we can think of behavior as what an animal does and how it does it , …

25
We can think of behavior as what an animal does what an animal does and how it and how it does it does it, … including nonmotor components of behavior such as learning and memory {changes of “state” that influence future behavior - like hunger & fear} If we consider the development {ontogeny} of any behavioral trait, we find a series of environmental {“nurture”} and genetic {“nature”} influences. Behavioral ecology Behavioral ecology views behavior as an evolutionary adaptation to the natural ecological conditions {and social environment} of animals. Natural selection favors behavior that enhances survival and reproductive success. The debate about biological evolution and human culture remains The debate about biological evolution and human culture remains heated. heated. The spectrum of possible human social behaviors may be circumscribed by our genetic potential, but this is very different from saying that genes are rigid determinants of behavior. This is at the core of the debate about sociobiology.

Upload: dewitt

Post on 12-Jan-2016

41 views

Category:

Documents


0 download

DESCRIPTION

We can think of behavior as what an animal does and how it does it , … including nonmotor components of behavior such as learning and memory {changes of “state” that influence future behavior - like hunger & fear}. - PowerPoint PPT Presentation

TRANSCRIPT

Page 1: We can think of  behavior  as  what an animal does and how it does it , …

We can think of behavior as what an animal doeswhat an animal does and how it does itand how it does it, … including nonmotor components of behavior such as learning and memory {changes of “state” that influence future behavior - like hunger & fear}

If we consider the development {ontogeny} of any behavioral trait, we find a series of environmental {“nurture”} and genetic {“nature”} influences.

Behavioral ecologyBehavioral ecology views behavior as an evolutionary adaptation to the natural ecological conditions {and social environment} of animals. Natural selection favors behavior that enhances survival and reproductive success.

The debate about biological evolution and human culture remains heated.The debate about biological evolution and human culture remains heated.The spectrum of possible human social behaviors may be circumscribed by our genetic potential, but this is very different from saying that genes are rigid determinants of behavior. This is at the core of the debate about sociobiology.

Page 2: We can think of  behavior  as  what an animal does and how it does it , …

A simple path model of the evolution of behavior: (Boyd & Richardson1985)

zygotes

Genes ‘nature’

Sociallearning ‘nurture’

vertical transmission

Ecol. &SocialEnv.

horiz

onta

l tra

ns

It is very difficult to tease apart the effects of genes, esp w/o carefully controlled experiments.

Parents

Otherroles

sele

ctio

n

Other complications include ‘maternal effects’ ex: womb environment

Even w/ experiments, difficult if genes & env ‘interact’ - diff genotypes react to diff env’s differently: (effects not additive)

Parents children

and gene-environment correlations (parents influence social env)

Page 3: We can think of  behavior  as  what an animal does and how it does it , …

B.F. SkinnerB.F. Skinner, … developed the theory of "operant conditioning" {and ‘the Skinner box’}

http://www.forerunner.com/forerunner/X0497_DeMar_-_Behaviorism.html

BehaviorismBehaviorism originated with the work of John B. WatsonJohn B. Watson, an American psychologist … not concerned with the mind … only with behavior. In this way, men could be studied objectively, like rats …

Watson's work was based on the experiments of Ivan PavlovIvan Pavlov …… he rang a bell as he fed some dogs … Pavlov then rang the bell without bringing food, but the dogs still salivated. They had been {classically} "conditioned" to salivate at the sound of a bell.

E. L. ThorndikeE. L. Thorndike … "law of effect” … a given behavior is learned by trial-and-error, and is more likely to occur if its consequences are satisfying.

{Three fundamental ideas in behaviorism, that justified the arbitrary use of rats & pigeons as models of humans were that 1. humans (& other animals) are born with minds that are blank slates … 2. we are conditioned by experiences written on our blank slates, and 3. the conditioning process is the same ‘general process’ across all species.}

Page 4: We can think of  behavior  as  what an animal does and how it does it , …

Comparative PsychologyComparative Psychology & Ethology

Various animals mature ‘pre-programmed’ instincts‘pre-programmed’ instincts and they come ‘programmed to learn’‘programmed to learn’ (‘innate school marm’ - Lorenz) with different programs to attend to and learn different thingslearn different things at different ‘critical’ times and places.

