Comparative Animal Behavior Exam 2

What is sexual reproduction?

Production of offspring by the combination of gametes from two parents

What are the costs of sexual reproduction?

Losing 1/2 of genes, hard to be successful

What are the benefits of sexual reproduction?

Genetic diversity and recombination

What is anisogamy?

Gametes are not the same size

What factors contribute to reproductive asymmetry?

Females have larger gametes and gestation/lactation while males have less costs

What limits female reproductive potential?

Access to food

What limits male reproductive potential?

Access to mates

What are the aspects of Bateman's principle?

1) Females choose due to costs of egg production and limited reproductive success
2) Female choosiness translates into greater variance in reproductive success of males

What are simultaneous hermaphrodites?

Have both M/F parts at once (slugs)

What are sequential hermaphrodites?

Born as one sex but can change later on (clownfish)

What is intrasexual selection?

One sex competes for access to the other; usually males competing for females, favors traits that enhance competitive ability
- Explains size dimorphism, elaborate weaponry, and reproductive skews

What is sexual dimorphism?

Males and females differ phenotypically; often the result of intrasexual selection in males. Higher dimorphism correlates with higher skew in reproductive success

What are some indirect benefits males compete for?

Space and social status (elephant seals fight for dominance ranks)

What are the direct benefits males compete for?

Involves fighting for females or fertilization

What is sperm competition? Describe some components of it.

Sperm competition = form of post-copulatory competition
- 1st male precedence - copulation plug prevents more sperm from getting in (swallowtail butterflies)
- Last male precedence - common among insects, involves sperm displacement or removal
- Mate guarding
- Physical changes - sperm competition selects for morphological/physiological changes (male primates in polygynous systems have larger testes and produce more sperm and stuff)
- Forced insemination of another male - female receives both sperm (bed bugs)

What are the two types of alternative breeding strategies? Define them.

- Condition dependent - induced by environment (natterjack toads are chosen by volume of calls; when large males are removed the small males begin to call)
- Evolutionary equilibrium - heritable (male ruff mating strategies

What is intersexual selection?

Competition between males and females based on "attractiveness" to the opposite sex

Why do females get to be choosy?

The sex that invests more in offspring production has fewer reproductive opportunities, so they should be more discriminating and become a limiting resource for the opposite sex

Describe an example of sex role reversal.

Female jacanas defend territories and accumulate harems of males
Females weigh 60% more than males (dimorphism)
Lay multiple clutches each season
Males incubate clutches

Describe an example of direct benefits in intersexual selection.

Nupital gifts - scorpionflies give prey to potential mates and females choose based on the biggest prey received
Also things such as territory, parental care, and protection

Describe the good genes hypothesis.

Elaborated male traits may be indicators of heritable genetic quality (fitness)
Females select for increased offspring survival or reproductive success

What is the handicap principle in the good genes hypothesis?

Traits are expected to be honest signals in that there is a true cost to the elaborated trait that prevents cheaters

Examples of good genes hypothesis

Peacocks - mating success positively correlated with number of eyespots on trains; offspring of males with elaborate tails weighed more and survived longer
Rats - select for diversifying MHC of offspring

What does the Hamilton-Zuk hypothesis have to do with the good genes hypothesis?

Expression of particular male traits is associated with resistance to parasites or other pathogens (blackbirds having a brighter beak means greater resistance - carotenoids)

Describe the sexy sons hypothesis.

Females use indicators of male attractiveness to select among mates so the resulting offspring will be attractive to the next generation of females

What is Fisherian runaway selection?

Correlation between a trait and female preference
At some point trait evolves to be a burden and only benefit for female choice is that the sons will inherit the attractive trait
- Alone, does not address origin of female preference but positive feedback loop leads to runaway process after female preference evolves

What is sensory exploitation?

When female bias for a stimulus evolutionarily predates the male mating trait (e.g. primates like red things, trichromatic vision -> prefer red things, then preference for red coloration evolved after)

What are the two mechanisms of mate choice?

Pre-copulatory - actually choosing
Post-copulatory - cryptic female choice

What are the aspects of post-copulatory mate choice?

- Manipulating copulation duration - changes success rate of insemination
- Manipulating sperm storage
- Selective sperm use
- Ejecting sperm

How does variability in sexually selected traits persist over time if strong selection reduces heritability?

