Animal Behaviour L26-32

• 1. Reduce time spent foraging
• 2. Feed in safer locations
• 3. Increase vigilance
• 4. Avoid detection
• 5. Deter attack
• 6. Deflect attack
• 7. Startle displays
• 8. Dodge attack
• 9. Fight back

• e.g. Golden-winged sunbird
• Forages only long enough to obtain energy to sustain itself
• Retreats to shelter of nest
• leaves shelter only when energy levels critical
• Increased foraging time when nesting

• e.g. American pika
• Subject to intense predation pressure by birds of prey
• Forage among boulders and rock slides that provide refugia from predators (birds of prey, not a weasel)
• Lactating females venture into open meadows

• Demonstrated that predation risk determines foraging area experimentally
• Modified habitat by creating narrow rows of rocks extending into meadows
• Under manipulated conditions, pikas readily exploited areas of lush forage
• - But remained in close proximity to the artificial refugia created by the rows of rocks

• Minnows distribute themselves relative to resource availability (resource matching)
• Minnows modify foraging location relative to risk of predator (yellow perch)
• Minnows assess predators and decide where to forage based on perceived risk (used hypoxic water)

• Robb and Abrahams suggest that minnows in nature may use hypoxic waters as a refuge from predators
• Studied by Kevin Hedges
• --> But can anyone see a problem with the "hypoxic refuge" hypothesis?
• predators may take prey by "darting" into hypoxic waters
• Perch can withstand over 1 min in anoxic water before showing signs of distress

Moving away from predator may not enhance safety

Predator inspection

The tendency of individuals to move toward a potential predator

• Particularly well known among fish
• - George (1960) mosquitofish
• - Milinski (1977) Stickleback
• - Pitcher (1986) - minnows
• - Dugatkin and Godin (1992) - guppies

• Approach benefits "inspectors" by:
• Providing information regarding predator
• Monitoring predator's movements
• --> a predator kept in sight cannot attack by surprise
• Deter attack (more later)

• Predators rely on the element of surprise to capture prey
• Once detected their success is diminshed

Organism(s) scanning their surroundings for potential predators (visual, chemical, auditory, etc.)

• Animals adjust the trade-off between foraging and vigilance relative to potential threat
• -> increase vigilance where threat is high, reducing their risk of being depredated

• e.g. Eastern chipmunk
• Spent more time foraging in "open" patches than in forest-covered patches
• - Increased time in open attributable to greater proportion of foraging bout devoted to vigilance
• Vigilance decreases probability of predation, but also diminshes short term energy gain
• Long term benefit of trade-off is access to patches

• Use of cover
• Crypsis: 
• - via physiological colour change
• - via choice of background

• e.g. leaf-curling spiders
• Forms tube fastened to center of web
• Remains inside tube avoiding detection but close enough to respond to prey in web

e.g. Veined octopus (Coconut octopus)

e.g. Squid, cuttlefish, octopi generate their own cover (e.g. ink). 

Might obscure chemical and visual field

Blending with background via evolutionary modification of colouration, markings, morphology and behaviour

• Two methods of achieving crypsis:
• i. Change appearance to match background (physiological colour change)
• ii. Choose background that matches your appearance

• e.g. cuttlefish
• System of chromatophores allows colour and pattern matching of substrate
• Musculature is extensive - stretch and contract cells to control pigment strength

• Breaks up body contours e.g. cuttlefish and zebras
• For cuttlefish, light filtering in water column with the disruptive colouration makes it difficult to ascertain the presence of cuttlefish

Used in ships

• Because light normally comes from above, the ventral surface of the body is in shadow, and stand out
• Animals my obscure that ventral shadow by having lighter coloured ventrum
• Darker dorsum may also reduce detection from above
• Cuttlefish adjust countershading to their body position

• e.g. Peppered Moth
• Peppered moths are polymorphic, existing in two forms - typica (light) and carbonaria (dark)

• England 1880's
• - Conversion to industrial economy
• - Burning soft coal
• - Killed lichens
• - Soot covered countryside

Decline in typica and increase in carbonaria

With decline in pollution, lichens have regrown (typica increased)

• Polluted area:
• - Moths on trunks eaten more than on limbs (for both morphs)
• - Typicas were eaten more than carbonaria

• Non-polluted:
• - Moths on trunks eaten more than on limbs in dark morphs, but little difference in light morph (trunk slightly more depredated)
• - Dark morph eaten more than light morph

• Computer models attempting to predict relative abundance of typica and carbonaria
• - Consistently underestimate abundance of carbonaria
• - More carbonaria than expected

• Departure of observed numbers from predictions of model due to moth behaviour
• - Moths don't rest in exposed positions
• - Rest under branches
• - Carbonaria has cryptic advantage

• Peppered moths
• Selects appropriate trees and patches within those to light
• Orients on trunk so that markings aligned with lines in bark
• Remain motionless

• e.g Northern water snake
• Newborn water snakes are cross-banded - easy to detect
• When disturbed, move forward rapidly - crypsis enhanced

• Use of urea as a chemosensory cloaking molecule by a bony fish (toadfish)
• Synchronized urea (expensive to produce) excretion at dawn and dusk

• Aposematism
• Pronouncement of vigilance

• Advertisement of dangerous or unpleasant attributes
• Advertised in terms of:
• i. visual cues
• ii. acoustic cues
• iii. chemical cues

• Warming colouration:
• e.g. skunks, poison dart frogs (block calcium channals), wasps
• Opposing colours

