Study Guide EEB 100 Final PDF

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Anne Cam EEB 100 Discussion 1I Study Guide – Animal Behavior Midterm Lecture 1 – Intro to Animal Behavior -

Behavioral ecology – evolutionary and ecological approach to the study of behavior

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Types of causes (complementary): o Ultimate causes – adaptive value or evolutionary history of a trait o Proximate causes – immediate reasons for a behavior (usually physiological)

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"Struggle for existence" – species normally produce more offspring than can survive, leads to natural selection

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Criteria for evolution by natural selection: o Variation among individuals o Heritable traits resulting from variation o Traits must affect survival and reproduction

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Types of selection: o Artificial selection – selective breeding by humans for certain traits o Direct selection – selection for traits affecting individual reproduction o Indirect/kin selection – selection for traits in individuals that help relatives reproduce 

Coefficient of relatedness (r) – probability that two individuals share an allele due to common ancestry (0 if unrelated, 0.5 parent/offspring, etc)

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Explains evolution of eusociality, because sterile workers closely related to queen

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Hamilton's Rule – altruistic allele becomes more common if indirect fitness gained > direct fitness lost 

Equation: r b B> r c C where r b =coefficient of relatedness between individual and relatives,

B =number of relatives helped, r c =coefficient of relatedness between parents and offspring,

C =number of offspring not produced -

Types of fitness (fitness = number of gene copies passed on): o Direct fitness – reproductive/genetic success of an individual (measured in number of offspring that live to reproduce) o Indirect fitness – genetic success of altruistic individual (measured in number of relatives that live to reproduce) o Inclusive fitness – direct fitness plus indirect fitness

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Behavioral strategy – inherited behavior that is one of many alternatives affecting direct fitness o Adaptive behavior – behavior that increases direct fitness more than other available alternatives o Maladaptive behavior – behavior that reduces direct fitness more than other available alternatives 

Usually due to evolutionary lag time (environmental changes too fast for affected species to develop necessary mutations, requires generations)

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Can persist if adaptive in other situations, otherwise will disappear over time

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Eusociality – social system consisting of a specialized sterile caste working for reproducing members o Social insects (ants, termites, etc) and even vertebrates like naked mole rats

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Altruism – behavior that lowers the helper's direct fitness but increases the recipient's (usually relative's) direct fitness o Still selfish, because helper's indirect fitness increases – higher chance of similar genes being passed on

Lecture 2 – Behavioral Ecology, Evolution of Altruism and Social Behavior Chapter 2 -

Darwin puzzle – trait that appears to reduce individual/direct fitness (appears maladaptive), but is actually adaptive o Ex. Eusociality appears to be a Darwin puzzle

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Eusociality – social system consisting of a specialized sterile caste working for reproducing members

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Natural selection – process by which better-adapted organisms survive

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Types of selection: o Artificial selection – selective breeding by humans for certain traits o Direct selection – selection for traits affecting individual reproduction o Indirect/kin selection – selection for traits in individuals that help relatives reproduce

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Types of fitness (fitness = number of gene copies passed on): o Direct fitness – reproductive/genetic success of an individual (measured in number of offspring that live to reproduce) o Indirect fitness – genetic success of altruistic individual (measured in number of relatives that live to reproduce) o Inclusive fitness – direct fitness plus indirect fitness 

Inclusive fitness theory – important thing is the offspring that survive to reproduce (that would otherwise not have survived) thanks to extra help

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Altruism – behavior that lowers the helper's direct fitness but increases the recipient's (usually relative's) direct fitness o Still selfish – individuals give up direct fitness for an indirect fitness gain

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Hamilton's Rule – altruistic allele becomes more common if indirect fitness gained > direct fitness lost o Equation: r b B> r c C where

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r b =coefficient of relatedness between individual and relatives,

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B =number of extra offspring produced,

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r c =coefficient of relatedness between parents and offspring,

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C =number of offspring not produced by helper

Theory of descent with modification – (Darwin) modern traits evolved from changes to ancestral ones

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Monogamy vs. polyandry o Monogamy most likely ancestral

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Important in evolution of sterile workers in species such as social insects

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As long as queen has only one mate, offspring are full siblings whose indirect fitness will increase by assisting the queen altruistically

o Polyandry evolved later to improve genetic diversity (disease resistance) -

Effect of social conflict/"policing" on altruism o Encourages altruism because chances of improving direct fitness are low o Ex. Better policing in ant colonies leads to less worker reproduction; opposite also true

Chapter 3 -

Social behavior – animals living together and cooperating o Benefits must exceed costs for behavior to be adaptive

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Mechanisms of evolution o Kin selection – explains cooperation among relatives o Direct reciprocity – explains cooperation among non-relatives

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Types of social interactions among individuals (and effects on fitness): o Cooperation – A and B help each other right now 

A (helper) and B both gain direct fitness immediately

o Postponed cooperation – A eventually gains access to a resource controlled by B because of prior help 

