Animal Behavior Exam 2

Front 1

Biological Clocks

Back 1

-Biological clocks are mechanisms of timekeeping
in organisms
-A biochemical basis for clocks is likely
-Evidence points to the brain as the clock’s center
-Advantages:
-Permits animal to “anticipate”
environmental change - e.g., fiddler crab and incoming tide
-Timing of behavior with an event that cannot be sensed directly - e.g., bees visiting flowers distant from hive
-Continuous measurement of time - e.g., change in bee dance as sun “moves” across the sky
-Characteristics of clocks:
-Cycles continue in absence of environmental cues such as light-dark or temperature cycles
-Cycles are stable and quite precise (but not perfect!)
-Biological clocks govern repeating cycles
of behavior – the length of time involved varies with species and the particular behavior.
-biological clock aid bees in dance language throughout day

Front 2

Biological clock in honey bees

Back 2

-go to flowers at particular time in day because flowers also have biological clocks
-visit

Front 3

Circadian Rhythm

Back 3

-24 hour cycle (approximately)
This pattern persists under constant laboratory
conditions, but there will be some “drift”.

Front 4

Circannual Rhythm

Back 4

-1 year cycle (approximately)
This pattern persists under constant laboratory
conditions, but there will be some “drift”.

Front 5

Biological Clocks: Daily

Back 5

-Nocturnal vs. diurnal activity patterns
-Honeybee feeding at flowers

Front 6

Biological Clocks: Lunar / Tidal

Back 6

-Fiddler crabs active when tide is out, return to burrows when it comes in.

Front 7

Biological Clocks: Monthly

Back 7

-Reproductive cycles
-Palolo worm (marine) reproduction
-Ant lion construction of pit-fall trap for capturing pray which is larger during full moon.

Front 8

Biological Clocks: Annual

Back 8

-Bird migration

Front 9

Naked Mole Rat

Back 9

-lacks circadian rhythm

Front 10

What governs clocks?

Back 10

-Early controversies:
-Internal vs. External regulation
-Endogenous vs. Exogenous
-“Zeitgeber” (time-setter): external cues “entrainment” – setting the clock.

Front 11

Golden-mantled
ground squirrel
hibernation

Back 11

-Evidence for endogenous rhythms?
-Arousal from hibernation
with increasing temperature
-metabolism down, heart rate down, do not urinate, deficate, or eat
-Hibernation persists despite: constant temperature, fixed photoperiod, constant food access - hibernation not affected by environment, all internal

Front 12

Palolo worms breeding

Back 12

-break apart - epitoke and palolo - epitoke releases gametes - happens on 7th night after first full moon following autumnal equinox

Front 13

Squirrels isolated from external stimuli at
birth – maintained at constant temperature (0 C.) and in darkness

Back 13

- maintain hibernation cycle with slight discrepancy, but not very significant

Front 14

Cricket song

Back 14

-Evidence for exogenous rhythms and the zeitgeber (“timegiver”)
-in laboratory with constant light - song drifts from natural pattern with restored light-dark cycle - does not take long to go back to normal
-light = "zeitgeber"

Front 15

Loss of rhythm in the cricket

Back 15

-optic lobes are disconnected from rest of brain - becomes essentially random

Front 16

cellular/biochemical basis for bioclocks - fruit flies (drosophila)

Back 16

-gene expression and Tx and trans.
-cellular mechanisms - 2 genes responsible for coding for particular proteins: PER and TIM
-dawn...no PER or TIM trans, many PER/TIM protein complexes in nucleus, disintegrate as sun rises
-noon...absence of PER/TIM complexes, per and tim genes begin Tx RNA but no trans
-dusk...peak levels of per and tim RNA in cytoplasm produce high levels of PER and TIM proteins, initial binding of PER and TIM complex
-midnight...PER/TIM complexes occumulate in nucleus - stop production of per and tim cellular process linked to external event involved in circadian rhythm

Front 17

honey bees and bacteria (Rothenbuhler)

