in mice (alpha-calcium-cal modulin kinase)
– – Put them in water filled tank with platform hidden somewhat underwater. Swims randomly until it finds the platform and then must remember where it is later. There is a mutant that can’t remember where platform is regardless of trial numbers or trial manipulation.
Learning involves environmental modification of behavior
– However… What and how an animal learns is constrained by genes
– Example: taste aversion learning in rats. Good at associating particular taste with nausea – with one trial, will avoid it. Good at associating sounds with electrical shocks. These things are learned but constrained by genes.
– Can’t compare taste with shocks. Can’t pair sound with nausea and get them to stop drinking non-flavored water.
– – And wild, I generalists and need to know quickly if they’re eating something fetid. Need to learn quickly what predators sound like
Vampire bat experiment
Vampire bats don’t have much of a dietary range. Insectivorous bats, however, eat a wide variety of insects, many of which could make them sick.
– Experiments with flavored fluid either mixed with saline or with toxin to make them nauseous – either delayed effect, immediate, or asynchronous.
– – No effect on vampire bats – did not seem to associate the variables. It’s like the worst that’s easily avoided fluids that predictably made them nauseous.
Model for behavioral development
Genes x environmental interactions –> development –> anatomy/including microanatomy (–> innate behavior) and physiology (–> acquired behavior)
Each individual’s behavior equals a mix of genes and environment. Between populations, behaviors can be different solely because of genes.
Do genes for behavior exists
Genes for proteins exist.
– The proteins affects neural development (enzymes, etc), sensory reception (stimuli filtering, etc), cellular communication, production of and response to hormones (hormone can’t do job without receptors in right place with right density)
Etc!
How do you test the role of genes in producing behavioral differences
– Knockout experiments, hybridization experiments, hold environmental condition constant, artificial selection
Knockout experiments
Gene of interest deactivated to see how they behave different from control. Tests single-gene effects only.
Example: female mice with defective FosB gene ignore their offspring, which affected female care for offspring. Showed up FosB gene is necessary to produce normal maternal behavior.
Hybridization experiments
Crossbreed to see diff phenotype type outcomes of different behavior parents
– If there are behavioral variants, read them together. Can see you weather predictions about gene effects on behavior are true
– If polygenic, should be able to hybridize extreme forms of phenotype, expect offspring with intermediate levels of phenotype with a frequency curve
– – Flatter bell curve with higher standard deviation, average is intermediate behavior
Example: blackcap migration (polygenic)
– South German birds migrate to Africa via western route. Eastern European birds migrate via eastern route. Canary island birds don’t migrate.
- Zugunruhe (restlessness of captive birds during migratory times. Length of zugunruhe reflect length of migration in nature) exhibited by different populations
– Crossbreeding Canary Island and south German populations resulted in intermediate migratory route with intermediate length of zugunruhe
– Proved offspring inherit migratory distance and direction behavior
This is an example where two populations from the same species were crossed
Control for differences and environmental conditions
Control for environmental variables that might affect behavior. See if they are different.
Example: garter snake diet preferences. Coastal ones eat slugs, inland ones eat frogs/fish – avoid/not interested in slugs
– Captured pregnant females, raised young in captivity. Offered young either slug chunks or slug fluid on a Q-tip.
– – Crystals next still ate more slugs then and then once despite controlling for environmental differences – support that the preference is genetic
– Coastal snakes tongue flicked more often than inland then snakes in response to slug extract
– This can be attributed to differences in receptor density that makes coastal snakes more sensitive to (proximate or developmental causation)
– – ultimate explanation: not as many slugs inland, not as much selective pressure in favor of individuals who eat slugs
Problems with captivity experiments
Appropriate signs stimuli may not be present, lack of motivation, normal maturation process may not take place
Can do field exps instead
– Control for developmental factors.