• Threat displays
• - hackle raising.arched back in cats
• - s-shaped neck in geese
• - baring of gums and teeth in dogs
• - Porcupine fish (puff off and spines)(block Na channals)
• - Frilled lizard (flaring neck flaps)

• hissing cat
• snake rattle
• beak clipping in great horned owls

• e.g. stink-pot turtle
• "The strong smell of the aptly named stink-pot turtle warns predators of its bad-tasting flesh, pugnacious dispositions and unhesitating bite" Tom Eisner

• Behaviours critical to effective aposematism
• Renders display and aposematic individuals more conspicuous
• Aposematic individuals are typically:
• Active during day - likely to be detected by visual predators
• Aggregative:
• - associate with other aposematic individuals
• - Emphasizes warning signal

• e.g. anuran amphibian tadpoles (Bufo bufo)
• - Black colour emphasized when grouped together (have a toxin)

Predators learn rapidly to avoid prey that have some distinctive aposematic display and are noxious in some way

• But,
• such benefits aren't restricted to members of one's own species

• Where multiple noxious species have evolved similar aposematic patterns
• e.g. bees and wasps
• e.g. Viceroy and Monarch

• e.g. ant-mimicking spiders
• Ants (6 legs, 3 body segments) Class Insecta: protected by sting, mandibles, chemicals

• Spiders class Arachnida (8 legs, 2 body segments): have venomous bite
• - Artifical looking head, extra pair of legs mimics antennae

• Members of a harmless species that have evolved morphology and/or behaviour mimicking a dangerous species
• e.g. King snakes and coral snakes
• e.g. bee flies

• Predators rely on remaining undetected
• Once detected, predator will often give up attack (bc prob. of capture is decreased on noticed)
• Pronouncement of vigilance displays indicte predator detected
• e.g. Stotting and tail flagging in deer

Predator inspection may serve as a pronouncement of vigilance deterring attack

• e.g. Fitzgibbon 1994 "The costs and benefits of predator inspection behaviour in Thomson's gazelles"
• --> comprehensive examination of costs and benefits of predator inspection by gazelles in Serengeti National Park

• Gazelles live in groups of 10 - 500 individuals
• Predators include lions, cheetahs, spotted hyenas and wild dogs
• Gazelles approach lions and cheetahs but not hyenas and wild dogs
• - Cheetahs and lions rely on surprise
• - Hyenas and wild dogs rely on stamina
• - Approaching the latter "invites" hunt

Results suggested that primary benefit of predator was deterrence of attack

• Risk of predation for inspecting lions and cheetahs low
• - Adults approach - 1/5000th chance of predations
• - Young approach - 1/400th chance of predation

• Cost of time lost from other activities minor
• - Spend 4% of time approaching predators

• Large cats respond to approaches by giving up hunt and moving further between rest periods and between hunting periods
• - Cause large cats to leave area sooner
• - Reduced mortality among gazelles

• A. False structures
• i. Permanently visible eyespots
• ii. False heads

B. Strike attractant lure

C. Autotomy

D. Feigning injury or death

• i. Permanently visible eyespots
• Typically found on non-vital area
• Misdirect predator's attack away from head
• Allow escape with non-fatal injury

• ii. False heads
• Predators often direct attack at head - incapacitates prey
• Some species have evolved false heads remote to actual head
• Effectiveness enhances by behaviour
• - turns instantly 180 degrees upon landing
• - Moves false anntennae
• i.e. Arawacus togarna

• e.g. California ground squirrels approach and tail flag at rattlesnakes
• - Resistant to rattlesnake venom
• - Deflects attack to non-vital structure

California ground squirrels discriminate between snakes (Gopher snake and rattlesnake) and tail flag accordingly (Aaron Rundus)

• e.g. Cephalopod pseudomorphs
• - Body-sized clumps of ink and mucous
• - Alternative inking strategy of octopods and cuttlefish
• Deflect
• obscure senses
• warns conspecifics of nearby danger

Predators often go after the peudomorph

• Reliquishing body part when attacked 
• e.g. lizards, salamanders, snakes and rodents known to autotomize tail

• Promotes escape
• - Animals breaks free
• - Predator distracted by tail thrashing
• - Thrashing increases handling time
• (tail thrashing can last up to 3 minutes)

• Sea cucumbers
• - Forcefully expel visceral organs through rupture when attacked
• Predators feeds on organs (part of respiratory tree)  as sea cucumber escapes
• - Also nasty (chemical) tasting

• Killdeer broken wing display
• Selectively directed toward predators and not other threats (e.g. cows)
• With cows, they sit on nest and call out warnings to cows

• Virginia opossum playing dead
• - Canids tend to release prey once dead
• - Often canids don't eat dead things
• - Opossums don't have evolved defenses against cars
• Effectiveness context dependent

• Hognose snake feigning death ritual
• - Writhe violently, roll over, defecate and protrude tongue

• visual
• auditory

• Startle predator at moment of attack
• May serve to deter attack or distract predator long enough to allow escape
• e.g. Moth having owl looking eyes

• Arctiid moths
• Produce loud clicks when disturbed
• May startle or serve as aposematic warning of chemical protection
• --> function addressed experimentally
• Bates and Fenton 1990

Trained big brown bats to fly to a platform for a mealworm reward

• Broadcast arctiid clicks at platform
• - Naive bats veered off
• - Ultimately habituated to clicks

• Mealworms injected with quinine sulfate
• - bats learned to associate protected mealworms with clicks and avoided them