Back 17

-Some strains of honeybees
susceptible to bacterial infection that
kills larvae (American foul brood
disease)
-Non-hygienic strain
-Others are not susceptible
-Hygienic strain
-Hygienic behavior consists of two steps
-Uncapping the larval cell
-Removing dead larva from cell
-Crossing hygienic with non-hygienic yields a nonhygienic
phenotype (at the F1 level).
-Therefore gene(s) for hygienic behavior was/were
recessive.
-But how many genes are responsible?
-Took hybrids from F1 generation and backcrossed them with individuals from the hygienic strain
-If 1 gene were responsible for the difference in behavior, ½ of the progeny would be expected to be hygienic

Front 18

Benzer & Drosophila gynandromorphs

Back 18

-Gynandromorphs (= sex mosaic)
Produced by “ring-shaped” X-chromosome which
is unstable during first division
-“XX” tissues are female
-“XO” tissues are male (O=missing X)

Front 19

Gene manipulation studies

Back 19

-oxytocin and male recognition of females in mice

Front 20

PET-1

Back 20

-Gene called “PET-1” is removed or “knockedout”
in mice, the mice display a greater level of aggression as adults than do normal animals.
-PET-1 gene was active only in neurons in the brain that produced serotonin, a neurotransmitter important for influencing many neural circuits that control behaviors such as anxiety, aggression, perception,
learning, memory, sleep-wake patterns, and other emotions and moods.(People who do not produce enough serotonin can suffer from mood disorders like depression and anxiety.)

Front 21

Voles

Back 21

-Monogamous and non-monogamous voles differ in the distribution pattern of vasopressin (neuropeptide) receptors
-Matched brain sections from a monogamous prairie(left) and a non-monogamous montane (right) vole, displaying differences in vasopressin receptor
binding. The vole species also differ in mating induced
vasopressin synthesis and release in the brain. Vasopressin is both necessary and sufficient for the formation of pair bonds in male prairie voles.

Front 22

Tryon: genetics of rat intelliegnce

Back 22

-Selective breeding experiment
-Tested rats for maze running ability and bred good performers with good performers, poor with poor...
-by 7th generation there were split groups of smart and dumb.
-other people did not find the differences Tryon found - diff apparatus and objects.
-thought he was testing intelligence, but was only selecting for maze running ability in a specific maze.

Front 23

Effects of Environment on Performance - maze running ability

Back 23

-if raised in controlled environment (restricted or enriched) differences diminished.

Front 24

Learning

Back 24

-Learning is a specific modification or change of
behavior involving the nervous system that occurs as a result of experience with an external event or series of events in an individual’s life.
-Learning does not include:
-Maturation of nervous system
-Male puppy squatting vs. adult male dog “leg lift” urination behavior
-Muscle or nervous system fatigue
-Sensory adaptation
-Vision adapting from a bright to a dark room

Front 25

Categories of learning:
1. Habituation

Back 25

-Habituation involves the gradual fading of an unlearned response to a stimulus that proves to be safe or irrelevant. Likely the most primitive and universal form of learning.
e.g., snail retreating into shell

Front 26

Habituation in Marine Snail, Aplysia (Kandel)

Back 26

-Gill retraction
•Nervous system composed of 18,000 neurons
•Gill withdrawal controlled by 1 ganglion containing 6 motor
neurons and 24 sensory neurons
•Habituation involves change at synapses between sensory and motor neurons (less neurotransmitter released)
•After few hours response returns.

Front 27

Categories of learning:
2. Sensitization

Back 27

-Sensitization involves showing a response to a previously irrelevant
stimulus because something relevant occurred shortly before.
-present octopus with a crab and it goes to it and eats it and it reacts the same with a neutral object
-present octopus with an object that shocks it and it withdraws and will do that with a neutral object right after it.
=sensitized.

