biol 278 experiments

Crab-Eating Macaque Study

Question: Why do they sleep in sleeping tree?

• Food source? (trees were barren)

• Predator avoidance? (trees were exposed)

• “Advertising”? (show monkeys across river that this is their territory)

Results: Advertising their territory to monkeys across river!

Spallanzi: Owl and Bats Night-Vision

Question: How do owls and bats see at night?

Manipulations:

1) Place owls and bats in darkness and test flying

• owls could not fly well in darkness, but bats did!

• Results: Owls need light, bats do not

2) Hooded bats and then transparent hoods

• Results: Bats can’t fly in hoods; it’s the hood, not the light manipulation

3) Blind the bats with opaque disks on eyes

• Results: Bat’s flew fine; not vision definitely

4) Plugged ears with wax

• Results: did not fly well and did not feed; need hearing for flight?

5) Control: Brass tubes in bat ear - one plugged one not

• to test if “something in ear” made the bat not want to fly

• Result: bats with plugged tubes did not fly, unplugged did fly; bats need hearing to fly in dark

Hilara Sartor Silk Sac Nuptial Gift

Showed the evolution of the empty silk nuptial gift

• M approaches F while she is eating so he can mate with her… but she doesn’t know if she should eat him or go on a date…

• M gives F prey, if she accepts she will eat and he will mate with her

• Evolutionarily, M with the biggest prey will win the F, so M wraps it with silk

• Then, it becomes bigger cocoon, smaller prey (saves M energy)

• Then, it becomes wrapping random things

• Eventually… M gift wraps nothing at all!

Greylag Geese

Example of a FIXED ACTION PATTERN

Experiment: gave geese different objects instead of eggs to see if they’d roll the objects back into the nests

1) stereotyped (all geese do this)

2) triggered by sign stimulus (all the objects are the same as the egg)

3) plays out to completion (could remove egg mid roll, and goose will still complete it)

4) genetic, still not learned (born knowing)

Sticklebacks and Territoriality!

Stickleback males are territorial towards other males, but let other females come into the nests to spawn.

Question: What is signal to be aggressive? Is it the appearance of males - their red bellies?

1) Grey Fish looking model - M was indifferent

2) Red belly fish looking model - M did not like

3) Red belly, not fish shaped - M did not like

Results: presence of red belly is a sign stimulus!

Digger Wasps

Question: do digger wasps use visual cues to come back to nest?

1) Put pine cones around nest, after wasp exited, they moved the pine cones

Result: Digger wasp came back to pine cone circle first, then went to original nest

2) Need to test for olfactory variable!… Put scented plates in one part, then moved scented plates, but kept pinecone circle the same.

Result: Wasps followed visual cue, went to pinecone circle with unscented plates, did not follow the scented plate.

Pavlov and Classical Conditioning

Before experiment:

Food —> Drool

Bell —> Nothing

Conditioning:

Food + Bell —> Drool

After conditioning:

Bell —> Drool

Cat Box and Operant Conditioning

Cat can escape the box if it presses a pedal

• At beginning, it was random because cat didn’t know what was going on

• Animal learned because after many trials, it took a quicker and quicker time escaping!

Nature vs. Nurture - Gulls

• Chicks approach parent; Open and closes beak; Grabs parent’s bill; pulls down paren’t bill —> process is RELEASER for parents to feed the chick

• Seemed like a FAP that was purely nature, but… day old chick was fumbling with process.

• Experiment: raised chick in incubator w/o chance to beg, and the chick never learned!

• Conclusion: Steps 3&4 (grabbing beak and turning head); Steps 1&2 are innate (approaching parent and opens and closes beak)

Trinidadian Guppies and Natural Selection of Behaviors

Upstream - low predation (not as bright, sexually mature at a young age, produce more & smaller offspring)

Downstream - high predation (swim in larger, tighter schools, stay farther away from predators, inspect suspected predators more often)

Experiment: 200 guppies from high-pred site transferred upstream to low-pred site

Result: After 11 years (30-40 gen), the manipulated pop evolved schooling and pred inspection behaviors that are similar to low=pred pop than to ancestral high-pred pop.