--> More aposematism than startle

• e.g. Flying fish and tuna
• 2-winged fish propel themselves from water when tuna detected 
• - exit water quickly
• - fly short distance
• - tuna swim past
• Premium on getting out of water quickly
• Tuna swim in a straight line generally

• Not useful where dolphin fish prey on flying fish
• 4-winged fish propel themselves from water
• - exit water slowly
• - fly long distance
• - maneuver away from predator
• Premium on distance and maneuverability

California ground squirrels with rattlesnake

• Confront snakes with:
• - tail flagging
• - biting
• - paw swiping
• - kicking sand and dirt (defensive burying)

• Most species fight back to some degree
• Some have evolved specialized defences

• Some species have highly specialized weapons
• When disturbed, forcefully ejects chemical spray e.g. Bombardier beetle
• - abdomen tip revolves directing spray

• Spray composed of quinones & H2O2
• - Stored separately
• - When mixed with anzymes reaches boil

Spray is a hot irritant - can kill nverts

• Some species have specialized weapons e.g. horned toad
• When disturbed forcefully ejects blood from corners of eyes
• - Stored in infraorbital sinuses

• Stored blood contains a chemical irritant (also tastes bitter)
• - deters predators

Some species get others to do their fighting for them

• Dinoflagellates
• Preduce light when disturbed via deformation of cell membrane
• Proposed that bioluminescence serves to attract predators of the dinoflallate's grazers
• - signalling fish predators that prey are available
• The burglar alarm

• Dinoflagellates bioluminscence
• Reported that aposematism (chemicals in dinos don't affect predators) (Schantz 1971) and Startle (Esaias & Curl 1972) suggested as alternative hypotheses

Experimentally tested whether bioluminescence increased the mortality rate of copepods grazing on dinoflagellates

• METHODS
• Established two treatment populations of dinoflagellates in 20 8-L jars
• Experimental: cultured on normal photoperiod and could bioluminesce at time of trials
• Control: cultured on shifted photoperiod and could not bioluminesce at time of trials

• Added equal numbers of copepods to experimental and control cultures
• Added a 3-spine stickleback to each culture
• After 5.5 h quantified copepod mortality

• RESULTS
• More copepods depredated in experimentals
• Burglar alarm hypothesis supported

• Also evident in plant/herbivore/predator tri-trophic interactions
• - Plant produce chemicals that attract predatory mites when attacked by herbivorous mites
• Doesn't preclude secondary function of signals (e.g. startle, aposematism)
• Doesn't indicate that predator/prey interactions involve more than just consumption

--> predators select for substantial modifications of prey behaviour

• Have focused on antipredator behaviour of individuals
• Individual animals aggregate together to form groups
• --> Antipredator benefits of group living

A primary force in the evolution of animal sociality

• 1. Dilution of individual risk
• 2. Satiation of predator appetite
• 3. Confusion effects
• 4. Risk of physical injury to predator
• 5. Mobbing
• 6. Improved detection of predators

• Within a group, each individual has a reduced probability of being attacked by a predator
• - Simple product of numerical odds
• - Predator is likely to take someone else
• --> But not all individuals within a group experience equal risk

• Group members appear to coordinate defense, but each individual behaves selfishly
• - central individuals in group enjoy less risk

• Individuals on periphery have higher risk
• - More likely to encounter predator first
• - Recall "half-awake" to the risk of predations in mallards
• - Experience fewer other benefits of grouping (thermal regulation, info sharing)

Applies well to some species but not to others

• Where predators can enter group in 3 dimensions
• - Avian or aquatic predators
• - No advantage to central position

• Where dominants defend weaker individuals
• - Dominants choose peripheral locations
• --> is this altruism? ---- NO

• Behaviour that benefits the fitness of others at a fitness cost to one's self
• e.g. defense of females and young by dominant male baboons protects past reproductive investment and future productive potential

• Is not ALTRUISTIC
• - Males experience cost, but
• - receive offsetting benefit

• Predators can only eat a finite amount/unit time
• By living in a group, potential prey "swamp" predator appetites
• Ensures that some individuals survive
• Particularly true for production of vulnerable young in group-living species
• - Reproductive synchrony ensures survival

• Described initially for colonially nesting birds by Fraser Darling
• Refers to how visual and auditory displays of neighbours accerelate and synchronize the reproductive cycle of adults within the colony (cawing and flapping of wings)
• Results in synchrony of nesting and hence offspring production, satiating predators
• e.g. Human menstrual synchrony and suppression -> via pheromones (cooperative breeding, to offset polygyny).

• First described by Robert Miller 1922 for flocks o f small birds in the prescence of a hawk (bush tits)
• Predators may hesitate or become confused when confronted with several prey items simultaneously
• Miller found that hawks were less successful in attacks on groups than on single individuals

• Attacking a group may lead to injury via collision or trampling
• e.g. Zebras, wildebeest, birds

• Approaching and harassing enemies en masses
• Bank swallows mob:
• - terrestrial predator (weasels)
• - avian predators (blue jays)

• Cape ground squirrel males
• - actively mob snakes

• Even outside the context of integrated groups ind. cooperate to mob predators
• - red-winged blackbirds mob crows
• - crows mob owls and other birds of prey
• - even mixed sp. will work together (godwits and lapwings)

• 1. Direct deterrence
• A. Confusing predator
• B. Pronouncement of vigilance
• C. Risk of physical injury

• 2. Other benefits
• A. Alert others to predator's presence
• B. Teach offspring to recognize predators