Front 28

Categories of learning:
3. Classical conditioning
Pavlov (1849-1936)

Back 28

-Changes in the stimuli that elicit behavior:
•US e.g., food
•UR e.g., salivation
•CS e.g., bell
•CR conditioned
response
A STIMULUS (CS) CAN COME TO SERVE AS A CUE THAT
A REWARD (US) IS ABOUT TO OCCUR. (CONTINGENCY
BETWEEN STIMULUS AND OUTCOME)
-General findings
Strength of conditioning depends upon:
1. Consistency with which US follows the CS
2. Amount of time between the US and the CS (sooner the better!)
3. Relevance or strength of the US to animal at time presented but does not depend upon the nature of the CS

Front 29

Predispositions to learn
(“programmed” learning)
John Garcia (1966)

Back 29

-Study involved two groups of rats
-One group exposed to bright light and a sound (click) when
animals drank water from spout in cage (visual and auditory).
-Other group drank water sweetened with saccharin (taste).
-Each group divided into halves
-One half received electric shock (pain) after drinking.
-Other half received X-rays (does not hurt, but makes them
sick after several hours)
-avoided: light/sound-shock and taste- x-ray
-continued: light/sound- x-ray and taste-shock
-associations may or may not have been made

Front 30

Predisposition to Learn results for rats

Back 30

-Animals that received electric shock developed aversion to the water
associated with light and sound but not taste
-Animals that were made sick developed aversion to water associated with taste but not light and sound

Front 31

Categories of learning:
4. Operant conditioning
B.F. Skinner

Back 31

-Actions result in consequences:
reinforcers (positive or negative)
that influence the likelihood
of those actions occurring again.
-Also called “trial -and-error” learning

Front 32

Categories of learning:
5. Latent (exploratory) learning
Metzgar

Back 32

-Involves gaining experience, when there is no immediate reinforcer, that modifies behavior at a later time.
-white -footed mice - mice given chance to explore maze while another group just starts with activity
-given predator - animals given time to explore, evade predator better
-learn something about environment without reinforcement - prove later

Front 33

Categories of learning:
6. Observational (cultural) learning

Back 33

-An animal learns to do something by watching
what another is doing.
-blue tit milk bottle opening
-chimpanzee - “termite fishing”
-some say it doesn't happen in animals - not same culture as humans
-drawn to what environment has to offer
-accidently stumble on discovery - learn for self, not due to others
-are they capable of learning from one another? or just discover on own?

Front 34

monkey see monkey do?

Back 34

-Famous example: Japanese monkey “Imo”
-In 1953, a one and a half year old Japanese macaque, Imo, began washing off the sand from sweet potatoes by rinsing them in water before eating them. After four and a half years, 18% of the adult monkeys and 79% of the juveniles in the troop had acquired the potato washing technique.
-In 1956, Imo was observed separating wheat grains from sand by dropping them into water so that the wheat grains would float and the sand grains would sink. This behavior spread in a similar way (Kawai 1965; Watanabe
1994).

Front 35

M. Tomasello

Back 35

-do monkeys and apes really learn through observation?
-enhancement: drawn to location that stimulates you to make discovery
-imitation: do you have understanding of what you're doing? or are you just copying?
-could in theory distinguish actions without knowing purpose

Front 36

Macphail

Back 36

-does orangutan know what doing? no. but might learn consequences for actions but not know what doing.

Front 37

dolphins and imitation

Back 37

-understand gestures to mean things, but do they understand purpose?
-in natural habitat they must do lots of cooperation - hunting, protecting, males team up to attract females - ability to coordinate actions
-reinforcement to imitate humans=food, but if not reinforcement they would prob imitate one another
-there is a tendency for imitation - some forms of learning do not need immediate reinforcement - reward might be reinforcement

Front 38

M. Tomasello and apes capability

Back 38

-says exposed to tool and problem - so explore - trial and error - may be able to figure out best solution, but do not learn from one another
-won't imitate use, but will use tool how they want
-do not learn from eachother
-humans have ability to understand
-however he talked to kid before doing task

Front 39

Fair test of chimp ability?