- Sexual selection is stronger under extreme conditions and may be relaxed in better times
- Interactions with other traits are constraining
- Mate choice often relies on multiple traits
- Counterbalancing natural selection for factors like protection against predators limits elaborateness of signal (frog yellow for mating and brown for anti-predator)

Why are the sexes in conflict? (3 reasons)

- Anisogamy
- Females select for quality and males select for quantity
- Differential investment - parental care is costly

What is monogamy?

One male and one female paired for at least a breeding season

What is social vs genetic monogamy?

Dad but not father
Extra-pair copulations = mating outside of relationship pretty much

What are the three hypotheses for why monogamy has evolved? (just list, other questions ask to describe)

- Necessity for paternal care
- Infanticide risk
- Mate guarding

Describe the paternal care hypothesis of monogamy

- Male reproductive success is greater when provide parental care to one brood compared to attempting to provide for many broods
- Likely when biparental care increases offspring survival and when seeking additional mates is costly
- Ex. father tamarins and marmosets help carry infants bc twins are hard to care/make milk for

Describe the infanticide risk hypothesis for monogamy

Males come and kill non-offspring babies :(

Describe the mate guarding hypothesis of monogamy

- Tradeoff between paternity certainty and more mates
- Likely when females are hard to find, females are intolerant of each other, and when females remain receptive (high risk of sperm competition)

What is polygyny? Describe the general bits and pieces like two bullet points

- Involves one male and multiple females
- Common among vertebrates

What are the four types of polygyny?

- Resource defense
- Female defense
- Scramble competition
- Lek

What is Environmental Potential for Polygyny (EPP)?

Spatial and temporal distribution of females or resources

What is resource defense? (two points + example)

- Males defend resource patches
- Female fitness depends on patch quality
- Ex. African cichlids (she spelled it wrong in the lecture notes lmfaooo)

What is the polygyny threshold model?

Identifies circumstances in which a female will gain more by mating with an already mated male than with a bachelor
- Ex. Lark Bunting - shade is limiting resource related to nestling survival

What is harem defense? (3 points + example)

- Females aggregate for their own reasons (protection usually)
- Males defend groups of females or harems
- Males have a short tenure
- Ex. Caribous, reindeer, Sika deer

What is scramble competition? (3 points + example)

- Females are widely dispersed or have very concentrated breeding period
- Costly for males to defend territories
- Impossible for males to monopolize mates
- Ex. Orangutans

What are leks? (5 points + example eek)

- Males cluster in small spot and display
- Males defend tiny area, but defend no resources
- Elaborate male displays
- High reproductive skew
- No pair bond
- Ex. sage grouse

What is polyandry? (1 point and example)

1 female, multiple males
- Ex. Grey foam nest treefrogs' eggs can be fertilized by 12+ males!

Why be polyandrous from a female perspective?

- Good genes; fertility insurance
- Material benefits
- Extra help
- Paternity confusion

Is social monogamy actually monogamy?

No, this includes EPCs and they are actually polyandry

Why be polyandrous from a male perspective?

Females will fight over males... idk what else to say here there really isn't much in the slideshow to work with

What is polygynandry? (2 points + example)

Two or more males have bonds with two or more females
- Numbers don't need to be equal
- Ex. acorn woodpeckers

What is promiscuity? (1 point + example)

Multiple females and males with no pair bonds
- Ex. chimpanzees, bonobos

What are the benefits of promiscuity for females? (4)

- Good genes; fertility insurance
- Material benefits
- Extra help
- Paternity confusion

What are the benefits of promiscuity for males?

- Get to father lots of offspring, but high reproductive skew

What is the big picture surrounding parental care? (3 points)

- Continuing issues of differential investment beyond gamete size
- Key factor determining mating system
- Adds significant time budget burden for those providing care

Why do we think parental care has evolved?