• "Many eyes" hypothesis
• Many individuals, each with their own finite probability of detecting an approaching predator, increase the overall probability of a predator being detected

• Benefits:
• Increase prob. of avoidance or escape (w/ early detection)
• Facilitates coordinated defense
• Enhances overall foraging efficiency

Allows individuals to devote time to foraging while others vigilant for threat

• Can involve:
• - Sentinel system (e.g. Meerkat
• - Diffuse vigilance

• Examined influence of group size on foraging/vigilance trade-offs in black-tailed prairie dogs
• Artificially reduced group size by temporarily removal
• Individual vigilance increased as group size was decreased
• Increased vigilance decreased time devoted to foraging

• beyond the bounds of a single species
• Passerine birds form mixed species flocks
• - each individuals benefits from the vigilance of others

the detecting individual must alert others to the presence of the predator

--> Members of most group-living species respond to the presence of a predator with the production of an alarm signal

Displays or stimuli produced in the presence of a potentially threatening stimulus

• Occur in many different sensory modalities
• - Selected by organism's environment

• Birds and mammals --> vocal signals
• Fish, amphibians, insects and plants --> chemical signals

• e.g. damage to sagebush by herbivores
• - causes release of methyl jasmonate
• - results in production of polyphenolic compounds in neighbouring tobacco

• perform a "jump-yip" display
• Combines visual and acoustic elements
• Not an alarm call per se
• Contagious
• Originally thought to be alarm or "all clear" signal
• Provides colony members with info on vigilance of neighbours

The assess how vigilant their neighbours are, if really vigilant can devote more time to foraging

• 1. Pronouncement of vigilance
• 2. Manipulate conspecifics
• 3. Warn others

• By issuing alarm, signaler informs predator that it has been detected 
• "Pursuit-deterrent signals"

• e.g. Wesern swamphen Hasson 1991
• - reduce cost to signaler
• - benefit predator by providing info regarding potential  success

• Charnov and Krebs 1975
• - Signal may cause others to move
• --> movers more conspicuous to predators
• - decreases risk to signaler

• Doesn't seem to occur in context proposed
• --> selection favours selective receivers (who aren't duped)

• - Manipulative signals do occur
• e.g. chimps - false alarms to get access to food and mates
• e.g. great tits
• e.g. femme fatales - aggressive mimicry
• e.g. slave-making ants: produce propaganda chemical signal to make the host worker flee nest

Enjoys broadest support across species

• Ground squirrels produce vocal alarm signals
• Call recipients respond by becoming vigilant and/or escaping to burrows
• But signalers experience a cost:
• - Sherman (1977) found for Belding's facing terrestrial predators
• --> callers - 8% captured
• --> silent - 4% captured

• "Schreckstoff" - shock matter
• The name given to chemical alarm substance released from damaged skin cells of fish

• Released when a fish is consumed by a predator
• Causes others to respond immediately with rapid darting, followed by hiding and reduced activity
• Known for minnows, darters, and gobies
• Similar system for frog and toad tadpoles

Alarm signaler pays with its life

• True altruism
• Costs of individual's behaviour exceed any benefits of that behaviour
• --> would be selected out by definition

Such altruists would leave fewer copies of their genes than others

Individual's behaviour appears costly but costs are offset by others benefits that enhance fitness

• e.g. Dominant baboons defending others
• - Costs are offset by protection of young and mates
• - Similar argument can be made for alarm signaling

Selection favouring behaviour or traits that promote the survival of the group an animal live in

Wynne-Edward 1962 "Animal dispersion in relation to social behaviour"

Disadvantageous consequences for individual outweighed by benefits to group

• Alarm calling
• Self-sacrificing defence or rescue
• Reproductive restraint (e.g. sterile caste of ants)

• BUT,
• it was ultimately argued that the group selection argument is fatally flawed

unable to keep pace with selection operating on individuals

• A disadvantageous trait cannot become characteristic of all individuals in a population
• Individuals avoiding disproportionate advantage
• Cheaters would readily replace altruist in the population
• e.g. Lemmings "group suicide" watched "white-wilderness"

• Both mathematical models and empirical studies do suggest that group selection can contribute to the evolution of behavioural traits
• - But only under certain highly restrictive circumstances, where:
• Group sizes are very small
• Migration between groups is low
• Extinction rate of groups is high

• "..he who was ready to sacrifice his life, as many a savage has been, rather than betray his comrades, would often leave no offspring to inherit his noble nature"
• "... a tribe including many members who... were always ready to give aid to each other and sacrifice themselves for the common good, would be victorious over most other tribes; and this would be natural selection

• group selection concept
• Wilson (stuck to his guns/convictions) 1980
• "The natural selection of populations and communities"

But group selection cannot offer a general explanation altruism

• Who else has like copies of your gene?
• Parents, uncles, aunts, grandparents, nieces, nephews, grandchildren
• --> your relatives

Fitness benefits can accrued by helping individuals who share like copies of your genes to reproduce

Inclusive fitness theory

= direct and indirect fitness

Direct fitness: like genes propagated via the production of one's own offspring

Indirect fitness: like genes propagated through effects on the reproductive effort of related individuals

• Selection will favour individuals that endure costs to their direct fitness if those costs are more than compensated for by benefits accruing via indirect fitness
• e.g. costs of alarm signaling

Recognized the need to distinguish selection acting to promote  direct fitness benefits fom selection promoting indirect fitness benefits