Back 39

-negative results difficult to deal with
-caging of animals - not in normal, free environment
-role of environment is important in developing cognitive
-showing with diff. species

Front 40

Conformity to cultural norms of tool use in chimps
Whiten, Horner, and de Waal

Back 40

-done on social groups
-high ranking adult female taught to use lift/poke device to get food out of apparatus - rest of group allowed to watch "expert" use it - not allowed to mess with it over 7 days 20 minutes - all but 2/32 mastered with influence of expert - in society without expert none mastered - made alternative method of getting food, some got correct method but used the groups method = conformity bias.
-capability of animals of learning from others

Front 41

“Enemy” learning in blackbirds
E. Curio (1978)

Back 41

-experienced shown owl = predator but inexperienced do not see owl, but neutral like shoe however see fear reaction of experienced they then show this when exposed to shoe again

Front 42

Oystercatcher

Back 42

-hammers and stabbers
-hammer on weak point or stab it open slit and damage abductors - only use one strategy and mate with one of same strategy - not genetic, but acquired
-young birds stay with parents 2-3 yrs - because opening strategy so difficult, they need parents to model and practice to be able to do on their own - need confidence therefore need parents to only use one way.

Front 43

Categories of learning:
7. Insight learning
W. Köhler

Back 43

-The Mentality of Apes (1925)
-not based on things done/acquired before but just comes to you
-banana on string - what does chimp do? pile boxes and use sticks
-ravens and crows - steal fish
-Macphail - chimps need experience with objects before = trial and error - need to see animal solving problem for first time with no prior experience with tools
-Heinrich - food at end of string - pulls up meat not stones and then when strings crossed, it studies to figure out which to pull up and pulls one with meat

Front 44

How smart are crows?

Back 44

-A team of Oxford researchers arranged an experiment to find out whether Betty and Abel could pick the right tool for a job if given a choice. The
job: to snag a piece of meat from a tube using a wire.
The crows had a choice between a straight and a hooked wire.
Sure enough, Betty and Abel chose the hooked wire to snag the meat without any problems. But during the experiment, Abel, being bigger and dominant, stole Betty's hook, leaving her with only a straight wire to get her meat.
Instead of giving up, "she took the wire and wedged
the tip in a crack and bent it with her beak to produce a hook like the one that had been stolen," lab chief Alex Kacelnik says. "Betty then proceeded to get the food."
To make sure this wasn't a fluke, the team tested
Betty using straight wires only. Nine out of 10 times,
she made a hook.
Science: 297 (5583)

Front 45

Nut-Cracking Crows

Back 45

-throw nut into traffic at cross walks so they can collect food while crossing on

Front 46

Categories of learning:
8. Imprinting

Back 46

-Play.. a class of learning?
-Learning to hunt

Front 47

Programmed learning: bird song

Back 47

-Bird song functions
• Mate attraction
• Territorial defense
-Song vs. calls
Learning of song varies from species to species
• e.g., dove, white -crowned sparrow, canary
Sound spectrograph
• Visual depiction of sound
• Frequency (kHz.) and time domains

Front 48

White-crowned sparrow dialects
(P. Marler): evidence for learning

Back 48

-differences in song
-reared in different family = adopt foster = learning

Front 49

Bird song development
(W.H. Thorpe) - Chaffinch

Back 49

-early subsong - crude not as musical - experimenting
-late subsong - little more form
-plastic song
-full song - completely finished
-crystalization - when song reaches full form

Front 50

Bird brains and song

Back 50

-2 major production areas = HVc and RA

Front 51

Sex differences in brain structures involved in
song (F. Nottebohm)

Back 51

-In species where male sings: HVc and RA have greater volume and more neurons, e.g., canary
and zebra finch
-Also, in spring, HVc and RA volumes increase in males,
99% and 77%, respectively.
-“Close-ended” species have less neurogenesis in HVc and RA than “open-ended” species

Front 52

Song development in the
white-crowned sparrow (Marler)

Back 52

- 10-50 days of age - song young bird exposed to - brain receptive to sounds heard
-150 days (sexual maturity) - subset song phase - start singing

Front 53

W-c sparrow: hears normal w-c sparrow song AND song sparrow song during c.p.

Back 53

-Result: normal song as adult

Front 54

W-c sparrow hears song sparrow song

Back 54

-Result: “simple tune” as adult

Front 55

W-C sparrow hears nothing

Back 55

-Result: simple tune as adult

Front 56

W-C sparrow hears w-c song, but is deafened before subsong

Back 56

-Result: imperfect song

Front 57

Other results for w-c song development

Back 57

-W-c sparrow female hears normal male w-c song during c.p.: no song as adult
-BUT: inject her with testosterone as adult
and she sings very close to normal w-c song!
-And finally:
W-c sparrow hears backwards w-c song during c.p.: sings backwards!

