Test 2 (incomplete but I gotta study something)

Logical Argument on Why Genes Influence Behavior

genes code for proteins used in structure or regulation, and proteins influence behavior

Genes are effected by ____

the environment (social & Ecological) and behavior

Behavior is effected by ____

genes and the environment (social & ecological)

Environment is effected by ____

behaviour

Evidence for Genetic Basis of Behaviour

Inbreeding, Artificial Selection, Hybridization, Molecular Genetics

Inbreeding

selective mating of closely related individuals. Reduces heterozygosity, different alleles become fixed in different inbred lines

• used to explore the effect of one variable

Adam Miklosi

studied paradise fish larvae, research on antipredator behavior. Two inbred strains studied after 30 generations, larvae showed different predator recognition behaviors. Behavioral differences attributed to genetic factors

Heritability

a statistical measure of the extent to which a trait is influenced by genes. Ranges from 0 to 1 (0.5 indicates 50% of observed variation attributed

Artificial Selection

humans decide which animals will reproduce, choice is based on desired behavioural traits (physical or behavioral).

EX: domestic Dogs

Tolman

“bright” vs “dull” rats study:

• Bright rats were good at navigation, dull rats were not

• mated lines of Bright and Dull mice

• found that “brightness” was not transferable

Lynch

studied normal mice vs. genetically altered mice that couldn’t build nests. Found that both genetics and environment impacted behaviors

Hybridization

Cross individuals with different expressions of the same underlying behavioral trait

eg: agressive x submissive

Complete dominance

the phenotype of the heterozygote is indistinguishable from that of the dominant heterozygote

incomplete dominance

the phenotype of the heterozygote is intermediate to the two homozygotes

Marla B. Sokoloskwi

Studied foraging behavior in fruit fly larvae. Two strains of foraging behavior: Rovers (move more in a patch) and sitters (move less), by crossing the two strains found that 75% of F2 generation was rovers, rover is a dominant allel.

Calling Behaviour in crickets

males produce call to attract females and are species specific. In the lab hybrids can be produced: hybrid males produce calls that are intermediate to parentals in frequency and duration, hybrid females preferentially orient to intermediate calls → shows genetic control with incomplete dominance

Molecular Genetics

enhances our understanding of the relationship between genes and behavior. Revolutionized in the last quarter century

mutagens

chemical, biological, or physical agents that alter DNA sequences

Quinn conditioned behavior in fruit flies

Studied test tubes of flies and odors, one odor paired with electric shock, flies were then averse to the stimuli. Shows associative learning

Recombinant DNA

precise experimental method for determining the effect of a particular gene on behavior. Once a gene is identified and located, it can be cloned and inserted into another organism’s genome, its effects can then be observed.

Circadian Rhythms in fruit flies

fruit flies show a 24 hour rythm, but some individuals are arrythmic viia a mutation. Gene therapy restores the 24 hour rythm

Social Behaviour in Voles

differences in the response to AVP are due to differences in the distribution of V1a receptors, small changes in these receptors’ genes will have a large effect on social behaviour. 

Adaptive Behaviour

evolutionary framework for studying behaviour for non-adaptive and maladaptive traits via observation, comparative and experimental methods

Darwin’s Definition of Evolution by Natural Selection

1. a trait must exhibit natural variation

2. some of that variation must be heritable

3. must be a struggle for existence

4. different variants of the trait should confer different probabilities of survival

Adaptive Basis of Behaviour

behaviour has a genetic basis that is subject to natural selection

→assume behaviour is adaptive

Adaptation

a trait that allows its bearer to survive and reproduce better than competing individuals that lack the trait

Fitness

a measure of an individual’s relative success in propagation its genes into the next generation via the production of decedent kin that survive to reproduce

inclusive fitness

a measure of an individual’s relative success in propagating it’s genes into the next generation via the production of descendant and non-descendant kin that survive to reproduce → W.D. Hamilton

cooperative Courtship in wild turkeys

Less fit males team up with dominant males to improve mating chances by defending territory. Displays inclusive fitness as helping kin (brothers) boosts the shared genetic shared genetic success