--> coined term "kin selection"

Selection for behaviour or traits that enhance the fitness of related individuals

• "Animal are expected to behave in a manner that maximizes their inclusive fitness"
• Maynard Smith 1964

equal in their ability to advance your indirect fitness

• Closer kin share more genes by common descent
• - Investment in closer relative can provide greater fitness payoff

Extent of relatedness expressed as the coefficient of relatedness (r)

The proportion of alleles an individual shares with another by common descent

• Identical twin = 1.0
• Mother/father = 0.5
• Full sib = 0.5
• half sib = 0.25
• grndparent, grandchild = 0.25
• Aunt/uncle/niece/nephew = 0.25
• first cousin = 0.125

• Calculating r
• r = sum(0.5)^L

L = # of links to a common ancestor

Predicts when foregoing your own reproduction for that of another would be advantageous due to kin selection

C < Br

• C = cost to actor in terms of offspring produced
• B = benefit to actor in terms of offspring produced by relative
• r coefficient of relatedness between actor and recipient

• e.g. If sister, need to produce 2 offspring to make up for the loss of one of my own offspring
• If 1st cousin - need 8 offspring

• How should an animal partition aid among related individuals?
• - Distributed among relatives in proportion to r?
• e.g. if sister (r = 0.05) and cousin (r = 0.125) are available, sister should receive 4x the aid that the cousin receives

But if your sister can use the help, why give any to your cousin?

• Altmann 1979 "Altruistic behaviour the fallacy of kin deployment"
• Partitioning aid among all available relatives doesn't maximize indirect fitness benefits
• Animals are expected to focus any aid offered on their closest relative
• But factors beyond r influence the expression of nepotism

Favoritism toward kin

• 1. Probability that recipient will use aid to produce offspring
• 2. Certainty of relatednss
• 3. Potential competition

• Don't help infertile individuals
• - No aid for reproductively senescent
• - No aid for those who are "infirm"
• Be aware of diminishing returns 
• Invest in members of the rare sex (limited factor)

• Help female rather male kin
• --> avuncular control" (Mother's brother vs. paternal uncle)
• Mother's brother has more more certainty of like kin

• Help sister rather than mother
• Don't assist individuals who will compete with your own young

• black-tailed prairie dogs
• Towns structured as female kin clusters
• - neighbours are maternal kin

• Females commit infanticide
• - selectively kill offspring of close king 
• - because kin are competitors

• 1. Nepotistic alarm calling
• 2. Kin-biased alloparental care
• 3. kin-differential cannibalism
• 4. Kin-biased affiliation
• 5. Sterile castes in eusocial insects
• 6. Ubiquity of kin recognition

• Sherman 1985
• Examined responses of Belding's ground squirrels to avian and terrestrial predator attacks
• Females show natal philopatry (female stay in natal area): results in female kin clusters
• Long term study with known genealogies
• Squirrels give qualitatively different calls to avian and terrestrial predators

• Alarm calls to aerial predators: call in proportion to abundance
• Alarm calls to terrestrial predators: adult and yearling females call more than expected by population

• Females are more likely to call than males
• - Consistent with kinship theory given female philpatry

• Adult and yearling females are more likely to call than juveniles
• - results could be explained by maternal investment as readily as kin selection
• - They r reproductive

• Reproductive females without close kin call more often than non-reproductive females without close kin
• - maternal investment does play a role

• Reproductive females with descendant kin more likely to call than reproductives without descendants
• - mothers call to protect young

• Reproductives with mom or collateral kin are more likely to call than reproductives without such kin (& resident > non-resident)
• - kin selection also contributes to calling (nepotism)

Investment in young by individuals who are not the biological parents of those individuals

• Primates --> aunting
• Birds --> helpers

• Aunting:
• Individuals selectively care for related young
• More distantly related young handled more roughly than close relatives

• Helping:
• Typically sexually-immature birds that remain philopatric in natal area
• Help parents raise non-clutchmate siblings

--> explained by kin selection

• Spadefoot toads
• Tadpoles are polyphenic: normal/herbivorous and cannibal/carnivorous morphs

Pfennig Reeve, Sherman 1993

• Contrasted behaviour of normal and cannibal morph individuals
• - cannibals preferentially associated with non-siblings
• - cannibals were more likely to spit out siblings than non-siblings

--> explained by kin selection

• Have seen multiple examples already:
• Natal philopatry and female kin clustering in ground squirrels
• Philopatry of avian helpers
• Aggregation of sibling common toad tadpoles (and other aposematic young)
• Colony membership in eusocial insects
• --> promotes kin selection

• Truly/highly social insects
• Ants/bees/wasps and termites
• Defined by Wilson 1971 as animals having:

• Cooperative care of young
• Reproductive division of labour
• --> with more or less sterile individuals labouring on behalf of reproductives
• Overlap of ≥2 generations
• --> young help mother in subsequent reproduction

Eusociality not limited to insects e.g. naked mole rats (Sherman)

• Perceived as a major dilemma by Darwin
• Presented a "special problem" for evolution via natural selection

• Product of the Haplodiploid mechanism of sex determination
• Males: haploid (n); arise from unfertilized eggs
• Females: diploid (2n); from fertilized eggs of queen; develop into workers or queens

• Workers - all females
• Lack spermatheca
• Have three reproductive options:

• Produce own haploid males
• --> r = 0.5

• Help mother produce sisters
• --> r= 0.75

• Help mother produce brothers
• --> r = 0.25

• inseminating queen is haploid - produces sperm mitotically
• - all sperm have identical alleles

