Animal Behaviour

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Animal Behaviour
2015-12-07 02:29:25

U of M midterm
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  1. L6 Methods for resolving genetic similarity
    • Starch-gel electrophoresis of protein alloenzymes
    • DNA fingerprinting
    • microsatellite analysis
  2. Genetic similarity detection - Sherman and Holmes
    • Belding's GS
    • Full sibs more cohesive than half sibs

    Kinship important to sociality
  3. Genetic manipulation - circadian rhythms and fruit flies
    • Daily patterns of certain activities
    • Biological clock keeps on 24h cycle. Entrained by extrinsic stimuli

    Patterns of Emergence - Konopka and Benzer
  4. Genetic manipulation - social behaviour in voles 
    Young et al.
    Vole characteristics
    • Prairie: Affiliative, monogamous, bi parental care
    • montane: solitary, promiscuous, little parental care
  5. Vole neuroanatomy - young at el.
    • Comparative neuroanatomical study revealed difference in concentration and distribution of Arginine Vasopressin (AVP) receptors in vole brain
    • Prairie: More AVP receptors and concentrated in diagonal band
    • Montane: Fewer AVP receptors, concentrated in lateral septum
  6. Influence on AVP on affiliative behaviour
    Adminstration of AVP increases affiliative behaviour in prairie, but not in montane voles

    AVP involved in the PROXIMATE control of affiliative behaviour
  7. What does Young et al. study demonstrates?
    • Genes can control even complex behaviour
    • The comparative method is useful for generating hypotheses at both the ultimate and proximate level
  8. Is everything we observe adaptive?
  9. Non-adaptive or maladaptive traits are often expressed due to:
    • Domestication
    • Context-dependence
    • Developmental anomaly
    • Disease/pathology
    • Parasitism (induce change in behaviour)
  10. Non-adaptive or maladaptive traits are often expressed due to:
    • Selectively neutral behaviour aren't selected
    • Mutation and recombination produce new behaviours
    • Pleiotropic gene effects occur
    • Linkage occur between loci
    • Evoluntionary time lags occur
  11. Natural selection itself may render yesterday's adaptations moot
    • Selection for traits in one species may change the conditions for other species
    • e.g. predator-prey interactions
    • Evoluntionary arms race
  12. Red Queen Hypothesis (Van Valen)
    Animals must constantly evolve to maintain the same state of adaptation relative to their environment
  13. Coevolution
    • Reciprocal adaptations in interacting species due to natural selection imposed by each specie on the other
    • Predator-prey
    • Symbioses
    • Host-parasite
    • Mutualists
    • Commensalists
  14. Behaviour isn't always adaptive
    • Central principle provides framework for erecting testable hypothesese
    • stimulates research
    • Enhances understanding of behaviour
    • e.g. Tinbergen and Black headed gulls
    • Delay in removal of egg shells appear maladaptive. Tinbergen maintained delay must be adaptive
  15. Why don't the black gulls adopt other "better" behaviours
    • Behaviour don't appear because they are adaptive
    • Mutations must occur which promotes expresion
    • Natural selection acts on expressed behaviour
  16. Why is cannibalism adaptive?
    Infanticide is common among animals.
    3 major explanatory hypotheses?
    • Resource exploitative hyp.
    • Resource competition hyp.
    • Reproductive opportunities hyp.
  17. Understanding the adaptive basis of behaviour - 3 empirical approaches
    • Observational
    • Comparative
    • Experimental
  18. Observational Approach
    • Animal observed in their natural setting to gain insight into the adaptive basis
    • e.g. Tinbergen's Black headed gulls
  19. Comparative Approach
    • Members of the same species or closely-related species studied in different environmental conditions
    • - Different environments impose different selection pressures
    • - Differences in behaviour can be attributed to natural selection adapting organisms to their environment
  20. Comparative approach - Social behaviour of Marmot
    Adaptive basis of coloniality in marmots