Stabilizing Selection in Cichlid Fish

Experiment: Compared growth rate of fish in different-sized patches of food!

Used divided trays to create food patches, added 1 fish to one patch of food, added 4 competitors so focal fish has to defend the food patch (territory)

Measured amount of defensive behavior with different sized food patches

Result: Defending larger territories required more work; more chases per minute

Then… measured growth rate of fish defending different sized patches, result that the medium sized territories had the best balance of cost and benefit!

Directional Selection in Hawaiian Crickets

Island of Kauai, cricket calling disappeared because parasitic fly invaded from North America - listened for victims (males) cricket calls and then laid its eggs inside back of cricket - maggots eat the cricket!

Result: Now a serious downside to being a calling male cricket - now a natural selection against calling, but females still prefer calling!

Interesting! Males evolved to not have sound-producing wings, so they don’t get attacked and they survive!

Females prefer males who make sounds, so how do males do this?

1) silent males hang near chirp males and intercept females; 2) silent males evolved to more around more; 3) F on Kauai have evolved to be somewhat less choosy - no longer require males to chirp!

** Convergent Evolution!!

Disruptive Selection in Spadefoot Toad Tadpoles

Tadpoles are all diff - detritivores (consume detritus & small inverts), carnivores (consume inverts), intermediates (generalists; pretty rare)

Rare because of disruptive selection? —> do detrit and carni have higher fitness?

Growth of different morphs when given detritus as food → detritivores did better than intermediates which did better than carnivores

Ability to catch shrimp as a function of morphology:

carni > intermed > detrit

Conclusion: indiv with specialized traits on either end of the spectrum have higher fitness than indiv with intermediate traits

Digger Wasps - Mixed Evolutionary Stable Strategies (EES)

2 strategies to maintain burrows - diggers (dig their own burrows), burrowers (use abandoned burrows) —> all genetic strategies!

Frequency-Dependent Selection: advantage to borrowing (no energy spent), this goes away if diggers are rare because burrows are then rare, diggers are rare, they are then selected for!

Populations eventually reach equilibrium!

Maze Running in Rats - Artificial Selection

Breeding animals = manipulating offspring genetics

Experiment: 1) tests rats in same maze for 2 weeks, count errors, 2) select rats that made less errors and breed them & do same for high error, 3) test next gen, do same selection process & again, breed low-error rats with each other!

Result: 2 bell curves appeared, so ability to learn responded to the breeding, we can conclude a genetic component!

Experiment 2: Raise some genetic strains in different environment, which differened in the amount of novelty the animals experienced while growing up, then tested the rats as adults!

Result: both genetics and environment influence the behavior!

Classical Genetics: Hygienic Behavior in Honeybees

Worker bees feed larvae and take care of the hive. Sometimes some get American Foulbrood bacterial infection, and worker bees must remove or identify this - they uncap and remove the infected larvae! Some hives show the behavior and survive disease, other’s don’t and are wiped out.

Experiment: Identified hives that “bred true” - all offspring the same, crossed hygienic x unhygenic

Result: all offspring were unhygienic, so unhygienic behavior is dominant, while hygienic must be homozygous recessive!

Experiment 2: Backcross there hetero unhygenic offspring with hygenic homozygous recssive parent

Result: 4 different types of behavior seen in offspring (some bees did both uncapping and removal, some bees did neither, some only uncapped, some only removed)

What about U (uncapping), R (removal) —> UuRr & uurr => 2 genes involved but 4 behaviors!

UuRr - no uncapping or removal

uuRr - uncapping no removal

Uurr - no uncapping

uurr - both uncapping and removal

Salamanders and Personality

Experiment: obtained 10 sets of 4 salamander larve, each set from same egg mass; raise each larvae alone in aq. w/hiding place

Regular water - low pred risk; Water from tank with fish - think high pred risk!