Front 58

Challenge from Baptista & Petrinovich (1984-5)

Back 58

-strawberry finch next to cage of young white crowned sparrow - songs are very similar

Front 59

West & King – song learning in a
brood parasite

Back 59

-Females prefer the songs of isolate reared males … why?
-Brown-headed cowbird (male)
-song = innate
-males cluster around female and sing song - dominance - male (dominant) will attack other males who are trying to get female
-subordinate males drift away from song so dominant male will not attack
-female prefers pure form of song

Front 60

Four ways evolution has been used to study behavior

Back 60

-Historical / phylogenetic approach
– Involves reconstructing the evolutionary history of the behavior. Attempts to find behavioral “homologies.”
-Testing adaptive value through experimentation
– Involves determining the adaptive value of the behavior.
-Comparative approach
– Relies on comparing species with similar ancestry, but living in different environments and/or comparing species with different ancestries, but living in similar environments.
-Predictive approach
– Involves setting up hypotheses derived from evolutionary theory and then testing them with behavioral data from extant species.

Front 61

peppered moth (kettlewell)

Back 61

-testing adaptive value through experimentation
-in areas with not much pollution - white form has advantage and vice versa.
-bird tested through pictures to see if it can locate moths - presses button if sees it.

Front 62

Comparative Method

Back 62

-relies on comparing species with similar ancestry, but living in different environments and/or comparing species with different ancestries, but living in similar environments.
-Darwin's finches - natural selection has shaped bills in accordance with diet.

Front 63

Peter & Rosemary Grant

Back 63

-Medium ground finch (Geospiza fortis) of Daphne Island
-In 1982 the larger species arrived on Daphne eating most
of the larger seeds and steadily pushing the smaller
finches to rely on smaller seeds.
-G. fortis birds with smaller beaks that did not compete
with the larger species did better and were more likely to
have surviving offspring. This led to more G. fortis with
smaller beaks.
-Drought in 2003-04 meant seeds of any kind were
scarce. All of the G. magnirostris and any remaining G. fortis with large beaks disappeared.
-The only birds to survive and produce offspring in
2005 were the G. fortis with smaller beaks. They could
exploit small seeds like those of the drought-tolerant
Optunia cactus.

Front 64

convergent evolution

Back 64

-distinct ancestry shared mobbing behavior

Front 65

divergent evolution

Back 65

-shared ancestry divergent behavior

Front 66

Crook (1964) : weaver birds of Africa

Back 66

-Studied 90 species of weaver birds
-Striking differences in coloration, social & sexual behavior, and feeding ecology among species.
-Crook’s approach was to search for correlations between these aspects of social organization and the species’ habitat
-males build
-programmed learning - not learning to build nest from scratch - learn to be proficient at what genes give them.
-entrance pointed down - deters predators,like snakes, and brood parasites (e.g. brown-headed cow birds, cuckoos)

Front 67

Crook’s findings: weaver birds of Africa

Back 67

- Group 1
– Forest
– Insectivorous
– Solitary nests
– Feed alone in large
territories
– Drab color
– Monogamous
- Group 2
– Savannah
– Seed eaters
– Nest in colonies
– Feed in flocks
– Males brightly
colored
– Polygamous
-Food abundance and distribution thought to be the main selective pressure: the
“driving force.”
-no data to make food dist and abundance conclusion, but sounds good.

Front 68

Jarman (1974): 74 species of African ungulates

Back 68

-Group I: smallest ungulates
•Body weight: 3-60 kg.
•Habitat: forest
•Diet: selective browsing, fruits, buds
•Group size: 1-2
•Reproductive unit: pair
•Antipredator behavior: hide
-Group II
•Body weight: 20-80 kg
•Habitat: brush, riverine grassland
•Diet: selective browsing or grazing
•Group size: 2-12
•Reproductive unit: male + harem
•Antipredator behavior: hide, flee
-Group III
•Body weight: 20-250 kg
•Habitat: riverine woodland, dry grassland
•Diet: graze or browse selectively
•Group size: 2-100
•Reproductive unit: male territories
•Antipredator behavior: hide in herd, flee
-Group IV
•Body weight: 90-270 kg
•Habitat: grassland
•Diet: selective grazing
•Group size: 150-1000
•Reproductive unit: defense of females within herd
•Antipredator behavior: hide in herd, flee, some hostility
-Group V
•Body weight: 300-900 kg
•Habitat: grassland
•Diet: graze unselectively
•Group size: up to 1000
•Reproductive unit: male
dominance hierarchy in herd
•Antipredator behavior: mass defense