If care of young enhances survival of young enough to compensate for the reduction in production of young, then expect parental care to evolve

Describe the facets of no parental care (think of the to care or not to care table! 3 points + example)

- No contact with offspring after eggs are laid
- Benefits: free to mate more, no energy expenditure
- Costs: high levels of mortality
- Ex. Turtles

Describe the facets of care of laid eggs (think of the to care or not to care table! 3 points + example)

- Guarding and/or incubating eggs to hatching
- Benefits: Eggs have protection from predators/harsh conditions
- Costs: Energy expenditure, some mortality after hatching
- Ex. Seahorses

Describe the facets of care of young (think of the to care or not to care table! 3 points + example)

- Care of young after hatching/birth
- Benefits: Higher chance of offspring survival
- Costs: Very high energy expenditure, may not be able to mate for many years
- Ex. Mammals, birds

What is the concept of parental investment? (2 points)

- Any form of parental behavior that is likely to increase the survival and fitness of young AND decrease the parent's ability to invest in future reproduction
- Maximize lifetime reproductive success, not necessarily single bout of reproduction

Describe resource allocation in parental investment (3 points)

- Resources are finite
- Resources allocated between self and offspring
- Resources allocated among offspring

Give some examples of parental investment (5 total)

- Gamete provisioning
- Guarding eggs
- Guarding offspring
- Nursing
- Carrying

Why is Trivers 1972 considered a foundational paper? What's important about it?

- Parental investment increases exponetially with more offspring
- Females invest more
- The optimal number of offspring is lower for females than males

What are two aspects of the costs and benefits trade-off of parental investment?

- Current vs future reproduction
- Quantity vs quality of offspring
- Ex. as care increases (more offspring), less chance of surviving winter in willow tits

Who provides care? (Go over males, females, and both sexes)

- Males: common among fishes
- Females: common in mammals, most likely across entire animal kingdom
- Both sexes: can be equal or unequal; ~3% of mammals and 70% birds

What is the parent-offspring conflict theory?

Evolutionary framework for understanding conflict within families, rooted in genetic differences between parents and offspring

What is inclusive fitness?

Direct fitness + indirect fitness = total genetic contribution to next generation

What is the coefficient of relatedness?

Probability that a gene shared among the two individuals is identical by descent

What is differential investment in offspring?

Parents should maximize the number of offspring produced
Choose who to invest more in based on health (color of mouths in barn swallows dictates who gets fed)

What is the Trivers Willard hypothesis? Explain the logic behind it

Greater investment in sons in "good" times and greater investment in daughters in "bad" times
- Strong sons will impregnate lots of females
- Daughters are likely to mate at least once when times are bad
- Ex. First-time macaque mothers produce richer milk for sons but more milk for daughters

What does the insurance egg hypothesis entail?

Extra egg is laid for insurance, killed if 1 hatches first

Why is kin recognition beneficial?

- Parental care benefits increase as parental certainty increases
- Individuals sharing genes with relatives would benefit from recognizing kin and helping them

Why is offspring recognition costly and when should it evolve?

- Costly because need to develop and maintain sensory systems; potential for incorrect rejection
- More likely to evolve when benefits are high (ex. when parents frequently encounter non-related young) -> stronger selection

What are the three matching models for kin recognition?

- Familiarity
- Phenotype matching
- Recognition alleles (hormones)

What does the rule-of-thumb model entail for kin recognition?

Location? That's it ig

Why does kin recognition matter?

- Avoid inbreeding
- Evolution of altruism - behavior is costly to actor and beneficial to recipient

What is cooperation?

An outcome in which two or more interacting individuals each receive a Net benefit from their joint actions, despite possible costs

Why is explaining altruism/cooperation one of the biggest challenges in evolutionary biology?

In a mixed population of cooperators and defectors, the defectors get higher payout than cooperators

List the five evolutionary explanations for (Costly) cooperation (there's six if you're feeling spicy)

- Kin selection
- Direct reciprocity (reciprocal altruism)
- Indirect reciprocity
- Network reciprocity
- Group selection
* Bonus = byproduct mutualism

What is Hamilton's rule?

rB > C; provide help when the coefficient of relatedness times the benefits gained by recipient are greater than the costs to altruist in terms of future reproduction

What conditions favor the evolution of eusocial behavior (obligate altruism)?

- Haplodiploidy
+ Males develop from unfertilized eggs and are haploid
+ Females develop from fertilized eggs and are diploid
+ Females share more genes with sisters (r=0.75) than daughters (r=0.5)
+ Kin selection on indirect fitness -> better to help relatives than to breed yourself
- Inbreeding increases relatedness

Describe reciprocal altruism (2 points)

- Altruistic behavior will be a function of the probability that the recipient will reciprocate
- The cost of helping is offset by the likelihood of return benefit

What are the conditions for behavior to be categorized as altruistic according to Trivers 1971?