Measured amount of time spent in open vs in refuge

Result: “low risk” larve spent less time in refuge than “high risk” larvae

Linear correlation between time spent out of refuge when it was “safe” and when it was “risky”; bold => safe, would still be bold when “risky”

Spatial Learning in Mice

Experiment: Making “knock-out” transgenic mice - lacked gene for NMDA (memory + spatial awareness), tested for ability to remember the spatial arrangement of a swimming chamber (for hidden platform test)

Result: knock-out mice were slower than normal controls in learning position of the platform

Experiment 2: Knock-in mice with over expressed NMDA

Result: knock-in mice learned quicker than control! Thus… NMDA is involved in learning and memory

Scouting Behavior in Bees

What makes a food scout become a scout?

Experiment: observed food scouts, and looked at their mRNA being transcribed to see what genes active

Result: 16% of mRNA exhibited differences between scouts and non-scouts. Even though genes are related, behavior is likely influenced by which genes are active!

Paramecium Avoidance Behavior

As a result of contact with object, that triggers “stretch-sensitive” calcium channels to open at that location, cillia change motion to flow backwards and “away” from object!

Locust Flight - Control of Patterned Movement

Experiement: Attached locust to stick, 1) remove platform below feet (triggers pattern), 2) test ‘command center idea” by removing brain —> wings still move!, 3) test “requirement for sensory feedback” by removing wings —> muscles still move!

Result: nervous structures or central nervous system must contain the central pattern generator!

Tritonia Swimming and Cell Circuitry

Brain consists of fused ganglia, and when the slug senses danger it escapes with a sudden thrashing movement.

• Experiment: Brain is immobilized in small platform, but body is unrestricted and allows researchers to record nerve cells while animal demonstrates swimming behavior

• DFN (dorsal flexion neurons, make U shape) and VFN (ventral flexion neurons, make arch shape) —> MOTORNEURONS that cause muscles of body wall to contract

• What makes DFN and VFN fire alternatively? —> central pattern generator!!

Worm Detection in Toads

• Example of a “stimulus filter” —> finding worms in an environment full of other things

• hunting technique is called “sit-and-wait” method

• Experiment: toads were presented with different shapes and sizes, researchers measured rate of turning toward the image as the image was moved

• Turns when wide, turns when tall and wide, but also a certain height makes it unusable

• Result: “Stimulus edge length” needed to be achieved! The receptor is a circle, so thus the edge length needed to be hit (the exhibitory center)

Bat Detention by Noctid Moths

Why does the moth dive, but other times it gets out of the way? —> controlled elusive maneuvers!

• sensory neurons in ear signal to the flight muscles and brain

• 2 paths the info can follow: reflex path (ear to flight muscles, bypassing the brain if bat is close!), graded response (path directly to brain!)

• One side (A1 from one sides is active), above (wings up: A1 active, wings down: A1 inactive)

Tricky Moths

Tiger Moth: makes ultrasonic clicks when bats are hunting & “jams” bats echolocation

Luna Moth: flutters tail which makes a sound that wrecks the bat’s aim so they try to attack the tail & miss the moth

Gill Withdrawl Reflex in Aplysia

Habituation: accustomed to a stimulus and its reaction to stimulus becomes reduced or eliminated

Sensitization: animals response to a stimulus becomes extreme after some sort of negative effect

Experiment: touch siphon 1 time, the animal will show gill reflex, but if you touch it repeatedly after several touches, animal begins to ignore you!

Habituation in Aplysia

• Muscles could be fatigued? (if simulate with electrode then muscles contract fine)

• Nerve cells function during sim? (sensory cell fires action potentials when siphon is touched)

• Are interneuron and motorneuron not firing because they are fatigued? (no - if simulated artificially, they still fire action potentials)

• Result: sensory cell does fire action potentials in response to the signal but the signal does not reach the motorneuron or interneuron, thus the synapses must not be working! (loss of Ca++ going in, which causes no neurotransmitter release, no signal recieved by motorneuron, and no signal sent to muscles so no gill withdrawals)

Sensitization in Aplysia

Experiment: touch the siphon and also pinch the slug, you create sensitivity!