-larger animals have microbes in stomach can help break down food - allows to eat poor foods - size can influence WHAT you can do with food.

Front 69

Intraspecific variation in social systems ...

Back 69

- Spotted Hyenas (H. Kruuk)
– Serengeti populations usually solitary and nomadic. Scavengers.
– Ngorongoro Crater populations live in large cohesive social groups that
defend territories and hunt.
- Larger more abundant prey.
– When prey is high on the Serengeti, hyenas will form social groups and hunt.
-facultative behavior - within species differences in social and diet.

Front 70

Flexible social systems:
hamadryas and gelada baboons

Back 70

-can live in enormous groups and very small groups - variations in single days
-at night animals cluster in large groups and socialize/groom before dark - spend night on rocky outperches as safety - dawn comes = hunger - move from safety area - single male and females he mates with and offspring - so small groups forage/hunt - then regroup at night - critical factor = food availability
-facultative behavior in regard to social systems

Front 71

Brain size among Cetaceans

Back 71

-some social and some solitary
-communication varies
-vary in body size along with brain size
how relate to diet?
-baleen whales - swim and collect
-dolphins hunt and need communication to catch food - would need larger intelligence

Front 72

Testes size and primate mating system

Back 72

-if breeding with more than 1 female and other males available = larger than gorilla who is only one mating with females of group

Front 73

Foraging “strategies”

Back 73

-Predictive method: setting up hypotheses derived from evolutionary theory and then testing them with behavioral data from extant species.
- If food is “clumped” in environment what route should animal follow searching for food?
- What items should it eat?
- How long should it stay in one area (patch)?
- Which patch should it visit next?
- Should animal defend resources from others?
-Natural selection should, over time, make animals
efficient at tasks critical to survival and reproduction.
“Optimality models” of behavior.

Front 74

Crows & whelks (R. Zach)

Back 74

-Coastal crows feed on whelks by dropping them from the air onto rocks below.
-Do the birds use a dropping height that minimizes the total energy expenditure in upward flight?
-Whelk size:
-number of drops per whelk vs. height of drop (meters) height of approx 5m would be good enough - beyond, do not get much added benefit and below, must do more work.
-crow does use efficient height to accomplish task
-programmed - imply genes
OBJECT!
-genes might be involved in selection for general learning ability enabling them to solve problems and flexibility in behavior - not necessarily selection for whelk dropping

Front 75

Starlings at the nest (A. Kacelnik)

Back 75

-The “economics” of foraging
-how many items should parent bring on each trip in order to maximize the rate of delivery of food to the nestlings?
-graphical solution: starling's foraging
-food items vs search time
-marginal value theorem - decreasing gain with additional effort
-add in travel time and project from point ideal point will be found on curve
-changes position of feeding apparatus after going through it - this changes where ideal point is - birds mimic the more efficient behavior - facultative behavior
-programmed? learning? combination? no one knows. do know starling is sensitive to changes and solves problem in efficient way.

Front 76

Dungfly copulation time (G. Parker, 1978)

Back 76

-females lay eggs in fresh dung - male finds - female comes - copulate in fresh dung
-if male leaves before she lays eggs - second male can come - 80% will go to second male - decided advantage - first male must hang around and defend her - "mate guarding"
-how long copulation occur? - proportion of eggs fertilized vs time spent copulating - curve of diminishing returns
-add in search and guard time - predicted 41 min observed 36 min - says copulating in optimal manner - critics say its off so that can't be ideal - is discrepancy meaningful?
-are other factors being ignored? female behavior? maybe males have not reached their optimal solution?
-observed - based on average not individual
-should look at how individual males are performing

Front 77

Pocket gopher burrowing behavior

Back 77

-make holes to put extra dirt out of tunnel
-how long should it be between tunnels? 3.1 m?