    • Woodchuck at low 
    • Yellow-bellied at medium
    • Olympic at high
  21. Barash's Interpretation
    • Growing season length is critical because marmots must attain sufficient mass to get through winter hibernation
    • With increasing elevation and decreasing growing season length
    • - Aggression detrimental because it interrupts foraging
    • - Tolerance toward young and retention in natal area advantageous
    • -> Reduced food availability selects for increasing sociality
  22. Problem with comparative approach
    • Based on correlation
    • - correlation ≠causation
    • - another variable may underlie increased social behaviour 
    • e.g. predation pressure increases as elevation increases
    • coloniality and sociality impart antipredator benefits
  23. Experimental Approach
    • experimenter proposes a hypothesis for the adaptive function of a behaviour
    • manipulate some aspect of the animal or its environment to test that hypothesis
    • - Nature of groups
    • - Extent of manipulations
    • - Other factors to control
  24. Beyond empirical approaches, there is also 3 theoretical approaches to understanding the adaptive basis of behaviour
    • Assumption of Adaptiveness
    • Optimality Theory
    • Game Theory
  25. Theorectical approaches to adaptation -
    Assumption of Adaptiveness
    • From Central Principle
    • Focuses explicitly on benefits
  26. L9 Optimality Theory
    • Accounts for both costs and benefits of trait
    • Trait evolved to represent an optimal balance between benefits and costs

    • Natural selection weighs costs and benefits of each alternative
    • Common currency -> FITNESS

    • Behaviour that results is that which maximizes the difference between costs and benefits
    • -> Provides highest NET fitness pay off
  27. Using optimality models
    • Must be able to measure fitness
    • But lifetime measure impractical
    • Therefore assume: Optimality long term is reflected in optimality short term
    • e.g. seasonal reproductive success
    • time/energy budgets
  28. e.g. Optimality and Territoriality
    Define Territory
    • a fixed area defended against rivals for a period of time
    • an area of exclusive use
    • related to resources
    • may vary over time
  29. Optimality Theory
    Animal should hold a territory where benefits exceed costs
    Benefits of holding a territory
    • Guaranteed access to resources
    • Enhanced acquisition of mates
    • Reduced transmission of disease
    • Reduced predation (protection of young and mates)
  30. Optimality Theory
    Costs of holding a territory
    • Increased energy/time expenditure
    • Enhanced risk of injury or death (increased competition with conspecifics, attraction of predators via displays)
    • Lost opportunity to exploit shifting resources
  31. Resource attributes influence economics of territoriality. 3#
    • 1. Resource abundance
    • 2. Resource distribution (space and time)
    • 3. Degree of competition for resources
  32. Resource abundance
    e.g. and an "in general"
    • Galapagos marine iguana on Hood island - Nest sites in short supply
    • Decreasing resource abundance increases the likelihood of territoriality
  33. Resource distribution
    e.g. and an "in general"
    • Everglades Pygmy Sunfish - males defend territories near clumps of prey, aren't territorial when prey are evenly disperses
    • In general: Incidence of territoriality increases with clumping of resources
  34. Competition for Resources
    e.g. and an "in general"
    • Male fruit flies defend small areas of food
    • Increasing competition increases defence costs, decreasing incidence of territoriality
  35. Dimished benefits/increased costs may preclude formation of territory
    • Territories are dynamic
    • Animals can maximize net gain by optimizing location, size, or time over which they hold a territory
  36. e.g. for optimization of territory size
    • Rufous hummingbird - Carpenter
    • Defend territories around patches of flowers at stopover site
    • Optimal size that allowed the greatest weight gain
  37. What is the true value of optimality models?
    Suggesting hypotheses that can be tested experimentally
  38. Frequency-independent optimality models
    Where optima are independent of frequency of behaviour seen in other individuals
  39. Frequency-dependent optimality model - Maynard-Smith
    Optimality models is which the optimum strategy is contingent on the frequency of behaviour in others