‘‘Biological constraints’Biological constraints’ include … a pigeon will learn to peck a button to get food but it cannot be trained to peck a button to avoid electric shocks; …. however, it can learn easily to hop on a lever to stop an electric shock …Animals are especially prepared to learn taste aversionstaste aversions, associating nausea with stimuli associated with novel foods. However, John Garcia showed how preprogrammed rats are:they quickly associate taste w/ x-ray induced nausea, but not w/ electric shocks, but “ “ “ light & sound w/ electric shock, but not w/ x-ray induced nausea

EthologyEthology (Lorenz, Tinbergen & von Frisch) began treating behaviorsbehaviors (& learning) as adaptive traitsadaptive traits, like other bits of phenotype - wings, guts, eyes etc. … that have phylogeny, ontogeny, proximate mechanism & ultimate functionphylogeny, ontogeny, proximate mechanism & ultimate function.

Imprinting: learning that is limited to a ‘sensitive period’ in an animal’s life; generally irreversible.

Page 5: We can think of  behavior  as  what an animal does and how it does it , …

(Alcock 1998)

Bird song is a great illustration of the interplay of genes and environmentin the development of behavior.

Songbirds (oscines) are ‘programmed to learn’ (but not all programmed same)

Deafened sub-oscines (eg woodpeckers, hummingbirds) develop normal but simple songs. Deafened oscines (songbirds) sing completely degraded complex songs (Konishi, 1965).

*Not

e: th

is fi

g sh

ows

‘mai

n ef

fect

s’ o

f G &

E,

but i

t doe

sn’t

show

a G

xE ‘i

nter

actio

n’

*

Page 6: We can think of  behavior  as  what an animal does and how it does it , …

Mundinger PC. 1995. Behaviour-genetic analysis of canary song: Inter-strain differences in sensory learning, and epigenetic rules.Animal Behaviour 50: 1491-1511.

Abstract:The relation between genes and canary song learning preferences was analysed with two experiments. A breeding experiment used inbred canaries, Serinus canaria, reared in isolation from adult songs to uncover differences in the song learning of Roller canaries, Border canaries and their hybrid.

Given a choice of Roller & Border canary tutor song,all Rollers selectively learned from the Roller song, all Borders learned only from the Border song, but the hybrids learned from both tutor songs.

… Cross-fostering showed that early experience with an alien-strain female parent does not noticeably affect the development of canary song learning preferences …

The study provides empirical evidence for … gene-inherited mechanisms that guide cultural transmission.Some epigenetic rules for canary song learning are described.{ex: selective learning of sharp down-slur, or high-pitched vibrato}

Page 7: We can think of  behavior  as  what an animal does and how it does it , …

Pupil (subject)

Holdin memory

Subsong: babble rememberedsong parts

Plastic phase:‘perfect’ varioustutor song parts

‘Crystallize’ one full song,

discarding alternatives

tuto

rs

After hatching, males selectively memorize

conspecific song components

Final song matcheslocal dialect of neighbors

(by selectively discarding less similar songs in memory)

Selectively learn potential songsat home, one year

Settle on actual song dialectnext year, after dispersal

Page 8: We can think of  behavior  as  what an animal does and how it does it , …

Diff pops develop and maintain diff traditional dialects:

Apparently arbitrary;persist because

young immigrantsmatch

older resident males

“culture”

Page 9: We can think of  behavior  as  what an animal does and how it does it , …

Nelson et al. 1996. The capacity for song memorization varies in populations of the same species. Animal Behaviour 52: 379-387

Males from the migratory ... Z. I. oriantha, learned significantly more tutor material, from more tutor song types, and produced more song types … during vocal rehearsal from a rich tutoring regime {2 long blocks of 16 pairs} than from a lean regime. {14 short blocks of 2 pairs}Males of the sedentary nuttalli race learned similar amounts from rich and lean regimes.

We argue {should “hypothesize”} that a migratory annual cycle introduces greater uncertainty into where a young male will breed for the first time, and that this has favoured the capacity to memorize more songs during the early sensitive phase for song memorization in migratory populations.

G x E interaction

Abstract:To compare the song learning capacity of migratory and sedentary birds, we contrasted the responses of males from two different populations of the white-crowned sparrow to rich and lean regimes of early tutor experience. …

Page 10: We can think of  behavior  as  what an animal does and how it does it , …

Bell et al. 1998. Song learning and vocal tradition in Nuttall's white-crowned sparrows.Animal Behaviour 55: 939-956

Abstract:We investigated song sharing and dispersion of song types in the wild in a marked population of the non-migratory Nuttall's white-crowned sparrow …

The songs of fathers, their male progeny (sons), and the neighbours of the sons at recruitment sites were analysed spectrographically and compared …

The songs of 14 of 16 sons clustered with their neighbours rather than their fathers' songs, confirming that song matching of neighbours is an integral component of territory settlement by juveniles. … {intrasexual selection}

Ex. #5 Ex. #1

Page 11: We can think of  behavior  as  what an animal does and how it does it , …

Bird: yygm bymp ppom

a sharedsong type

Territory tenure in song sparrows is related to song sharing with neighbours, but not to repertoire size. Beecher et al. 2000. Animal Behaviour 59:29-37.