Non-adaptive traits

a characteristic of an organism that does not improve its ability to survive or reproduce

maladaptive traits

a trait that is more harmful than helpful, preventing an organism from adapting effectively

non-adaptive traits and maladaptive traits are expressed due to ____

• domestication

• context-dependence

• developmental anomaly

• disease/pathology

• parasitism (induced changes in behaviour)

Gene flow causing aridland spider maladaptive behaviour

? Gene flow from wetter regions introduces traits that are not suited for dry environments. These imported traits reduce survival or reproduction in arid conditions → gene flow can spread non-benifical traits when environments differ

Non-adaptive or maladaptive traits are velated via:

• selectively neutral behaviours

• conflict between natural and sexual selection (irish elk antlers were too big for traversal between trees)

• linkage between loci

• pleiotropic gene effects

• evolutionary time lags

Coevolution

reciprocal adaptations in interacting species due to natural selection imposed on the other species →evolutionary arms race

Red Queen Hypothesis

Van-Valen: animals must constantly evolve to maintain the same state of adaptation relative to their environment

adaptive infanticide

Maladaptive in most cases, however it is also:

• Resource Exploitation: reduced competition for resources

• Resource Competition: decreases number of competitors

• Parental Survival: increases parents chances of survival and future reproduction

• Sexual Selection: allows mother to quickly become sexually receptive, enabling mating with a new male

3 empirical approaches to understanding the Adaptive Basis of Behaviour

Observational, Comparative, Experimental

Observational Approach

an empirical approach to understanding the adaptive basis of behaviour wherein, animals are observed in their natural setting to gain insight into the adaptive basis of behaviour

Tinbergen’s black-headed gull work

eggs shells in nest attract predators that eat chicks. The black headed gull will remove shells from the nest 30 minutes after → the delay appears to be maladaptive, however the delay is to reduce neighboring gulls from eating chicks (a wet chick takes seconds to consume, but a dry one takes minutes)

Comparative Approach

an empirical approach to understanding the adaptive basis of behaviour wherein members of the same species are studied in different environmental conditions

Barash’s study of social behaviour of marmots

studied several species of marmot social systems and growing season. Found that with increasing elevation and decreasing growing season length selects for increased sociality 

Problem with comparative Approach

• based on correlation

• another variable may underline increased social behaviour (eg: predation rather than food scarcity)

• coloniality and sociality impart antipredator benifits

Experimental Approach

experimenter proposes a hypothesis for the adaptive function of a behaviour. Involves manipulate some aspect of the animal or its environment to test that hypothesis

adaptive head colour in Gouldian Finches

has 3 head colours that coincide with domination in social interactions. Red dominated black, red + black dominate yellow. When head colour was manipulated it had no effect on dominance

Optimality Theory

accounts for costs and benefits of a trait. Evolved traits represent an optimal balance between benefits and costs

optimum point on a Graphical Model of Optimality

when benefit is high and cost is low

common measurements of Optimality

season reproductive success, as well as time/energy budgets

Territory

a fixed area defended against rivals for a period of time. Related to food, shelter, mates, and may change in breeding or non-breeding seasons

Benefits of holding a territory

• guaranteed access to resources

• enhanced acquisition of mates

• reduced transmission of disease

• reduced predation

Costs of holding a territory

• increased energy/time expenditure

• enhanced risk of injury or death (competition and predator risk via displays)

• lost opportunity to exploit shifting resources

Resource attributes influence the economics of territoriality

1. resource abundance

2. resource distribution (space and time)

3. degree of competition for resources

Resource Abundance

a resource attributes influence the economics of territoriality that involves the correlation between less resources being available the less of a likelihood that a species will be territorial

Resource Distribution

a resource attributes influence the economics of territoriality that involves the incidence of territoriality increases with clumping of resources

Competition for Resources

a resource attributes influence the economics of territoriality that involves the increase of competition increases costs of defense, decreasing the incidence of territoriality

Relationship between Optimality and Territoriality

diminished benefits/increased costs may prevent the formation of territory however individuals can maximize net gain by optimizing their location/size/time that they hold a territory

Optimization in Rufous Hummingbirds

Defends territories around patches of flowers over the course of its winter migration. Accomplishes maximum energy gain via trial-and-error adjustment of territory size.