• All female progeny are diploid
• - half of each female is from male sperm
• --> thus r = 0.5 from male side
• - half of each female is from female egg produced meiotically
• --> thus on average, 50% commonality for 50% of individuals
• --> r = 0.25 from female side

r full sister = 0.5 + 0.25 = 0.75

• From queen's perspective:
• sons produced from unfertilized eggs
• - eggs produced meiotically
• - r = 0.5

• From worker's perspective:
• sons produced from unfertilized eggs
• - share nothing of paternal side that accounts for 50% of worker
• - share on average 50% of 50% of selves that is contributed via queen's egg
• - r = 0.25

• Queen - equally related to sons and daughters (r son = 0.5, r daughter = 0.5)
• - 1:1 investment in male:female reproductives

• Workers- more closely related to sister than brothers (r sister = 0.75, brother = 0.25)
• - 3:1 investment in females:male reproductives

--> whose interest win out?

• Intuitively may think queen will prevail
• - she determines whether eggs are fertilized
• - decides rate of production males and females

• Workers are more likely to win out
• - responsible for feeding larvae and general tending of all developing brood
• - can eat brood produced by queen

--> sex ratio data provide convenient test of kin selection theory

• If worker's interests prevail
• - expect 3:1 ratio of investment in females: males

• Workers have r = 0.75 to sisters produced by queen
• Workers have r= 0.25 to brothers produced by queen

Trivers and Hare 1976

Predicted that if eusociality in ants, bees, and wasps evolved via kin selection, investment in female reproductives should be 3x that made in reproductive males

• Examined sex ratio of reproductives in colonies of 21 species of ants
• - found ratios did not depart significantly from 3:1 (female:male) in those species

• Did report some species departing from 3:1 ratio
• 1:1 ratio of investment in colonies of slave-making ants

• Enslaved workers unrelated to brood
• No fitness increase by altering investment
• Optimal ratio for queen prevails
• -->consistent with kin selection theory

• Animals must discriminate kin from non-kin
• - Given potential fitness benefits associated with kin selection

Kin recognition is commonly expressed by animals

• Allows beneficent behaviour to be directed toward kin
• Two books on kin recognition:
• - Fletcher and Michener (19870
• - Hepper (1991)

Kin recognition has been documented in virtually all animal taxa

• Kaitz 1987 - mother/offspring recognition in humans
• Mother given no direct contact with young
• Presented t-shirts worn by own infant or another
• Identify own by odour alone with 85% accuracy

• Margo Wilson and Martin Daly
• Examined 512 cases of homicide committed in Detroit, MI in 1972

Only 6% of murders involved blood relatives

• 1. Spatial location
• 2. Familiarity
• 3. Phenotype matching
• 4. Recognition alleles

• Relies on spatial segregation of kin
• Relatives predictably found in certain area
• All individuals found in that area treated as kin

• e.g.bank swallows
• Parents learn location of their nest hole within colony
• Feed any chicks found there (treat them as kin)
• 2 weeks post-hatch, young make excursions and parents begin to reject alien young
• --> another mechanism comes into play

• Learning relatives via social experience with those individuals
• Relies on kin being reliably associated in space and time

• e.g. where young are altricial
• differential association occurs between own and alien young, allowing:
• --> parent/offspring recognition
• --> sibling recognition

Cross-fostering paradigm

After cross-fostering, presents four possible combinations of rearing x relatedness

• Natural
• Siblings reared together (SRT)
• Non-siblings reared apart (NSRA)

• Experimental
• Siblings rearer apart (SRA)
• Non-siblings rearedtogether (NSRT)

Allow test of both sufficiency and necessity of familiarity to recognition

If NSRT = SRT then familiarity is sufficient to allow individuals to be treated as siblings

If SRA ≠ SRT then familiarity is necessary to allow individuals to be treated as siblings

• Holmes 1984
• Cross-fostered young between litters immediately after birth
• Quantified exploratory contacts for all 4 possible dyad types in a neutral arena
• SRT = NSRT (low exploratory contact) < NSRA = SRA (high exporatory contact)

--> Familiarity is both sufficient and necessary to sibling recognition in 13 lined ground squirrels

• 1. Susceptible to errors of false inclusion
• - consider individual as kin who isn't 
• - occurs when individuals from one family inadvertently associate with individuals from another family

• 2. Prone to errors of false omission
• - exclusion of actual king
• - occurs where individuals aren't familiar with certain relatives

--> More reliable mechanisms exist

Holmes and Sherman 1982

• Cross-fostered immediately after birth
• tested dyads in neutral arena as yearlings
• Quantified aggression
• SRT=NSRT=SRA < NSRA

--> Familiarity sufficient, but not necessary for sibling recognition

a more refined recognition mechanism must exist

• Possibilities include:
• 3. Phenotype matching
• 4. Recognition alleles

• Proposed originally by Alexander and Greenberg
• Invoked by Sherman and Holmes to explain recognition of siblings in the absence of rearing association
• Individuals recognize kin by comparing (matching) the phenotype of each individual they encounter to a template of what phenotype constitutes kin

Of what constitutes kin is learned from reliable kin

• e.g. Mother is certain to be a relative
• Acts as referent
• Labels emanate from referent and allow formation of template of what phenotypic attributes constitute kin
• Subsequently encountered individuals compared to template to assess kinship

Buckle and Greenberg 1991

• Conducted research on sweat bees
• Sweat bees post nest entrance guards that control admission to hive
• Quantified admission relative to relatedness