– Example: cross fostering in pink cockatoos and Galah
– – Naturally cross foster each other’s offspring. Galahs sometimes lag eggs in same nest holes as cockatoos - chased away and cockatoos raise eggs/chicks. Can take parents with different calls and switch eggs on purpose to try and account for differences in calls
– Call types found in both species: begging, alarm, contact
– Cross fostered galah chicks gave galah begging calls, Gala alarm calls, cockatoo contact calls. Indicates contact calls are learned
Artificial selection
Should be able to produce directional selection to change behavior
– Example: house mouse nest building. Can breed extreme phenotypes among themselves. If genetic variation is responsible, should be able to breed for this extreme phenotype ever many generations to increase the average phenotype
Role of environment in producing behavioral differences
Behavioral development can be affected by things like
Internal environment:
– Hormones
– Environment
External environment:
– Pheromones: chemical signal released by an animal that can affect the behavior of another/affect the course of other animals development and behavior
– Social environment
– Experience/learning
Hormones have two classes of effects on behavior
Activation of effects: trigger behaviors by activating neural pathways that are already in place. Usually occur during adulthood. Effects are transient, meaning that behavior only lasts as long as that hormone is present and in sufficient amounts
Organizational effects: organize neural pathways responsible for behavior
Organizational effects
– Organize neural pathways responsible for behavior. Occurred during early development. Effects are permanent (eg, brain wiring)
Examples of organizational effects: rodent sexual behavior
– Genes on Y chromosome cause development of testes -> testes produce testosterone –> testosterone masculinizes the brain –> the neural pathway in brain that results from this produces male sexual behaviors such as mating/courtship
– – Final expression of male behavior affected by hormone exposure in developmental environment
This can be seen in male parental behavior in Mongolian gerbils. Males positioned between females in utero exposed to less testosterone and fail to mount females in estrous:exhibit more parental care (similar to female behavior)
Egg laying/maintenance behavior in crabs
Normally expressed in females only. However, not so when infected with the parasite Sacculina.
The parasite enters crab at midgut, grows and produces rootlike structures until it is intertwined completely with crabs tissues. When ready to reproduce, extends parts of self out of crab so that it looks like an egg sac. Crab thinks it’s an egg sac too and takes care of it until it hatches to new baby parasites, which looks similar to crab larva.
If the parasite infects a male crab, the root nodules of the parasite neuters the males, which inhibits testosterone and causes the female behaviors that were not normally express and causes it to maintain the egg sac.
Diet
– Some foods act as developmental switches.
– Example: caste determination in honeybees. Worker jelly produces worker bees (4% carbohydrates). Royal jelly produces queens (12% carbohydrates).
Both produced by workers’ salivary glands.
Pheromones
Caste determination in termites.
– Worker/soldier substances inhibit development of own caste. Negative feedback loop.
Example: more workers there are, the more worker substance there is inside colony, which shuts down their development so more soldiers are produced and vice versa
Social
Example: development of task performance and honeybees. Age-related changes in behavior mediated by juvenile hormone (organizational effect)
– Youngest worker bees stay at hive to feed larva/clean/etc. Only forage once they are older to limit reproductive risks since foraging is risky – allows them to contribute to colony before foraging and possibly dying
– – When they make transition depends on balance of bees at other stages within the colony. Affected by social environment. If you add older bees, most of them take on roller forager automatically. If you add younger bees, resident bees which are young, but younger than those added, switch to becoming the foragers
– Socially mediated sex change: female wrasses become male when males removed. (Protogyny)
– – Oldest, heaviest female switches sex when dominant male removed. - - Protandry: start male
Socially mediated territorial behavior in cichlids
– Territorial and satellite phenotypes are reversible in males – depends on status
– Effects whole biology of male. Reversible: can go back told phenotype after
- GnRH neurons -> testes growth -> testosterone -> aggression
– Triggered by ownership of territory
What is learning?