Front 78

African Golden-winged Sunbird: territoriality and nectar production

Back 78

-when should defend patch? - only when pays you to do so
-flowers do not produce maximum nectar all day - biological clock - some points more nectar than bird needs, so why defend and expend energy - when nectar production is very low, also does not pay for bird to defend and too little to recover with - when nectar production medium - territoriality, enough to defend, but not to share

Front 79

Evaluating optimality models

Back 79

- ADVANTAGES:
- Generate testable, quantitative predictions
- Assumptions need to be made explicit (e.g., for starlings: optimize the rate of food delivery)
- DISADVANTAGES:
- What if behavior does not fit prediction?
- What if animals are not optimally adapted? (environmental change; insufficient genetic variation)
- “Good enough” vs. optimal
- Assumption of genes “for the behavior”
- Constraints on optimality (e.g., junco feeding)

Front 80

Criteria of Sociality

Back 80

-number of animals that come together
-length of time group remains together
-amount of time spend in social behavior
-reciprocal communication
-division of labor or "roles" in the group
-overlap of generations and parental care
-aid-giving : "altruism"

Front 81

Some benefits of sociality

Back 81

-anti-predation (increase flock, decrease predator success)
-increased feeding efficiency and information sharing
-facilitation of reproduction
-increased competitive ability
-division of labor
-energy efficiency
-social transmission of information
-combinations of these

Front 82

costs of sociality

Back 82

-increased competition for resources
-increased predation pressure
-increased transmission of disease
-african wild dogs: rabies, anthrax, canine distemper

Front 83

W.D. Hamilton’s “selfish herd”
hypothesis (1971)

Back 83

Origins of sociality are “selfish”: initially animals
derive a benefit from being next to others simply
because it reduces the likelihood that any one
individual will be captured.

Front 84

V.C. Wynne-Edwards
(1906 -1997)

Back 84

- Animal Dispersion in Relation to Social Behavior
(1962)
- animals “self-regulate” their populations through
social behaviors.
- for benefit of species
- case for “group selection”, the view that animals
sacrifice personal survival and fertility to control
population growth, i.e., for the good of the group as
a whole
- for Wynne-Edwards, animal behavior such as territoriality, dominance
hierarchies, and grouping in large flocks (epideictic behavior) were devices for
the control of population size.

Front 85

Levels of selection

Back 85

A. individual
B. kin
C. group selection

Front 86

Why group selection (usually) won’t work …. (Williams: Adaptation and Natural Selection, 1966)

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-By generation 14, over 99% of the population will be producing 3 offspring.

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David Lack
(1910-1973)

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- 30+ year study of Parus major (great tit)
– reproductive patterns
– studied the factors controlling numbers
in natural populations

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Clutch size in great tits

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-Size vs. number...
-Average weight of nestlings decreases with clutch size
-Survival of offspring is related to weight at fledging
-Experimental increase in clutch size
-Adult survival decreases with size increase

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J.B.S. Haldane
(1892- 1964)

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-While in a pub, Haldane was once asked if he would risk death by drowning to save his own brother. ‘No,’ replied Haldane, ‘but I would to save two brothers or eight cousins.’
- Wright’s coefficient of relatedness, “r”
r = probability that any randomly selected allele in
a focal individual has copy (identical by descent) in the related individual.

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W.D. Hamilton (1936-2000)

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– 1964 Journal Theoretical Biology paper
– Kin selection:
- The selection of genes due to an individual’s promoting the survival and reproduction of relatives (other than offspring?)
who possess the same genes through common descent.
– Inclusive fitness:
- The sum of an individuals own fitness** plus all its influence on fitness of relatives other than direct descendants (i.e., offspring).
** Fitness: the contribution to the next generation of one genotype relative to the contributions of other genotypes.

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Hamilton’s kin selection rule

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rB – C > 0
r = coefficient of relatedness of donor to recipient
B = benefit gained by recipient
C = cost to donor