• RESULTS
• Acceptance directly correlated with relatedness between guard and intruder

• Phenotype matching allows for recognition of inds./kin you've never met before
• removes error in false inclusion and exclusion

YOURSELF

The armpit affect

First purported evidence in 2000

Hauber, Sherman and Paprika 2000

Mateo and Johnston 2000

• Socially parasitic birds/ brown headed cowbirds
• - hatch in host species nest
• - limits referent to self

• Manipulated phenotype of hatchlings by making primary feathers of some black
• Tested these and ontrols for association preference with blackened and non-blackened models

• RESULTS
• Individuals showed preferential association with individuals that bore colours the same as those they had as hatchlings
• Conclude that early experience with self is the only way these results could come about

• Fostered young golden hamsters into another litter 3-12 h after birth
• Individuals reared with foster family to weaning
• Tested in arena as SRT, SRA, NSRA, and NSRT 
• Found SRA recognized each other as siblings
• Conclude this based on self-referent matching

• Hare et al. 2003
• Mateo and Johnston study not definitive since didn't control for exposure in utero and immediately post-partum
• - allowed differential familiarization with biological siblings

• Hauber et al. study did not definitive due to familiarization in testing situation
• - Preference for like-coloured individuals only became apparent in comparing final 3 trials to first 3 trials in a series of 6 trials of each subject
• - again, confound of differential familiarization
• - First 3 trials had no difference between individuals

neither considered alternative mechanisms

• Proposed originally by Hamilton (1964)
• Ability to recognize kin is inherited rather than learned

• An allelic system promoting kin recognition would have to have 3 simultaneous effects
• 1. Must produce some recognizable trait - a label - in all kin
• 2. Must produce the sensory apparatus needed to perceive the label in others
• 3. Must predispose bearer to show biased behaviour to others with the label

Mechanisms referred to as the "green beard" effect by Dawkins

• All bearers of allele have green beard
• Recognize same green beard in other
• Bearers show favouritism to other green beards

• Existence of recognition alleles is difficult to document
• - cannot prevent developing individual from having experience with itself
• --> can never negate possibility of self-referent matching in normal individual

• Recognition in some species is directly correlated with alleles of the genome
• - consistent with existence of recognition alleles

Grosberg and Quinn 1986 with colonial tunicates

• larvae aggregate with kin prior to metamorphosis to adulthood
• Recognition correlated with alleles of the histocompatibility locus
• - determines tissue compatibility

Yamazaki et al 1980 with house mice

• Alleles of H-2 locus of the major histocompatibility complex (MHC) affect mate choice in mice
• - individuals prefer mates with different MHC alleles
• MHC alleles affect odour production
• Mate choice based upon odour

Krieger and Ross 2002 with fire ants

Colonies can be monogynous (1 queen) or polygynous (> 1 queen) 

• State dependent upon allelic constitution of Gp-9 locus
• - produces protein responsible for odour detection

• Nests of BB ants are monogynous, Bb colonies are polygynous
• bb is lethal homozygous recessive
• BB workers kill all but one queen
• (have protein allowing queen recognition)

slime mold/ social amoeba

Queller et al. 2003. "Single-gene Greenbeard effects in the social amoeba Dictyostelium discoideum"

• Studied amoebic slime mold
• Normally exists in unicellular amoebic state in soil
• When soil bacteria (food) exhausted, individuals stream into aggregation of thousands of cells
• Within aggregation, ca. 20% of cells "altruistically" die to form a rigid stalk supporting other cells which differentiate into a cluster of spores

• Support stalk necessary to raise spore-producing body above soil surface
• Erection of sporophyte allows dispersal of spored to new food patch

• Aggregation aren't limited to members of a single clone
• Both in the lab and field, cells from different clones readily form chimeric fruiting bodies
• Aggregation is dependent upon a single gene locus called "csA" (contact site A)
• csA codes for a cell adhsion protein (gp 80) anchored in the cel membrane
• Most distal domain of gp80 shows homophilic binding to same domain in neighbouring cells

• Queller et al. used gp80 "knockout" mutants which lacked functional gp80 protein
• Found when plated along wild-type cells on soilplates, vast majority (82%) of spores were wild type
• Homophilic binding of gp80 domains coded by csA in wild type allowed better adhesion in aggregation streams
• Knockout cells with inferior adhesion left behind (and thus don't become spores)
• Wild-type cells benefit disproportionately over knockout cells

alleles of a single locus - csA - simultaneously exert 3 effects

• 1. Produce a label in bearers of the csA allele - gp80 homophilic domain
• 2. Ensure recognition of the allele in others - homophilic attraction
• 3. Ensure favouritism toward other "green beards" - preferential binding with other csA individuals

• Not necessarily
• - in slime mold, promote aggregation with all other csA ind. 
• - such individuals can be from different clones and hence not close relatives

• Greenbeards alleles may be "outlaws"
• - promote own propagation at the expense of other alleles of genome

Doesn't preclude (make impossible/prevent from happening) selective advantage where benefit accrues and diversity within locus is correlated with kinship

But limitations exist, and certain caveats must be expressed

I. Problems with haplodiploid explanation for the sterility of workers and eusociality in insects

II. Alternative mechanisms can account for apparent altruism

Wilson shifts his position on altruism in nature

a) Females mate multiple, diluting coefficient of relatedness among nestmates

b) Multiple problems exist with Trivers and Hare's sex ratio data

• Had explained worker sterility by high coefficient of relatedness between sisters
• but, r = 0.75 only when female is mated by a single male and same male sires all young
• Multiple mating is common