– An adaptive change in an individuals behavior traceable to a specific experience in that individuals life
– Requires flexibility, cannot be considered apart from an animals ecology and evolution
– Adaptive significance of learning is based on the ability to cope with environmental variation
Types of learning
– Temporally restricted learning
– – Imprinting
– Learning that occurs throughout life
– – Associative (and nonassociative learning
Temporally restricted learning
Imprinting
– Bonding with a stimulus through exposure during early life – occurs during a sensitive period very early in life
– – Types of imprinting
– – – Filial: bonding of offspring to parents
– – – Sexual: affinity for certain type of mate (example: cranes prefer mates resembling their parents)
– – – Habitat: affinity for birth site (example: salmon return to natal stream, form affinity for chemical smell of stream)
Types of nonassociative learning
Ceasing to respond to biologically irrelevant. Example: gill withdrawal reflex in Aplysia seahair. Can poke it continuously, eventually it stops withdrawing gills as a stimulus has no serious consequences (NT release from sensory neurons drop.)
Sensitization: increase in responsiveness after exposure to a stimulus.
– Food, potential mate, predator, etc.
– Example: head shock to sea hair reverses habituation. Siphon touch again will cause gill withdrawal.
How do the sea hare neurons work
Facilitating Association neuron: redundancy built into system. Adds excitation that reinforces gill withdrawal reflex.
– Head shock – synapses with excitatory association
–> Motor neuron –> pulls gills in. Adds extra excitation from the other neuron to cause spatial summation to cause the action – restores activity in motor neuron
What are the types of associative learning
Classical conditioning
Operant (instrumental) conditioning
Social learning (copying)
Insight
Classical conditioning
Association between two stimuli. Pavlov.
Unconditioned stimulus (UCS) (meat) –>unconditioned response (UCR) (Salivation)
Neutral stimulus (NS) (bell + UCS meat)–>unconditioned response (salivation)
Over time… conditioned stimulus (CS) –>conditioned response (CR) (salivation)
Operant/instrumental condition
Association between a stimulus and consequence of response towards stimulus. Example: rewarding/punishing for a behavior
Discriminative stimulus (s^d) -> response –> consequence (s^c) either reinforces (+) response or punishes (-) response
Terminology matrix for operant conditioning
Positive reinforcement: reward delivered
Positive punishment: aversive stimulus delivered
Negative reinforcement: aversive stimulus withheld
Negative punishment: reward withheld
When is operant conditioning adaptive
Foraging: choosing the right food. Example: Blue Jays eating monarch butterflies. Monarch butterflies have tocsin and then Blue Jays nauseous. Must learn to avoid.
Agonistic (any type of social interaction that maintains a social relationship) encounters: punishment delivered by social dominants
Mimicry: a consequence of generalization by predators
– Refinement of operant conditioning. Product of a predators ability to learn
Example: male wasps learn to avoid deceptive orchids that attract them via female wasp pheromones – Males will mate with it initially common but stop when it learns that reward is withheld. Negative punishment
Types of mimicry
Mullerian: unpalatable species mimic each other
Batesian: palatable species mimic unpalatable species
Social learning
Copying - lean from each other
- Area copying: behavior is directed toward a place where others are active (or recently active)
- object copying: behavior is directed towards objects or environmental features that math what others are using.
- can be negative reaction too
- in both, behavior is already in repertoire. Contrasts with true imitation.
- Behavior copying (imitation): a behavior novel to the individual is acquired by seeing another individual use it.
- Ex: bird song learning. Milk bottle opening by blue tuts. Food washing by Japanese macaques
- basis for animal “culture”
How important is social learning?
Elephant groups with older matriarchs are better at distinguishing familiar from unfamiliar intruders.
- bunching response: if group is led by old matriarch, goes down the more a group interacts with another group. If older matriarch killed and group is led by more inexperienced female, bunching response does not decline. No one there to give the all clear signal that there is no need to bunch.
- probability of smelling (investigating other elephants) goes down in intact group.
Insight
Using mental pictures if possibilities to solve nov problems
- case study: gave chimpanzees crates and sticks scattered around and hung bananas from ceiling. Have never encountered these objects, the problem before. Problem was figured out pretty quickly without the expected trial/error and learning curve that would be expected.
- evidence of insight in New Caledonian crows: hook making.