- Behavior reduces a donor's fitness relative to a selfish alternative
- Fitness of recipient must be elevated relative to non-recipients
- Donor performs behavior without expecting immediate benefit (aka not mutualism)
Also:
- A mechanism for detecting "cheaters" must exist
- A large (indefinite) number of opportunities to exchange aid must exist

Describe game theory in the evolution of reciprocity.

- Game theory = study of strategic decision making
+ "The study of mathematical models of conflict and cooperation between intelligent rational decision makers"
- John Maynard Smith applied game theory to biology to try to find evolutionary stable strategies

Just like.. describe the iterated prisoner's dilemma?

Incorporates T (temptation to defect), S (sucker's payoff), P (punishment for mutual defection), and R (reward for mutual cooperation)
Ties into game theory and how we weigh the decisions we make based on how we expect others to act in return
- Benefit from mutual cooperation, but gain more by exploiting cooperation of others
- One-off cooperation is NOt an ESS
- Stable cooperation can evolve without kin selection or mutualism if animals encounter the same individuals repeatedly

Describe how the predictions went for the vampire bat article!

- During treatment subjects received less food overall
- Bats that fed more non-kin in previous years had more donors and received more food during treatment
- For the "Food sharing with targeted donors would go down after treatment compared to pre-treatment", not supported by this study but could be possible over time; some went up and some went down

Why do female vampire bats with kin roost-mates help non-kin?

To establish connections - more donors when they need it

Are vampire bat donors within a group interchangeable?

No, it's not an easy swap for primary donor relationships

Is vampire bat non-kin food sharing easily explained by the iterated prisoner's dilemma?

No, this is a bit more complicated. Need to consider partner relationships, multiple types of investment, and multiple social bonds

What's up with reciprocal grooming in primates? Gimme some details

- Relationships are maintained through emotional bookkeeping
- Oxytocin levels are higher after grooming with social bond partners, regardless of kinship

What is indirect reciprocity? Give example?

- Cooperative behavior between two individuals that does not depend upon their direct interaction
- Information is gathered from third parties or indirect observation
- Helps explain evolution of cooperation in individuals with one-shot encounters
- Ex. Cleaner fish - clients (big fish) eavesdrop (watch on reef) and prefer good cleaners (that don't bite you)

What is byproduct mutualism?

When selfish behavior by one individual has an incidental, but beneficial spin-off effect for another individual performing the same act
- Ex. hunting

Describe network reciprocity.

- Population structure is not random
- Cooperators can form clusters where they can earn higher payouts than defectors
- Clusters form when they reap benefits regularly of interactions with the same individuals

What's up with group selection / Multi-level selection?

- Vero Wynne-Edwards proposed that natural selection acts on groups and that individuals could alter reproduction for the good of the group, but that's kinda just kin selection
- Then David Sloan Wilson said "Selfishness beats altruism within groups. Altruistic groups beat selfish groups. Everything else is commentary"
- So pretty much, selection on the lower level (within groups) favors defectors, and selection on the higher level (between groups) favors cooperators

What are polyadic interactions?

Dyadic = two
Polyadic = more than two

What's the difference between a coalition and an alliance?

Coalition = cooperative action taken by at least two individuals (or groups) against another individual (or group)
Alliance = long-term coalition
- In chimps, position in coalitionary support networks predicts paternity success
- In dolphins, females will run away sometimes while the males beef with each other

Define feeding vs foraging.

Feeding = consuming food
Foraging = act of searching for and acquiring food (more costs)

What are the kinds of decisions animals have to make when foraging?

- What to eat
- Where to eat
- How much to eat
- How much time to spend
- Share?

Describe what herbivores do and stuff. Just like everything you can think of

- They eat plants
+ Frugivores (fruit)
+ Foliovores (leaves)
+ Nectarivores (nectar)
+ Granivores (seeds)
- Can browse (up high) or graze (near ground)
+ Resource partitioning among ungulates
- Have to overcome plant defenses (chemical, mechanical)
-> Ex. Monarchs lay eggs on milkweeds and caterpillars are tolerant to toxins; transfer toxins to body for protection

Describe how carnivores do their thing (just say everything you can think of about them)

- Consume other animals
- Locating food can be harder - have to find mobile food/prey
- Predators -> active hunting; sit and wait; exploit prey signals
- Parasites

What's a sacrophage?

They scavenge or eat non-living organic matter