• e.g. honey bees queens mate with an average of 17 males
• - sperm mixes within spermatheca
• - r among females drops below 0.5

Relatedness doesn't effect honey bee brood production or cooperation influencing temperature regulation or honey production

• e.g. Underwood et al. 2004
• - Compared productivity and efficiency of control hives to matched hives with diluted relatedness
• Found no effect of relatedness on any variable

• Raised in critique by Alexander and Sherman
• i) analyses of Trivers and Hare flawed: many spp. departed from 3:1 ratio
• ii) workers can produce their own sons: expected investment with monogamy closer to 3:2 (sisters:sons)
• iii) observed female bias in investment can be explained by alternative mechanism: local mate competition

• Where mating opportunities are limited
• And one or a few sons could fertilize all available females
• The production of additional sons is unwarrented
• - additional males compete with existing sons for mating opportunities
• Selection favours female-biased broods

Mating data for the ant Myrmica schenki are consistent with local mate competition

Experimental data for the primitively eusocial bee, Augochlorella striata, support the kin selection hypothesis

• Mueller 1991
• Soil nesting sweat bees
• Examined brood sex ratio under two conditions
• - eusocial: original queen
• - Parasocial: replacement queen, diluting relatedness

• If local mate competition causes female bias
• --> both eusocial and parasocial colonies should have female-biased broods

• If kin selection accounts for female bias
• --> eusocial colonies are expected to have a more female-biased brood

• RESULTS
• Eusocial colonies have a more female-biased brood sex ratio than parasocial colonies

• --> Workers facultatively adjust sex ratio of brood to produce a female bias whena pronounced relatedness asymmetry exists
• --> Kin selection explains female-biased sex ratios in A. striata.

Kin selection isn't the only explanation for apparent altruism

• Behaviour that appears to impose cost on actor may also result from:
• a) individual selection
• b) reciprocal altruism
• c) byproduct mutualism

Consider ground squirrel alarm calling

• Calling in response to terrestrial predators a product of kin selection
• Calling to avian predators is not kin-biased, and if costly:
• --> could benefit signaler via enhanced social status (Zahavi) e.g. Wilson's roosters
• --> Cost may be mitigated by manipulation of others (Charnov and Krebs)

e.g. Chickens. Roosters that call more (in presence of predators) get the girl

• but successful manipulation is unlikely to be evolutionarily stable
• --> if those who are successfully manipulated are killed or even experience diminished fitness
• - their genes are selected out of the population
• - those who aren't "suckers" enjoy higher relative fitness

--> Eventually, there are no inds. left to manipulate

• Advanced initially by Trivers 1971
• - Selection will favour actors that incur a cost in assisting others
• - if the recipient returns the favour,
• - so that the actor experiences a net fitness gain
• Reciprocity offsets initial cost to actor

Unlike kin selection, benefits of RA can accrue among non-relatives

• the behaviour of the recipient
• Cooperate --> repay actor
• Defect -->  don't repay actor

• Payoff varies according to the expression of alternative strategies
• Evolution of reciprocal altruism can be explained via game theory
• --> The Prisoner's dilemma

• Name of the game from hypothetical scenario
• Two suspects who have committed a crime are arrested and isolated for interrogation
• Each offered deal of light sentence if they "squeal" on the other
• Each prisoner has 2 choices with respect to their behaviour relative to their partner

• Defect: "rat out" partner providing evidence that partner committed crime
• Cooperate: dent partner's involvement

Possible outcomes of Prisoner's Dilemma

One defects and other doesn't: the cooperating partner takes the bulk of the rap and gets the longest jail sentence. The defector gets off easy on the deal

Both defect: both go to jail, but split responsibility so each has shorter sentence than one above

Both cooperate: both go to jail, but split responsibility, and less evidence than mutual defection, so shortest sentence other than for sole defector

• 4 categories and payoffs
• Reward for mutual cooperation (3)
• Sucker's payoff (0)

• Temptation to defect (5)
• Punishment for mutual defection (1)

• On any one interaction (i.e. where criminals are caught for crime), the best strategy is to defect (since payoff always higher than cooperation)
• But if the same individuals have repeated encounters, inds do worse by mutual defection than by mutual cooperation

--> Hence the dilemma: to defect or cooperate?

Fitness consequences of adopting different strategies over a lifetime can be determined via computer simulations

• Of all possible strategies
• - all cooperations
• - all defections
• - various ratios of both

The strategy that consistently provides the highest lifetime fitness payoff is:

--> "Tit for tat"

• The actor begins by behaving cooperatively, and then in all subsequent encounters, matches its interactant's previous action
• Actor           C C C D D C
• Interactant  C C D D C

• Strategy thus involves:
• Retaliation: follow defection with defection
• Forgiveness: forget past defections if partner switches to cooperation

• Is an evolutionarily stable strategy
• - once established in the population, it cannot be invaded by other strategies because it cannot be bettered

• But there is one strategy that can beat tit for tat in computer simulations
• - "cheat if you can get away with it"
• - obtain payoff of own defection without retaliation of partner
• - but assumes partner can't detect defection or can't retaliate

• Selection will favour retaliation to avoid receiving the sucker's payoff
• - better to take the punishment for mutual defection

• Selection will also favour inds who can detect defectors
• - thereby avoiding defectors as social partners and retaliating against them