    -> Part of Game Theory
  40. Game Theory
    • Individuals play certain strategies against each other
    • Winning is equated with enhanced fitness
    • Theoretical approach #3 to adaptation
    • Behaviour can be treated as a strategy to maximize reproductive success (doesn't imply conscious selection of strategy)
  41. Where multiple strategies exist (alternative strategies)
    • e.g. Crickets Sneaky fuckers and callers
    • Success of each strategy depends on what others are doing (payoffs are frequency dependent)
    • Ultimately reach equilibrium
  42. Evoluntionarily Stable Strategy (ESS)
    A strategy or set of strategies that once adapted by a critical proportion of the population cannot be replaced by other strategies
  43. Single strategy - Pure ESS
    • Single behavioural strategy manifested by all normal members of a population
    • Resistant to invasion bc it cannot be bettered by existing alternative strategies
  44. Two types of Mixed ESS
    • 1. Each ind. consistently plays one of the possible strategies so that the relative proportion of pure strategies in the population remain stable
    • 2. Each ind. varies its strategy, playing each with a certain frequency
  45. Mixed ESS
    A set of strategies that exist in an evoluntionarily stable ratio
  46. Nash equilibrium
    Balance point occurs at ratio where the strategies impart equivalent reproductive success
  47. Game Theory
    • Attempts to understand the expression of alternative strategies through the use of mathematical models
    • Simplest of these involve construction of a "pay-off matrix"
    • e.g. game theory model for understanding the adaptive basis of aggression among conspecifics (Hawk and Dove)
  48. Pay-off matrix
    Formally states fitness payoffs to individuals playing all possible strategies
  49. Hawks versus Doves
    Simple game involving two strategies 
    Aggressive; continue to fight until seriously injured or opponent retreats
  50. Doves
    Passive; show aggressive displays, but always retreat rather than fight
  51. Predictions of Hawk vs. Dove model?
    • 1. Populations will be composed of both hawks and doves
    • 2. With increased cost of injury, doves will enjoy higher relative fitness
    • 3. Intensity of fighting will increase with increasing resource value
  52. Populations will be composed of both hawks and doves
    • Pure dove pop. susceptible to invasion by hawks
    • Eventually forming a mixed ESS of Hawk and dove
  53. With increased cost of injury, doves will enjoy higher relative fitness
    • Average payoff of hawk-hawk encounters would be low
    • Higer proportion of doves at equilibrium
    • Predict that in well armed species, hawk strategy would be rare
  54. Intensity of fighting will increase with increasing resource value
    • Since overall pay-off increases
    • Hawk may be become pure ESS if pay-off is large and resource is limited (elephant seals)
  55. L10 Altruism and Apparent altruism
    • Behaviour that benefits others at a cost to the actor
    • True altruism would be selected out
    • Expressed by elderly: reproductive senescence negate costs
  56. Game theory can be refined via incorporation of asymmetries among interactants
    • 1. Ability to defend a resource (resource holding potential)
    • 2. Value of the resource
    • 3. Uncorrelated/arbitrary asymmetries
  57. RHP and Conditional Strategy
    • Ind. are rarely equal opponents
    • Size most consistent predictor of RHP 
    • Selection favours Conditional strategy - strategy is dependent upon opponent
    • e.g. Funnel-web spiders and big horn sheep.
  58. Assessors
    that show conditional strategies readily invade population of hawks and doves because they can reduce risk of injury
  59. Sequential assessment model (Enquist)
    • Benefits of avoiding escalated aggression via assessment form basis of more refined game theory model of aggression
    • - Treats aggressive interactions as sequence of behavioural bouts
    • - Each bout allows assessment of opponent
    • - Sequence involves escalating act types until assessment made
  60. Sequential Assessment Model Predicts:
    • 1. More evenly matched opponents will engage in more escalated contests
    • 2. Where numerous aggressive behavioural acts are possible, these should appear in the same order in all contest
  61. Winner and Loser Effects
    Prior experience across aggressive encounters can also influence the outcome of contests
  62. Winner Effect and Loser Effect
    • Where winning a fight increases the probability of future wins
    • Where losing a fight decreases the probability of future wins
  63. 2. Asymmetry in Resource Value
    • Individual that values resource most more likely to play hawk
    • e.g. Temeles with marsh hawks
    • e.g. Austad with Bowl and Doily Spiders
  64. 3. Arbitrary asymmetries
    • asymmetries that aren't connected to RHP or resource value
    • - Rules for settling disputes among conspecifics
    • - Adaptive: reduce the risk of injury
    • Prior ownership is the most common
  65. Bourgeois
    • Prior ownership
    • Individual that had the resource first usually wins
    • Resident always plays hawk
    • intruder always plays dove
    • Readility invades HAWK/DOVE - become ESS by reducing costs of injury
    • e.g. Davies suggested these moths were bourgeois. Stutt and Willmer disputed that
    • e.g. Baboon mating and feeding
  66. Value of refined game theory models
    • enhanced understanding of behaviour
    • organize empirical findings
    • generate testable hypotheses
  67. L11 To express adaptive behaviour, animals must:
    • 1. Detect: stimuli in environment that warrant a response
    • 2. Process and intergrate: environmental info
    • 3. Carry out behaviour: that best suits environmental conditions