Specialized memory in Clarks nutcracker’s
Have best spatial memory
- member of crow and jay family
- most dependent on cached seeds from the fall to get through the winter compared to many relatives, who don’t depend on them as much
- put them in room full of cups with sand - could moved around cups/close cups/change landmarks to test spatial memory
- also tested non-spatial memory (put red dot on cup where they could store food, then moved dot to see if they went back to red dot instead of cup) - we’re no better than relatives at this type of memory task
Specialized memory in black-capped chickadees
Within a species, populations with great dependence on food caches have better spatial memories.
- Demonstrates adaptive evolution (for both chickadees and nutcrackers)
- Alaskan chickadees better at finding cached seeds than colorados chickadees, which are less dependent on them.
Costs of learning and memory
Takes time - might be inefficient at first, less successful. Have to get through this hurdle.
Mistakes can be costly
Energetically expensive
How can you trace the evolutionary origins of complex behavior?
- Fossil records
2. Cladistic analysis
Fossil records
Looks at: tracks (how they moved), skeletons and teeth (what they ate), distribution and position (were they social, etc), nests and burrows to determine how animals may have behaved in past.
Cladistic analysis
Behavior itself doesn’t fossilize, so you can look instead across evolutionary family tree to observe which relatives have a certain behavior, how often it evolved and when.
- examine cladograms, compare more “ancestral” members of group to more derived ones
Meadow vile behavior using Cladistic analysis
Polygyny was ancestral state. gas re-emerged after a switch to monomial then back to polygamy. Can infer why from there.
balloon fly behavior based on Cladistic analysis
Males congregate in lek to compete with each other for females. Fly around with empty balls of silk. We’re there any intermediate steps for this?
- originally food not relate to courtship
- males began presenting insects to avoid cannibalism
- males began wrapping insects in silk (either to restrain insect or make it look bigger to act as an indirect indicator of fitness)
- males began sucking insects dry before presenting them (close relatives still do this)
- now just present empty silk as an essential courtship signal (direct benefit of insect to female lost - female just attracted to silk ball. Became detached from direct benefit, became indicator of male fitness.
How can natural selection account for complex behavior
- same way it produces complex anatomy/physiological processes: cumulative non-random change over time.
how can we test whether a behavior is an “adaptation” (currently being maintained by natural selection)
Determine whether it affects fitness
If a behavior isn’t an adaptation what is it
- Historical baggage inherited by ancestor (ex-courtship in parthenogenic whiptail lizards)
- Arose for a function different from current one (ex: ultrasound detection by diurnal whistling moths. Currently use ultrasound to communication. Ability to hear ultrasound originally for bat detection.)
- By-product of another trait (hyena pseudo penis)
Hyena pseudopenis
Birth canal passes through modified clitoris. Results in high mortality rate during births.
Part of communication system where hyenas inspect each other - clitoris becomes erect, sniff each other.
Did it evolve for communication or is it a byproduct?
- byproduct hypothesis: being dominant and aggressive is so important as a female that this trumps everything else. Pups exposed to higher levels of androgen in utero, which causes more masculinization, grow pseudopenis, and are more aggressive female offspring that will have higher fitness.
Is the pseudopenis a byproduct of androgen masculinization?
- evidence: highest ranking females have much higher reproductive success than lower ranks. Positive correlation between pup survival and mothers status daughters of higher ranking statuses also have high statuses (general correlation)
- Subordinant makes have lower androgen/testosterone levels than dominant ones. Pregnant females have higher levels than females after they’ve had cubs. Supports that androgens are necessary in cub development process
- -females could also have more receptors for the hormone than male hyenas, which have higher levels of testosterone
Why doesn’t natural selection result in perfection?
- Must work with what’s already present
- physiological, anatomical, developmental limits
- competitive selective pressures (food, sex, and fear)
- there are many constraints to natural selection
What are examples of trade offs with natural selection
Guppies: trade off between sexiness an predation risk
- guppies in streams with predators are less colorful than those in predator-free streams
- optimal balance between attractiveness and camouflage
- if you move colorful guppy population to a stream with predators, will become dull within a couple generations
Tugara frogs
- males produce whine calls when calling alone to avoid bat predation
- producing chucking sound (attractive to bats) when calling groups.