A (helper) gains direct fitness eventually (because of helping B)

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B gains direct fitness immediately (from A's help, and from controlling resource)

o Reciprocity – B directly pays back A for its prior help, but after a delay 

Not necessarily related (reciprocal altruism if related)

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A (helper) gains direct fitness eventually (paid back by B over time)

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B gains direct fitness immediately (from A's help)

o Maladaptive altruism – A sacrifices lifetime inclusive fitness to help B 

A (helper) loses both direct and indirect fitness (loses overall inclusive fitness)

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B gains direct fitness (from A's help)

o Adaptive altruism – initial direct fitness loss for A results in its gaining indirect fitness 

A (helper) loses direct fitness but gains indirect fitness (overall inclusive fitness rises)

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B gains direct fitness (from A's help)

o Spite – A reduces own reproductive success to harm B (getting back at noncooperative individuals) 

Both A and B lose inclusive fitness

o Deceit and manipulation – B exploits/manipulates A (helper)

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A (helper) loses inclusive fitness

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B gains inclusive fitness (from exploitation of A)

Prisoner's dilemma – predicts reciprocal behavior should never evolve if only a one-time interaction o Two parties, A and B both in prison and interrogated separately o If A defects, gets freedom while B gets max prison time (ex. 10 years) o If A and B cooperate (tell same story), both get minor payoff (ex. 1 year prison) o If A and B both defect, both get punished (ex. 5 years prison) o Either party is better off defecting/taking from the other

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Multiple social interactions in animal species allows for cooperation to evolve o Remembering who helped them last time, and only helping those individuals o Back-and-forth cooperation adds up, exceeds the one-time payoff of defection

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By-product hypothesis – assuming a maladaptive trait can be adaptive in certain situations

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In general, higher relatedness = more cooperation o Helping others usually occurs when there is little chance of increasing direct fitness ex. Seychelles warblers will help when dispersal unfavorable, will stop helping and disperse when habitat favorable o Conditional strategy?

Lecture 3 – The Evolution of Communication -

Communication – transfer of information between two or more individuals o Requires a signaler and a receiver o More complex system in social animals

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Types of communication o Intraspecific communication – within a single species o Interspecific communication – between different species 

Prey to predator 

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Predator to prey 

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Ex. "Baiting" or deceiving prey

Humans and animals 

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Ex. Warning coloration

Domestication

Different communication methods/signals o Visual – colors o Auditory – vibrations, songs, echolocation o Tactile o Electrical o Chemical – pheromones

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Sensory exploitation hypothesis – certain signals evolved because they activate preestablished sensory systems o Ex. Whistling moths possess ancestral ability to detect ultrasonic signals, used to evade bats 

Males now use the system to their advantage by producing ultrasonic signals to attract females

o Color preference in animals like fish based on foraging ability 

Brighter yellow/orange/reddish colors from carotenoids indicate better ability of opposite sex to obtain these rare foods

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Novel experiments – testing animals' responses to artificial stimuli o Artificial attributes always produced stronger responses in females

o May be due to retention of ancestral preferences, although attributes were lost over time -

Panda principle / Principle of Imperfection o Evolution of new adaptations/behaviors occurs only from existing traits o Traits never have to be perfect, just need to be sufficient for given niche o Ex. Panda's "thumb" evolved from wrist bone and not completely new digit (actual thumb already adapted for running in carnivorous ancestors)

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Parthenogenesis – asexual reproduction (no fertilization occurs) o Ex. Whiptail lizards lay eggs that become females

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Adaptationist hypothesis – tests whether a given trait is adaptive (improves individual/direct fitness)

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Main example – evolution of pseudopenis in female hyenas o Submission hypothesis o Social-bonding hypothesis

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Threat displays – allows conflicts to be settled without physical fights o Adaptive because both sides save energy and time, also prevents injuries o Fighting most likely when both sides are evenly matched (no clear dominance)

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Honest signals – signals that give true indications about the abilities/traits of an individual o Saves both sides from injury, wasted time or energy when one opponent is clearly stronger o Helps organisms find prey, mates o Natural selection acts against mimics/dishonest signalers (over time, individuals which can detect dishonesty will increase) 

"Cheater" individuals with dishonest signals tested for and often punished (e.g. submissive wasps painting dominant pattern onto their faces)

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Evolution of deception o Mimicking dangerous species (some octopi), deceiving prey to make them easier to catch (Photuris female firefly), etc. o Illegitimate signaler – deceives receivers using a generally advantageous signal

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Reduces species fitness, but does not eliminate the direct fitness benefit of that particular signal

o Illegitimate receiver – usually predators taking advantage of prey signals -

Explanations for evolution of deception o Novel environmental theory – evolutionary lag time in which advantageous counter-mutations have yet to arise o Net benefit theory – sensory mechanism that is exploited in deception is still useful overall for a species 

Ex. the pattern of flashes recognized by Photinus males is used by the Photuris female (different species) to attract, capture and eat them

