BE Midterm Deck

Question 1

Tinbergen’s four “whys”

Answer 1

i. Causation (mechanism) – in terms of immediate proximal mechanisms
ii. Development/ontogeny – concerned with genetic and developmental mechanisms, patterns of growth and learning
iii. Adaptive advantage or function – increasing reproductive success (survival value), focus of behavioral ecology
iv. Evolutionary history or phylogeny – concerned with how the behavior came to be through natural selection

Question 2

Proximate & ultimate explanations

Answer 2

– are different types of explanations of behavior
• Proximate – how and individual comes to behave this way over its lifetime
• Ultimate – factors influencing adaptive advantage and evolution. Why/how the individual evolved to have this behavior

Question 3

Norms of reaction

Answer 3

Phenotype varies with environment in a particular, systematic way. A pattern of phenotypic expression of a single genotype that varies across a range of environments
• -e.g. E. coli bacteria turn lac operon on or off based on the presence of lactose in the environment, but the likelihood it is on or off at a particular moment depends on environmental history. Also the moths that get very different coloration depending on what food type was available when they were larva (helps them camouflage)

Question 4

Group selection

Answer 4

– natural selection operates not on the group level, but the individual level.
• -Lion and Langur monkey infanticide example: males kill infants because it benefits their own genetic fitness, although it’s not great for the species because it reduces individuals., - cheaters/ operates too slowly, this would never work

Question 5

Heritability

Answer 5

– On average, individuals tend to resemble their parents more than other individuals in the population (Darwin, but he didn’t know about genes), -genotype is heritable, the ability to exhibit a certain norm of reaction is heritable (although the variation within the norm of reaction is not)
• eye color is extremely heritable, height is somewhat heritable, but also dependent on environment, -see seger nd, who talks about continuum

Question 6

polyphenism

Answer 6

a polyphenic trait is a trait for which multiple, discrete phenotypes can arise from a single genotype as a result of differing environmental conditions. (e.g. honey bees: there is no genetic difference between queens and workers. Difference in environment is that queen is fed royal jelly from an early age)
Hrdy, citing MJ West-Eberhard, “Nothing is genetically determined in the sense of determined by genes alone. No gene is expressed except under particular circumstances… it is a kind of biological illiteracy to talk about a gene for anything other than a particular protein molecule.”
– term “biological mother” no good

Question 7

Phenotypic variation

Answer 7

– phenotypic plasticity (for a given genotype there are many phenotypes), could be random, which is how it is different from polyphenism

Question 8

Scramble vs contest competition

Answer 8

o scramble is when individuals in a group (or multiple groups) all have equal access to a resource and simply exploit it as much as they can
• this lowers the rate of return for everyone
- WGS/BGS von Schaik
• ideal free distribution resource lends itself (individuals are equally likely to encounter resource/resource is evenly distributed)
o contest is when individuals (or groups) compete for resources
• there will be a winner and loser and the winner gets way more than if it was scramble, but has to address costs of contest
- WGC/BGC von Schaik
• despotic distribution resources lends itself to this because these resources are more easily defendable (tend to be patchy)

Question 9

• Female bonded groups

Answer 9

– Wrangham realized that relationships among males or between males/females is most closely linked to distribution of females, but for female/female relationships ecological conditions directly come into play (access to food), so there are advantages to forming bonded groups in situations esp. where resource is rare and defendable
o Benefits: predation avoidance, information
o Costs: depleting patches quicker net gains go down
o But there were some problems with applying the model (4 cases against)
• Many non-FB sp also in groups, comp. for food inc. w/ group size, comp. btw group < comp. w/in group, declining birt rates as group inc.
• Van Schaik came in with refined definitions of types of comp…

Question 10

• Between group vs within group competition

Answer 10

– van Shaik – recall 4 figures relating dominance rank to net food intake, relates to group size
o BGC – found to be less strong than WGC – being dominant still advantageous, but very important to keep the group size up to compete better against other groups
o WGC – dominance rank very important, the smaller the group, the better because less competitors

Question 11

• “member’s rule” vs “joiners rule”

Answer 11

– recall the graph that plots mean per capita return rate with group size, consider return rate for individual, climbs w/ group size, but peaks at certain n
o members rule- maximize rate of return by exluding too many joiners
• more motivated to exlude depending on where in curve
o joiners rule, increase gain by joining group
• but only if curve is above individual intake line
o bring in Blurton-Jones to discuss costs and benefits to both joiners and members in terms of allowing access to groups (e.g. members will defend against joiners if the cost of defending is less than the drop in rate if joiner joins group)
o also see curves provided by B-J.