• after bad thing happens —> facilitating interneurons dump serotonin onto axon terminals of the sensory cell, which causes the Ca++ channels to stay open for longer, causing a longer/stronger contraction

Satiating Leeches

Experiment: bathe hungry leeches in serotonin, analyze behavior & psychological responses,

• Result: satiated leaches act hungry!

Experiment: simulate serotonergic neurons in the leach brain - natural source of serotonin

• Result: satiated leeches acted hungry

Experiment: block action of serotonin with 5,7-DHT, a neurotoxin

• Result: hungry leeches acted satiated

Experiment: matched leeches in pairs according to size, and allowed one of each pair to feed to satiation

• Result: satiated leeches had less serotonin

Experiment: remove some blood from belly of leech and wait a few weeks, the amount of serotonin increases

• Result: a clear link b/w physical need for food and serotonin levels, which leads to “hungry” behavior

Anoles and Hormones

Green anoles have gonads that shrink outside of the breeding season —> growth of testes causes increase in testosterone

Experiment: castration of anole (dewlap display decreases), addition of testosterone implant (dewlap display increases)

Dewlap display ==> testosterone levels

Red-Sided Garter Snakes

Snakes testes shrink but grow back after hibernation. Hibernation needed, and after hibernation they immediately court and mate even though testes are small and testosterone is 0

Experiment: captured animals at end of summer when testosterone was still high, then ½ left intact (controls), ½ were castrated so there was no source of testosterone

• Results: next 3 years, the % of intact males who courted females stayed high, but % of castrated males who courted decreased with each year

• Looks like testosterone affects behavior months after, too!

Activational and Organizational Hormonal Effects in Rats

Males (mount), females (lordosis)

Organizational effect —> testosterone during days 1-5 because it reorganizes brain to make permanent changes

Activational effect —> testosterone in adulthood because it triggers a behavior!

** Testosterone does not affect a female in adulthood (bc no test. in youth), and also a male who has been castrated (bc no test. in youth, has a “female” brain)

Monogamy and Polygyny - Genes or Environment? Voles!

Prairie Vole (female spend more time in direct contact with offspring, nursing and huddling - males are monogamous and nest with female!)

Meadow Vole (female spends less time, males do not nest with female, and have many females per season - polygynous)

Cross-Fostering Experiment: baby meadows were put into prairie nests, prairie’s accepted them as their own and gave them typical parental care.

Control: baby meadows put into nests of other meadow voles (different parents but same species)

Results: cross-fostered female meadow voles spent more time than controls huddling & nursing young!; 4/8 cross-fostered male meadow voles nested with their mates and spent time with young and were monogamous (prairie vole behavior)

Conclusion: parental behavior is highly influenced by environment!! but 4/8 fostered males were still polygynous so still some genes!

Genes, Hormones, and the Brain with Voles

Vasopressin - prairies copulating with same female —> surge of vasopressin… so does being with a same female cause a feeling of reward for the male? does this lead to monogamous behavior?

3 transgenic lines of prairie voles:

1) Avpr1A-vp: extra copy of avpr1A expressed in reward center

2) Avpr1A-cp: extra copy was expressed in differeny brain area (unrelated to reward center)

3) Laz-vp/cp - bacterial lacZ gene was expressed in the VP and CP as control for gene manipulation

Behavioral test: prairie male caged with a non-estrous female, then given a chance to spent time with same, familiar female or a stranger

Results: males with extra vasopressin receptors in the reward center spent sig. more time with the familiar female, but this was not seen with other lines!

Next: created transgenic meadow voles (polygynous) and males with extra vasopressin receptors in reward center spent dramatically moe time huddling females in a monogamous unusual way!

Conclusion: prairie voles are monogamous because they have vasopressin binding naturally to reward center when they hang out with same female; meadow voles do not have this! that is why they are polygynous!