Frequency Independent Models

optima calculations are independent of frequency of behavior seen in other individuals. Recognize that fitness payoff of a given behavior is contingent upon what others are doing

Game Theory

models in which the optimum strategy is contingent on the frequency of behavior of others. Individuals ‘play’ against each other and “winning” is equated to fitness

Game Theory in Crickets

Two types of crickets: callers (produces signalling sound to attract mates) and satellites (hover around callers and intercept females). Callers have a higher success in mating but a higher risk of predation, while satellites have a lower success in mating but a lower risk of predation → strategies will reach equilibrium

Evolutionary Stable Strategy (ESS)

a set of strategies that, once adopted by a critical proportion of the population, cannot be replaced by other strategies

Nash Equilibrium

a stable state in a game where no player can improve their outcome by changing their own strategy if all other players' strategies remain the same

Origin of an Evolutionary Stable Strategy

each individual consistently plays one of the possible strategists so that the relative proportion of pure strategists in the population remain stable. Then each individual varies its strategy, playing each with a certain frequency.

ESS in Male Side-blotched lizzards

3 genetically determined colour polymorphs that each display a different reproductive strategy with same fitness payoff. The predominant colour fluctuates annually (Orange, then blue, then yellow then back to orange)

payoff matrix

formally states fitness payoffs to individuals playing all possible strategies

Hawks versus Doves

Hawks are aggressive; continue to fight until seriously injured or opponent retreats

Doves show aggressive displays, but always retreat rather than fight

Payoff Matrix Equations (A + B payoff relationship)

Payoff Matrix: A vs. B

	A (Opponent)	B (Opponent)
A	(Resource value - injury cost) / 2	Resource cost (if A wins)
B	0 (if B loses)	(Resource value / 2) - Display cost

• then tally from left to right row for fitness payoff

Payoff Matrix Equations (Proportion of A and B)

• A → p[(resource value - injury cost)/2] + (1-p)[resource value]

• B → p[0] + (1-p)[(resource value / 2) - display cost)

Where p is the proportion of A in a population

Asymmetries in Game Theory Models

1. Resource Hoarding Potential

2. Value of the resource

3. Arbitrary Asymmetries

Resource Hoarding Potential

an animal's inherent ability to win a physical fight if one were to occur

Game Theory Model Asymmetry in Funnel-Web spiders

females engage in territorial battles over productive web sites and employs conditional strategy: if an intruder is larger than the resident, the resident will exhibit aggressive displays but never fight. If the intruder is smaller, then the resident will be aggressive

Winner Effect

where wining a fight increases the probability of future wins

Loser Effect

Where losing a fight decreases the probability of future wins

Game Theory Asymmetry in Resource Value

One player has private information about the resource's value that the other lacks

Game Theory Asymmetry in Bowl and Doily Spider

A virgin female lays 40 eggs after fertilization, after 5 minutes there are 10 unfertilized eggs so the occupying male aggressivley defends against rivals. After 7 minutes there are only 4 unfertilized eggs so the male switches to a dove strategy (aggressive displays but not fighting)

→ shows Asymmetry in resource value

Game Theory: Arbitrary Asymmetries

asymmetries that are not connected to RHP or resource value. Rules or social conventions for setting disputes amoung conspecifics. Eg: prior ownership

Prior Ownership as an Arbitrary Asymmetry in Hamadryas Baboons

In mating: a male is perceived as “owner” of female if allowed prior association. This is respected even if intruding male in dominant.

In feeding: if no prior ownership of item is given dominant wins, if prior access is given the dominant does not challenge

Value of refined game theory models

• enhance understanding of behaviour

• organize empirical findings

• generate testable hypothesis