Question 12

• optimization

Answer 12

– highest return rate given costs and constraints present
o ordinary/general – just get as much as you can given constraints
• e.g. optimal diet maximizes mean return rate (profitability = E/Δt, eg calories/handling time)
o frequency dependent – depends what others are doing
• hawk-dove game: payoff depends on the strategy of opponent
o two classic models of optimal foraging theory
• diet breadth optimizes resource types (calories is maximized currency)
• marginal value theorem optimizes time (time is currency trying to maximize)

Question 13

• encounter rates

Answer 13

– diet breadth model – how often a resource is found during search (items found/Δt)
o might dictate whether or not to utilize a certain resource
• given low-profitability/high-encounter or high-profitability/low-encounter, the trade-off is whether to handle the lower resource or keep searching for the higher resource

Question 14

• currencies

Answer 14

– what is being optimized
o a hypothesis about the costs and benefits impinging on the animal
• e.g. bees energetic costs and benefits are much more important than predation risk
o currency examples: calories, reproductive success (over season/lifetime), like the equivalent to utility in game theory
o currency for maximum benefit would be like “maximize rate of energy delivered to nest for starlings, or rate of fertilized eggs for dung flies

Question 15

• adaptive function

Answer 15

– increases reproductive success (survival value/fitness)

o THE one of Tinbergen’s 4 whys that takes priority in questions of behavioral ecology

Question 16

• economic defendability

Answer 16

– the cost of defending something versus letting others have access to it
o question of whether it is worth defending
• e.g. territories, group admission/size

Question 17

• despotic distribution/hierarchy

Answer 17

– van Shaik – competition within groups, those that are more successful in defending resoures against others become dominant
o resources must be defendable
o despotic distribution is BGC (resources patchy, certain groups control resources and defend against others)
o hierarchy is WGC (some individuals in group get more access)

Question 18

• polyphenism

Answer 18

– a polyphenic trait is a trait for which multiple, discrete phenotypes can arise from a single genotype as a result of differing environmental conditions.
o Implies a norm of reaction.
• e.g. honey bees: there is no genetic difference between queens and workers. Difference in environment is that queen is fed royal jelly from an early age
o Hrdy, citing MJ West-Eberhard, “Nothing is genetically determined in the sense of determined by genes alone. No gene is expressed except under particular circumstances… it is a kind of biological illiteracy to talk about a gene for anything other than a particular protein molecule.”
• term “biological mother” no good

Question 19

• optimal group size

Answer 19

– members/joiners stuff

Question 20

• public vs private goods

Answer 20

– tolerated theft model
o if it is defendable, it’s a private good, if not it’s public (question of whether anything is actually a private good, could think of these as two ends of a continuum)
o -exludability v subtractability matrix
• excludability: how easy it is to keep others from using it (high: a fruit tree, low: leaves)
• subtractability: one user’s use subtracts from what is useable to someone else (high: food, low: NPR)

Question 21

• infanticide by male langurs

Answer 21

– case against group selection

Question 22

• prey (diet breadth, optimal diet) model

Answer 22

– do you handle or keep searching? Yes or no?
• Charnov ’76 for equations
• Post-encounter
o goal of model: maximize overall rate
o decision: yes/no
o tradeoffs: search/handle
o model forager has complete knowledge of encounter and return rates

Question 23

• resource ranking

Answer 23

– ranked by post encounter return rate (no search time)

Question 24

• mean net rate of energy gain

Answer 24

– what optimal diet maximizes
o perhaps better measured in other ways than calories (nutrients)
o varies with group size

Question 25

• ideal free distribution

Answer 25

– it is costless to move from one place to another
o scramble competition
o resources not defendable (opposite of despotic distribution)

Question 26

• complete information (foraging models)

Answer 26

– the idea that the forager knows the full variation, encounter rate, and profitability
o profitability and encounter rate of resources is known by forager

Question 27

• profitability

Answer 27

energy/handling time – E/h

o prey types defined by profitability

Question 28

• prey vs patch choice

Answer 28

– address the random encounter assumption with prey model, give that up with patch model
o think of this in terms of the historic sequence of ideas in the discipline
• resource encounter is random (MacArthur) v patch encounter is random (Charnov brought in the consideration of how resources are diminished on a curve rather than just available at a constant rate, and then not)