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Photinus males still possess the sensory system for recognizing such flashes (don't evolve evasiveness to it) because overall, still helps them reproduce – losses due to deception are few in comparison

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Convergent evolution in signals can occur o Many songbirds have a similar alarm call (vocal range) because common predators like hawks can't hear it

Lecture 4 – Avoiding Predators and Finding Food -

Every behavior has fitness benefits and costs o Fitness benefit – positive effect a trait has on reproductive success (number of offspring that survive to reproduce) o Fitness cost – negative effect a trait has on survival + reproductive success o Note: fitness, reproductive success and genetic success often used interchangeably

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Distraction hypothesis – social harassment of predators e.g. mobbing o Benefits: protects young (eggs, chicks, etc) o Costs: large energy expenditure

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Adaptation – heritable trait that spreads in a population through natural selection, displacing other alternatives o Adaptive value – a given trait's contribution to fitness

o Trait never has to be perfect, only needs to fit the individual's niche (also natural selection only acts on preexisting traits) -

Parsimony – choosing simplest scientific hypothesis that still fits the given evidence o ex. a phylogeny with the least amount of evolutionary changes is the more likely one o Occam's Razor – "When faced with two possible explanations, the simpler one of the two is the one most likely to be true"

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Two types of evolution o Convergent evolution – unrelated species develop similar traits, due to similar environments and selection pressures o Divergent evolution – related species (recent common ancestry) develop different traits, due to different environments and selection pressures

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Social defense – shared vigilance and communal defense mechanisms o Dilution effect – forming extremely large aggregations, which reduces the chance of any one individual being caught by predators o Fighting back in groups

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Social mutant – individual which tries to protect itself at the cost of others in its population (e.g. using another as a "living shield")

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Selfish herd – a population in which self-interest > group interest o Caused by social mutants being prevalent o Individuals use each other as living shields – everyone ends up competing for the safest position (usually in the center)

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Game theory – decision making is treated as a game o A given strategy can work well under one scenario, but may not in others (and against other strategies) o In evolution, winning = getting more of your genes passed on than your opponents

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Cryptic behavior – makes prey less detectable by predators, thus increasing direct fitness o Cryptic coloration – camouflage o Benefit: evading predators

o Cost: finding right background to hide against (not always ideal) -

Conspicuous prey behavior o Defense mechanisms activate when under attack (e.g. making noises) o Aposematic coloration – obvious bright coloring indicates unpalatable prey – predators learn to associate the two after trial and error 

Honest signal

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Other honest signals – gazelles "stotting," indicating they have lots of energy to escape and will be hard to capture

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Optimality theory – adaptations with best cost-benefit ratio (highest net fitness) will persist o In general foraging efficiency leads to better reproductive success o Should also account for predation risk – animals will sacrifice short-term caloric gain for long-term survival and reproduction (even if reproductive success decreases)

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Frequency-dependent selection – fitness of one strategy is a function of the other's frequency o When one strategy is very common, it becomes adaptive (increases fitness) to adopt the rarer strategy o Ex. African cichlid fish – when right-oriented jaws more common, prey learn to expect attacks from the left side, so it becomes more advantageous to have leftoriented jaws (attacks not expected from the right side) o Frequency of phenotypes oscillates around an equilibrium point

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Conditional strategy – individual's ability to change behavior based on conditions encountered o In a dominant-submissive situation, submissive behavior results from making the best out of a bad situation o In the absence of dominants, submissives will revert to dominant behavior (b/c more advantageous)

Lecture 5 – The Evolution of Habitat Selection, Territoriality and Migration -

Types of decisions made by animals (each with costs and benefits): o Habitat choices o Whether to defend a territory o Staying in/moving to a new area o How to use habitat

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Ideal free distribution theory – individuals decide how to distribute based on freedom to migrate and fitness gains of chosen habitats (in other words, individuals move around and evaluate habitat quality, settling where reproductive success is maximized) o Key assumptions: 

Habitat suitability decreases as population density increases

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All individuals settle in most suitable (ideal) habitat possible

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All individuals in a given habitat have the same expected fitness (free)

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If highest-quality habitat is full, lower-quality habitat will be chosen – fitness increases possible because lower competition

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Free movement discouraged when individuals are territorial 

Benefits of territoriality – can use resources without competition

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Costs – large energy expenditure

Territoriality – claiming a certain habitat and defending it from competitors o Benefits: 

Monopolizing access to good resources

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Spacing benefits (being spread out) – ex. parasite avoidance

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Site fidelity – gain familiarity with available resources, refuges)

o Costs: 

Large time/energy expenditure for aggression

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Risk of injuries during fights

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Risk of losing territory to a better competitor

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Risk of predation

o Benefits must outweigh the costs for territorial behavior to be adaptive

o Otherwise, peaceful coexistence (usually during non-mating season and resource abundance) o Does resident always win? 

Asymmetry hypothesis – more value placed on territory (and more willing to defend) if familiar with it and its available resources; thus intruder ...