- flexibility. Females find chucking more attractive but males must reduce fitness costs associated with bat predation if they chuck while alone
How do you study adaptive function of behavior?
Develop hypothesis
Generate fitness-based hypothesis
–measure one or more fitness currencies (dependent valuables): direct or indirect
Conduct an experimental or observational study
Direct currencies better to look at
Direct vs indirect fitness currencies
Direct
- relate to reproductive process or survivorship up to reproductive age
- gamete production, mating success (how many, how early attained), number of newborns, number of independent offspring, number of viable offspring
Indirect
- foraging success, territory quality, “escape” ability (ex-escape speed)
- ultimately facilitates survival and reproductive success in indirect way
Optimality theory applied to many things like territorial behavior, defense, etc. all toes of behavior where independent variables are quantitative.
Experimentation vs. observational study
Experimental: whine chuck vs. whine playback to measure number of approaches by bats to the two speakers - indirect currency, measuring predation
- vary a factor that you think is important, then measure change in an appropriate fitness currency
Observational: watch frogs singly and note how often they got eaten when just whining or when chucking vs. predation rates in groups
- observe groups using predetermined plans
- sometimes observational approach is all that’s available to you, but can be hard to determine causation or if the behavior is historical baggage.
How do you rule out historical baggage from causation in a behavior during observational studies
Comparative method
- helps rule out evolutionary baggage in observational studies
- compare unrelated species with similar ecologies; predict conditions under which behavior should be exhibited
- look for cases if convergent evolution
- supports that natural selection is maintaining those behaviors
Ex: mobbing behavior in birds. Some gulls nest on ground and mob predators. Other full species nest on cliffs and don’t mob predators.
- cliffs offer protection from predators, so propensity to mob never evolved.
- however, an unrelated species that nests in a group in a vulnerable place also mobs. Nest under ecologically similar conditions to the first gull. The behavior is a production of natural selection.
- convergent evolution: the two mobbing gulls
- divergent evolution: mobbing behavior and non-mobbing behavior in birds if same ancestry because they were exposed to different selection pressures
Advantages and disadvantages of using comparative observation
Advantages:
- allows evolutionary hypothesis testing when experimentation not possible
Disadvantages
- uncontrolled (extraneous) variables
- can’t assume causation
Using either experimentation or observational studies, can test qualitative or quantitative prediction
Optimality theory: used to test quantitative predictions (ex: exactly how far should a bird move empty eggshells away from nest?) (qualitative predictions would be why they move eggshells from nest)
Costs an benefits of behaviors calculated
Fitness currency chosen
A mathematical “Optimality model” is constructed (usually with many simplifying “assumptions”)
Model tested in field or lab
Ex: northwestern crows drop whelks at height that corresponds with height scientists determine is optimal (no point flying much higher because not many additional drops saved)
Is the goal to determine whether animals are optimal? What are the real goals
No.
Real goals: determine what factors are important, determine trade offs animals must make.
Sometimes optimal behavior is based on what others are doing
Best solution is relative. Results in: behavioral polymorphisms (alternative strategies) in populations.
- ability of individuals to change tact is depending on what others are doing (conditional strategy with alternative tactics)
Game theory
Used to study ecosystems where best solutions are relative
Ex: where selective has produced two behavioral strategies where the success of each depends on other individuals in the population
- frequency-dependent selection: in some cases, one phenotype wins out in population (Pure ESS). In other cases, a mixture: as frequency of given phenotype increases in population, fitness level decreases.
Hook nose vs jack male salmon genetic mating tactics.
- phenotypes oscillate over time. Average ratio remains the same over the long haul.
Side-blotched lizard: 3 phenotypes. Orange throat are dominant, good at detecting blue throat males and driving them out of territories. Yellowthroat: yellow has advantage when there are a lot of orange and not blue. Good at sneaking onto Orange throat territories and mating with their females. Results in three-way oscillation between the phenotypes. No optimal phenotype within the population – depends on other individuals present. Negative feedback keeps average mix of the phenotypes similar overtime