Our longitudinal study of 45 song sparrows followed from their first year on territory showed that the number of songs a bird shares with his neighbourhood group is a better predictor of lifetime territory tenure than is his repertoire size.

Yea

rs o

n te

rrito

ry

Page 12: We can think of  behavior  as  what an animal does and how it does it , …

Chilton G, Lein MR 1996. Songs and sexual responses of female white-crowned sparrows(Zonotrichia leucophrys) from a mixed-dialect population.Behaviour 133 173-198

Abstract:Some researchers have suggested that female songbirds mate with males singing local song types in preference to males singing dialects from more distant populations. {intersexual selection} ...

We studied captive female white-crowned sparrows from a population in which two song types were equally common, …Subjects were captured as adults, and the song type of the mate of each was known. Treated with estradiol, females gave sexual displays in response to playback of conspecific male song.

… Individuals solicited no more strongly to their male's song type Individuals solicited no more strongly to their male's song type than to the other local song type.than to the other local song type.

Our results suggest that female white-crowned sparrows female white-crowned sparrows do do notnot base their choice of mates on base their choice of mates on dialectaldialectal variation in male song variation in male song and that it is unlikely that mate choice decisions based on song dialect promote the genetic isolation of dialect populations.

Page 13: We can think of  behavior  as  what an animal does and how it does it , …

However, local dialectsdialects apparently not important to female mate choicenot important to female mate choice;

rival repulsion is an important rival repulsion is an important function of song dialectsfunction of song dialects

(intrasexual selection)

Generally, species-typicalspecies-typical song song is important in mate attractionis important in mate attraction

(intersexual selection).

Page 14: We can think of  behavior  as  what an animal does and how it does it , …

DialectsDialects apparently not important to female mate choice; But:

Fig 51-6. Female warblers prefer males with large song repertoiresrepertoires. Male sedge warblers with large repertoires attract females to pair with them earlier in the breeding season, than males with small repertoires. Males with large repertoires, as well as the females that prefer them, benefit from pairing early because breeding early tends to be more successful than breeding late in the season.

Page 15: We can think of  behavior  as  what an animal does and how it does it , …

Nestling growth and song repertoire size in great reed warblers: evidence for song learning as an indicator mechanism in mate choice.Nowicki et al. 2000. Proc. Roy. Soc. Lond. B 267: 2419-2424.

Female mate choice: dialects – no; repertoire size - yes

Abstract:Females of many songbird species show a preference for mating with males that have larger song repertoires, but the advantages associated with this preference are uncertain. We tested the hypothesis that song complexity can serve as an indicator of male qualitysong complexity can serve as an indicator of male quality because the development of the brain regions underlying song learning and production occurs when young birds typically face nutritional and other stresses, so that song reflects how well a male fared during post-hatch development.song reflects how well a male fared during post-hatch development.

We used data from a long-term study of the great reed warbler (Acrocephalus arundinaceus)

to test this prediction, correlating two measures of nestling development with subsequent repertoire size of males.

A key prediction of this hypothesis is that variation in nestling condition should correspond to variation in the adult song repertoires of individuals.

ww

w.rom

acivica.net/cyberia/ riserva/cannar.jpg

Page 16: We can think of  behavior  as  what an animal does and how it does it , …

Nowicki et al.

These data support the idea that song may provide females with information about a male's response to developmental stress, which in turn is expected to correlate with indirect or direct benefits she might receive. {note “support the idea,” like “is consistent with” is generally not a powerful test}

We found that the length of the innermost primary feather, the length of the innermost primary feather, a standard measure of development, a standard measure of development, significantly predicted first-year repertoire size. significantly predicted first-year repertoire size. The relationship between repertoire size and body mass was nearly significant, in spite of the large variance inherent in this measure.

Page 17: We can think of  behavior  as  what an animal does and how it does it , …

http://www.nature.com/nsu/020429/020429-3.html

Early birds have big eyes.Birds that can see better in low light kick off the dawn chorus.

30 April 2002 NATASHA MCDOWELL

Birds with large eyes begin singing earlier in the morning than their small-eyed neighbours because they can see better in low light. The keen-sighted early birds probably do get the worms. Big eyes may help the hunt for breakfastBirdsong is an acoustic advertisement. Birds use it to attract mates and defend territory. But singing also alerts predators. So a bird does not sing before it can see well enough to spot approaching danger. Yet a bird also does not want to waste time crooning when the sun is high enough to search for food. The earlier it can see to sing, the earlier it can see to start foraging.