    Must happen rapidly
  68. Living organisms respond to external stimulation how?
    • Neurons
    • Specialized cells that receive and transmit signals
    • Signal via propagation of action potentials
  69. Action Potentials
    • electrochemical signals - travel along neurons
    • electrically charged ions
    • organized into nervous system
  70. Nervous Systems
    • Allows intergration and processing
    • allows specializations
  71. Excitatory event
    • Depolarization of membrane
    • at threshold of excitation -55mV
  72. Sensory receptors and types
    • Transduce environmental energy into electrical impulses
    • thermoreceptors
    • mechanoreceptors
    • chemoreceptors
    • magnetoreceptors
    • electroreceptors
    • photoreceptors
  73. Sense organs
    Multiple receptor cells and accessory structures organized together
  74. Why multiple receptor cell?
    • Insurance against damage
    • Protection from refraction
    • Increased sensitivity and acuity
    • Greater field of response
    • Allows specialization of cells within
    • Definition of neighbouring fields
  75. Afferent fibers and Sensory Interneurons
    convey signals from receptors to CNS

    • Receive input from receptor cells, make interconnection with other sensory interneurons
    • Responsible for preliminary processing
    • - each interneuron fires or doesn't
    • - decision to fire determined via summation of all inputs to cell
  76. Signal received may be
    • Excitatory: depolarize membrane toward threshold of excitation (inc. prob. firing)
    • Inhibitory: Hyperpolarize membrane away from threshold of excitation (dec. prob. firing)
  77. Summation of signals by
    • Spatial summation: net effect of all excitatory and inhibitory inputs over entire surface of cell
    • Temporal summation: net effect of all inputs over time
  78. Central Decoders
    • Higher level of integration of inputs from multiple afferent pathways
    • Formulate a decision based upon temporal and spatial summation of all excitatory and inhibitory inputs
    • give rise to efferent pathways
  79. Efferent Fibers and Motor interneurons
    Convey signals from CNS to effectors

    • - Receive input from CNS
    • - Make interconnections with other motor interneurons facilitating coordinated action of opposed effectors
    • - Send projections to motor neurons
  80. Motor neuron
    • innervate musculature
    • trigger muscle contraction via propagation of action potential
  81. Exceptions to the idealized system exist of neuron pathways
    e.g. cockroaches and noctulid moths. Skip CNS/decoders and motor interneurons (initially)
  82. Accelerating neural transmissiong
    • Invert: giant fibers
    • Vert: myelination and saltatory conduction
  83. Studying Neurobiology of Behaviour 4#
    • 1. Neural Recording
    • 2. Neural Stimulation
    • 3. Ablation
    • 4. Diagnostic Imaging
  84. Neural recording
    • implant microelectrodes in/beside neurons 
    • record activity in response to certain stimuli
  85. Neural Stimulation - Wilder Penfield/Brender Milner
    • Implant microelectrodes
    • stimulate neurons
    • quantify behavioural response