Question 29

• marginal value theorem

Answer 29

– stay or go
o decision: how much can you get by staying how long?
o Tradeoff: stay in patch or travel to new patch
o Assumes: diminishing returns
o E.g. starling food load (what is beak load that maximizes overall rate?), dungfly time in copula
o Recall slope of tangential line as relates to travel time (travel time in –x, search time in +x, load in y)

Question 30

• opportunity cost

Answer 30

– alternatives that are forfeited
o eg: warning colorations in moths/caterpillars
o eg: conspicuousness v crypsis: male guppies mate more but are more prone to predation

Question 31

• Tinbergen’s four “whys”

Answer 31

o	Causation (mechanism) – in terms of immediate proximal mechanisms
o	Development/ontogeny – concerned with genetic and developmental mechanisms, patterns of growth and learning
o	Adaptive advantage or function – increasing reproductive success (survival value), focus of behavioral ecology
o	Evolutionary history or phylogeny – concerned with how the behavior came to be through natural selection

Question 32

• Nutrient constraints

Answer 32

– more than just calories is needed in OFT
o Eg: Ache resource choices
• provided crisp falsification by showing that neither men nor women maximize their mean rate of resource gain
• so perhaps it’s not just maximizing energy returns, but instead depends a lot on specific nutrients needed
- fat and protein my be worth more per calorie than carbohydrates

Question 33

• A “prey type”

Answer 33

– different prey have different profitability

o Think of Charnov and the diagram with triangles

Question 34

• “perfect Pleistocene baby”

Answer 34

– Hrdy –
o the perspective of the perfect baby from the mom’s point of view
• able to be left unattended so she can go forage
o from the baby’s point of view, it would never want the mom to go away
• always the baby wants the be the center of attention
o so neither player gets their way all the time, conflicts of interest

Question 35

• frequency dependent payoffs

Answer 35

– payoff depends on other’s strategies

o hawk-dove game

Question 36

“hawk-dove game”

Answer 36

frequency dependent (also a good example of why group selection doesn’t work, if everyone plays dove…)

Question 37

ESS

Answer 37

• a strategy which, if adopted by a population of players in a given environment, cannot be invaded by any alternative strategy that is initially rare
  o An ESS is an equilibrium refinement of the Nash equilibrium. It is a Nash equilibrium that is “evolutionarily” stable: once it is fixed in a population, natural selection alone is sufficient to prevent alternative (mutant) strategies from invading successfully
  o The theory is not intended to deal with the possibility of gross external changes to the environment that bring new selective forces to bear.
  o ESS in Hawk-Dove is mixed (for cost of fighting > value of resource)
  • Unless you add a mixed “bourgeois” strategy, in which case, that becomes the ESS
  • Or, if payoff values change, such as if value of a resource is higher than the cost of fighting, then Hawk becomes ESS

Question 38

• “tolerated theft”

Answer 38

– all about economic defendability

Question 39

• phenotypic gambit

Answer 39

the way in which behavioral ecology (specifically ESS models) ignore the underlying genetics and assume all phenotypes are possible

Question 40

Wynne-Edwards (1962)

Answer 40

observed that populations to do not grow continuously, so a process must regulate growth. He thought group selection accounted for it, i.e. territoriality, dominance hierarchies, fertility rates were mechanisms for regulating population size.

Question 41

G.C. Williams (1966)

Answer 41

reproductive competition within groups usually stronger than between groups

Question 42

Lack Hypothesis

Answer 42

Lack hypothesized that 8-9 eggs/clutch is the size that maximizes mom’s number of surviving offspring per clutch.
-however, observations showed a smaller clutch size, so why?
-2 hypotheses to address the difference
lifetime v per brood succes: nat selection will maximize lifetime, not per brood reproductive success
taking into account females paying “full cost” (that of egg producing/laying), predicted optimal clutch size goes down (see chick/egg/inducing experiment)
-recall the figure (x=clutch size, y=costs or benefits) where optimal clutch size over lifetime is shown to have the largest distance from curve of clutch size (benefit) to adult mortality line (cost)
-variations from year to year show individual optima, case against good of group
- recall graphs relating life expectancy (future RS) to realized fecundity (current reproductive effort)

Question 43

sugden

Answer 43

• banknote game

- spontaneous order

Question 44

Wrangham

Answer 44

• wanted to find theories for the ecological determinants of social relationships (for primates)
  
  • came up with idea of female bondedness (later extrapolated by von Schaik)
    
    • FB groups will form in presence of patchy resources