Thomas, R. J. et al. Eye size in birds and the timing of song at dawn. Proceedings of the Royal Society of London B, 269, 831 - 837, (2002).

Early bird: the robin starts singing over an hour before some of its neighbours.

Behavior is one part of an integrated phenotype, & it is coadapted to the rest of the parts of the body

Page 18: We can think of  behavior  as  what an animal does and how it does it , …

4 kinds of compensating benefits - not mutually exclusive:

1. MutualismMutualism: “pseudo-reciprocity,” immediately selfish: I’ll scratch your back and you scratch mine simultaneously.

I’ll groom you if you let me eat the tasty tics I find. Examples of cooperative hunting and market exchanges.

2. ReciprocityReciprocity: ultimately selfish but risky delay between cost and benefit: If you scratch my back now, I’ll scratch yours later. Common in humans but data on other animals is controversial.

3. Kin selectionKin selection: indirectly selfish: increase representation of genome in future through many more nieces & nephews, if slightly fewer own children. Haldane - Drown self to save 8 cousins? Hamilton’s ruleHamilton’s rule.

Some animals behave altruistically (unselfishly), in ways that appear to reduce the number of offspring they produce. Research is beginning to reveal how these behaviors are adaptive and how they could have evolved by natural selection.

Altruism:Altruism: donor pays cost, receiver gets benefit. Why do ‘do-gooders’ do good?Why do ‘do-gooders’ do good?What ultimate benefits compensate for the costs?

4. Group selectionGroup selection: is ultimately either kin-group selection, or mutualism.

Page 19: We can think of  behavior  as  what an animal does and how it does it , …

Experimental evidence for kin-biased helping kin-biased helping in a cooperatively breeding vertebrate.Russell & Hatchwell 2001. Proc. Roy. Soc. London B 268: 2169-2174.

Abstract:The widespread belief that kin selection is necessary for the evolution of cooperative breeding in vertebrates has recently been questioned. {cooperative breeding = helping others raise young}These doubts have primarily arisen because of the paucity of unequivocal evidence for kin preferences in cooperative behaviour. {It is very difficult to reject the alternative hypothesis that the behavior is mutualistic and just happens to involve kin, who just happen to be nearby}

Using the cooperative breeding system of long-tailed tits (Aegithalos caudatus) in which kin and non-kin breed within each social unit and helpers are failed breeders, we investigated whether helpers preferentially direct their care towards kin helpers preferentially direct their care towards kin following breeding failure.following breeding failure. continued …

Page 20: We can think of  behavior  as  what an animal does and how it does it , …

First, using observational data, we show that not all failed breeders actually become helpers, but that those that do help usually do so at the nest of a close relativethose that do help usually do so at the nest of a close relative. {kinship estimated by DNA fingerprint similarity}

This study provides strong evidence that kinship plays an essential role kinship plays an essential role in the maintenance of cooperative breeding in this species. in the maintenance of cooperative breeding in this species.

Second, we confirm the importance of kinship for helping in this species by conducting a choice experiment. {most unguarded focal nests predated, else eggs cross-fostered out to simulate predation; potential helper target nests have predator guards}

We show that (a) potential helpers do not become helpers potential helpers do not become helpers in the absence of close kinin the absence of close kin {r<0.25} and when given a choice between helping equidistant broods belonging to kin and non-kin within the same social unit, (b) virtually all helped at the nest of kin virtually all helped at the nest of kin {r=0.5}.

Page 21: We can think of  behavior  as  what an animal does and how it does it , …

The quest for cooperationcooperation is as old as evolution itself. In the Origin of Species, Darwin noted that natural selection cannot directly promote altruistic acts where individuals reduce their own competitive ability but increase that of others. Yet cooperation is abundant in nature.

LONELY

The standard explanations that have been developed for this include kin selection, group selection and reciprocitykin selection, group selection and reciprocity.

The essence of cooperation is captured by the public-goods gamepublic-goods game. Each individual of a group can decide whether or not to invest some money in a common pool. The common pool is increased by some amount and then equally distributed among all group members regardless of whether or not they made a contribution. The optimum outcome for the group occurs if everybody cooperates. But the temptation is to 'free ride'But the temptation is to 'free ride': those who don't contribute (defectors) always get a higher pay-off than cooperators who do contribute. If everyone defects, however, no one will enjoy the public goods. Self-interest is self-defeating! {“The Tragedy of the Commons”}This social dilemma threatens the success of public enterprises such as social security, the conservation of environmental resources or group defence against external threats.