    • Montreal procedure to deal with epilepsy seizure ("I smell burnt toast")
    • Mapped out sensory and motor regions
  86. L12 Ablation
    • Destroy neurons or nuclei
    • quantify effect on behaviour
    • e.g. seed storage and memory in chickadees
    • e.g. Lazaro Spallanzani with bats
  87. Donald Griffin
    • Used ultrasound microphone to record bats
    • Published first conclusive evidence that bats navigate and hunt using echolocation
  88. Echolocation
    • Emission of pulses of high-frequency sound
    • reflect off obstacles and prey
    • received and interpreted by bats as weak echoes
  89. Why don't bats deafen themselves?
    • 1. Muscle in middle ear: Contracts before emission of each pulse. Dampens vibrations of ossicles of middle ear. Achieves attenuation of sound to 1% of original
    • 2. Inhibitory interneurons: Block auditory transmission to brain during signal emission. Attenuate sound to 0.01% original
    • 3. Echo-detector cells in brain: respond maximally to 2nd of two sound pulses
  90. Why don't bats deafen each other?
    • 1. High freq. sound attenuates dramatically with distance: Spacing among bats reduces likelihood of receiving a deafening pulse
    • 2. Bat withing a foraging flock adopt different foraging freq: filter centrally for frequencies resulting from those emitted
  91. Properties of Receptor cells - Roeder
    • A1 cells: Fire in response to low intensity sound; rate of firing increases with intensity of sound; and fire more in response to pulses of sound
    • A2 Cells: fire only in response to very loud sounds
    • A1 & A2: responsive only to high frequencies, and not differentially sensitive to different frequencies
  92. Bat detection - general
    • Highly sensitive A1 fibers begin firing when bat 30m bat away
    • Bat detection threshold is ~3m
    • A1 rate of firing proportional to intensity and therefore distance
  93. How does a moth tell whether bat at front or rear?
    • equal and higher rate of firing - bat to rear
    • equal and lower rate of firing - bat to front
  94. Bat detection - horizontal plane
    • Differential onset and rate of firing of left versus right A1 cell
    • If bat on left, left cell fires sooner and at higher rate than right cell
  95. Bat detection - vertical plane
    • If bat approaching from above, A1 cells will show cyclic change in firing rate as wings beat up and down
    • If bat approaching from below, no cyclic change in firing rate
  96. Antidetection strategy
    • Roeder conducted field studies
    • At a distance, moths oriented/turned away from source of sound
    • Orient so that both RA1 & LA1 have equal and higher rate of firing
    • By flying away from bat, decreases prob. of being detected
    • - Since bat must be within 3m to receive echo
    • - bc back presents smaller target for reflection
  97. Anti-capture strategy
    • Anti-detection strategy not effective if bat within 3m
    • - No oriented turn away
    • - engage in erratic flight patterns
    • makes moths more difficult to capture; masks echo signature; and imposes risk of injury on bat
  98. Physiological basis of evasion
    • When bat within 3 m, SPL of ultrasound high (A2 receptor fire)
    • A2 fibers synapse with interneurons that send inhibitory input to motor neurons innervating wing musculature 
    • causes shutdown and uncoordinated action of wings
  99. L13 Stimulus filtering
    Selective response to certain stimuli from the range of stimuli to which an animal is exposed (product of Umwelt's world)
  100. Receptive field
    Each ganglion cell receives input from multiple bipolar cells which in turn receive input from multiple neighbouring receptor cells (rods and cones)
  101. Hartline's Frog ganglion cells
    - using beam of light and neural recording
    • On cells: delayed but prolonged burst of AP when receptors stimulated
    • On and off cells: immediate but brief burst of AP when light turned on or off
    • Off cells: Immediate and prolonged sequence of AP when light turned off
  102. Hartline's interpretation
    • Ganglion cells provide information about distribution of light and dark spot on retina
    • Produces bitmapped image of object in visual field
  103. Lettvin et al. Frog ganglion Cells
    neural recording with natural objects
    • Sustained-edge detector: respond maximally when elongated edge moves into receptive field and stops
    • Convex-edge detector: max response to small, round objects moving erratically
    • Moving-edge detector: Responsive to moving edges passing into or out of receptive field. ON-OFF CELL
    • Dimming detector: activated by cessation of illumination. Off cell
    • Light intensity detector detector: Response proportional to light intensity. On cell
  104. Lettvin et al. Interpretation
    • Visual representation not Hartline's bitmapped picture of light and dark spots
    • Selective portion of visual stimuli to which frog is exposed
    • Certain networks of cells organized to respond maximally to movement
  105. Why selectively respond to movement?
    • Moving objects shouldn't be ignored (potential prey or predator)
    • Non-moving objects - safely ignore (of no real value). Present no real threat
  106. Function of ganglion cells
    • sustained edge detector: predator
    • convex-edge detector: prey
    • moving-edge detechtor: general arousal
    • Dimming detector: uncertain
    • Light intensity detector: uncertain

    INFORMATION FILTERED and PARTIALLY ANALYZED at level of retina, allowing RAPID response
  107. Sensory responses in Common toads
    • Unlike frogs
    • - No filtering at retina
    • - Distinction (integration) not apparent until neurons of optic tectum
    • Without peripheral stimulus filtering, response slower - suits needs of toads
  108. Ewert T5(2) used neural recording and stimulation, and ablation
    Are prey detectors
  109. Diagnostic imaging
    techniques resolving the structure and activity of intact nervous systems
  110. Electroencephalogram (EEG)
    • Representation of electrical activity in different area of the brain
    • Coarse level of resolution
    • e.g. mallard ducks and Rattenborg
  111. Positron emission tomography (PET)
    • Like cat scan, provide info on morphology, but adds activity
    • Addresses correlation between neural structure, activity, and behaviour
  112. Functional magnetic resonance imaging (fMRI)
    • Resolves how activity of brain regions correlates with expression of behaviour
    • offers insight into previously inaccessible phenomena
    • e.g. females listen with both sides of brain, while males with only one side
  113. Developments in resolving neural structure example papers
    • Developments in resolving neural structure:
    • Livet et al 2007 "brainbow" technique 

    • Developments in resolving neural stimulation modelling 
    • e.g. Markram et al. 2015 cell paper 
    • that are also enhancing our understanding of nervous system function