Page 22: We can think of  behavior  as  what an animal does and how it does it , …

Notice that the well-known 'prisoner's 'prisoner's dilemma'dilemma' is a public-goods game for groups of two people.

player 2 c d

2 3 c 2 0

0 1 d 3 1

Two players w/ two tactics: cooperate, defect

play

er 1

Mutual cooperation beats mutual defection: 2 > 1 but there is a temptation to defect: 3 > 2 & fear of being made a sucker: 0 < 1 Cooperation is too risky in a single playCooperation is too risky in a single play

In repeated play w/ same partner: strategy tit-for-tattit-for-tat (conditional reciprocity) is, on average, a winning strategy.

Page 23: We can think of  behavior  as  what an animal does and how it does it , …

Evolution: The good, the bad and the lonely Hauert et al.4 proposed a new and surprisingly simple mechanism to surprisingly simple mechanism to promote promote cooperationcooperation.

Figure 1 Players in a public-goods game are represented as cells distributed spatially on a grid. {each individual/cell interacts w/ 8 neighbors}Cooperators are blue, defectors red and loners yellow. Players may change their strategy in each round of the game. For this simulation, all strategy updates are synchronous. Intermediate colours indicate players who have updated their strategies in the last round of the game. {note aggregation of tactics: “communities” of cooperators}

4.Hauert, C., De Monte, S., Hofbauer, J. & Sigmund, K. Science 296, 1129-1132 (2002). 5.Szabó, G. & Hauert, C. Phys. Rev. Lett. 89, 118101 (2002). 

Rather than allowing cooperation or defection as the only strategic alternatives, they added a third option — 'loners''loners', who do not participate in the game but instead receive a small, independent pay-off corresponding to a modest income from some self-sufficient occupation. … to a stable equilibrium among all three strategies. … instead of defectors winning the world, there is coexistence among cooperators, defectors and loners. In spatially extended games, as investigated by Szabó and Hauert5, voluntary participation is even more successful in promoting voluntary participation is even more successful in promoting cooperationcooperation than in well-mixed populations. {cooperators can avoid non-cooperators}

Page 24: We can think of  behavior  as  what an animal does and how it does it , …

A neural basis for social cooperation.Rilling et al. NEURON 35 (2): 395-405 JUL 18 2002

it may be the case that the observed activation is associated with positive feelings toward one's partner; … can result in feelings of trust and comradery that reinforce the cooperative act, superseding any conscious recognition that material gains will flow from mutual cooperation. This agrees with the everyday observation that we often behave altruistically toward others simply because we like them, {proximate mechanism?}not {?} because we consciously calculate that they are likely to reciprocate in the future. {ultimate function?}

Abstract:We used fMRI to scan 36 women as they played an iterated Prisoner's Dilemma Game with another woman to investigate the neurobiological basis of cooperative social behavior. Mutual cooperation was associated with consistent activation in brain areas Mutual cooperation was associated with consistent activation in brain areas that have been linked with reward processing: that have been linked with reward processing: nucleus accumbens, the caudate nucleus, ventromedial frontal/orbitofrontal cortex, and rostral anterior cingulate cortex. We propose that activation of this neural network positively reinforces reciprocal altruism, thereby motivating subjects to resist the temptation to selfishly accept but not reciprocate favors.

Page 25: We can think of  behavior  as  what an animal does and how it does it , …

Discriminating Discriminating cooperatorscooperators and and cheaterscheaters is important to stabilize is important to stabilize reciprocityreciprocity..

Abstract:… students were asked to rate the attractiveness of photo reproductions of Caucasian males. Each of the photo reproductions was presented with a fictional descriptive sentence giving information on the depicted individual's social status (high or low) and character (history of cheating, irrelevant information, or hist. of trustworthiness).

A week later subjects again rated photos-half repeated and half new- this time, without descriptions, Subjects were asked to report Subjects were asked to report which of the photos they remembered from the previous weekwhich of the photos they remembered from the previous week. …

the bias was mitigated when the face was presented as a person of high status;

… The results support the idea that we have evolved highly selective attention we have evolved highly selective attention and storage mechanisms for processing social informationand storage mechanisms for processing social information, and that both charactercharacter (cheating potential) and statusstatus are important features in the engagement of these mechanisms. {“social intelligence”}

Enhanced memory for faces of cheaters.Enhanced memory for faces of cheaters.Mealey et al. 1996.ETHOL. & SOCIOBIOL. 17:119-128.

The predicted bias - that subjectssubjects would preferentially recognize preferentially recognize faces initially presented as those of cheatersfaces initially presented as those of cheaters - was confirmed.