Animal Behavior Notes

8/26/19 – Introduction, Evolution

  • Physiological mechanisms
  • Genetics
  • Development
  • Evolution
  • Ecology – the scientific study of the interactions among organisms and their environments.

Phenotype = Genotype + Environment Conditions –> Phenotypic Variation in a population is due to both.

  • Heritability: portion of phenotypic variation in a population due to genetic differences between individuals.

8/28/19 – Introduction, Evolution

  • Phenotype = genotype + environment
  • natural selection is a mechanism of evolution, if:
    1. variation (phenotypic) in the population
    2. some of that variation is heritable
    3. interaction w/ the environment
      1. traits that increase survival/reproduction increase in frequency
  • Ex. Peppered moths – birds (predation) is selective force
    • individuals w/ traits best suited for the local environment survive
      • leads to gradual change in genetic makeup of a population (over generations)
        • evolution!
  • what changes is the relative frequency of genes
    • nat. selec. acts on individuals, evol. occurs in pops.
  • Why aren’t organisms “perfectly adapted” to their environment?
    • genetic constraints + lack of genetic variation
      • have to have some sort of variation to begin with
  • Gene flow – migration of individuals from one population to another causing genetic variation
  • Not all evolution is adaptive evolution
    • mutations
    • genetic drift – random event, not natural selection
      • bottleneck is extreme form of drift
  • Fitness – relative # offspring (based on pop.)
  • Group selection doesn’t work because nat. selec. acts on the individual:
    • Infanticide
      • But what’s wrong with Group Selection and doing things “for the Good of the Species”?
        • The pathology hypothesis • The population regulation hypothesis • The quicker reproduction hypothesis

9/4/19 – Sampling Behavior

In-class Lab:

  1. Monkeys (group)
    • Gathering around boxes
    • Trying to open boxes
    • Once box is open they look at what fell out of it while others keep at the boxes
    • Once one box is open they try to walk along rope & open the next
    • A couple separated from the group
    • Eating whats inside the boxes
    • All boxes are open; exploring whats on the ground
    • Each monkey looked into the boxes
    • Some walked away, others still curious
    • Dispersed & returned
    • 2 Fighting over the boxes
  2. After video – list of behaviors:
    • Pacing, looking, walking, eating, digging, grooming, scratching, cuddling/huddling, tail pulling, jumping, climbing, etc.
    • Don’t infer/ try to interpret
    • Anthropomorphism – to give a human-like characteristic to something
  3. Ethology – behaviorism (even in humans)
    1. Ethogram

9/9/19 – Sampling Behavior

  1. Detritus
  2. Focal animal, or continuous sampling
    • Watch 1 animal or subgroup, & record all of its activities for a pre-determined period of time
    • Have to be able to identify individuals, etc.
      • Observe for 20 minutes, record for entire time.
  3. Instantaneous or scan sampling
    • Watch 1 animal or a group at set intervals of time.
    • Don’t necessarily have to be able to identify individuals.
      • Observe for 20 minutes , record occurrence of particular behavior

9/11/19 – Altruism & Social Behavior

  1. Intro
    • Video of ground squirrel
    • Nest building ants Video
  2. Altruism – “self-sacrificing” behavior
    • Lowers the helpers reproductive success while increasing the reproductive success of the individual is helped
  3. How does altruism evolve?
    • Who should you be most altruistic towards?
      • Close relatives
        • You’re helping to have offspring of the next generation with out reproducing on your own
        • Shared genes are passed on. They help rear brothers & sisters (r=0.5), the same as their own offspring if they had them!
        • Altruist helps propagate those genes
    • Coefficient of relatedness = r
      • Probability that any two individuals will share a copy of a particular gene
      • In a diploid species, any given allele has 50% chance of segregating into a given egg or sperm
  4. Definitions
    • Direct selection – acts on traits that promote reproduction
    • Direct fitness – a measure of personal repro (own offspring that survive & repro)
    • Indirect selection (kin selection) – acts on traits that promote success in the reproduction of nondescendant relatives
    • Indirect fitness– a measure of the # of relatives that the altruist helps to survive & reproduce
    • Inclusive fitness – direct + indirect fitness (total measure of genetic success of an individual)
      • Ex. 1 offspring (0.5) = 0.5           3 nieces/nephews (0.25) = 0.75 *Indirect fitness is greater than have children of my own
  5. Hamilton’s Rule
    • When indirect fitness gained by altruist is greater than the direct fitness
  6. Extreme example of altruism
    • Haplodiploidy and the evolution of eusociality in the Hymenoptera
      • Eu  = “true”
      • Haplodiploid
        • Females – diploid (2N)
        • Male – haploid (1 N)
      • Parthenogenesis
        • Fertilized eggs develop as females, unfertilized eggs develop into sterile males
  7. Social Behaviors
    • Social Spider Colony
    • Disadvantages to living in a large social group
      • Lack of resources
      • Pathogens can spread more easily
    • Benefits
      • Cooperation in capturing prey
      • Postponed cooperation

9/16/19 – Social Behaviors

  1. Disadvantages to living in a social group
    • Competing for resources
    • Pathogens spread more quickly
    • Easier to be seen by predators
  2. Benefits
    • Cooperation
    • Defense against predators (selfish herd affect)
    • **unit of selection à individuals (“group selection” is not a thing)
  3. Postponed cooperation – long tailed manakin example
  4. Reciprocity occurs in primates that groom one another
    • Why does recip. not common in animals that have only short-term interactions
      • Not guaranteed that action back
    • Reciprocity in vampire bats ex.
  5. Social interactions overview:
    • Cooperation – helper gains immediate fitness
    • Postponed cooperation – helper gains delayed fitness
    • Reciprocity – helper gains delayed fitness
    • Altruism – helper gains indirect fitness
      • Ex. Pied kingfisher
        • Primary, secondary, and delayed helpers; evolutionary developed
        • Table – primary helper has a inclusive fitness of 0.99 (overall higher)
          • Delayers still contribute
      • Ex. Siberian jays
      • Ex. Carrion crows
    • ** these are actually the exceptions, birds don’t normally do this
  6. What factors have likely been responsible for the evolution of bird species with helper
    • Lack of nesting sites
    • Older birds just aren’t dying
  7. Naked mole rat – a eusocial mammal
    • One “king” and “queen” that reproduce, other “roles” like harem, soldiers, and workers (sterile)
      • Vertebrates
  8. More relatedness in monogamy (cooperation), more likely to see helpers because you’re increasing your indirect fitness when you help those most related to you.

10/9/19 – Communication

    1. Behavioral interactions between animals involve communication
      1. can take place between members of same species (conspecifics)
      2. or diff species (heterospecific)
    2. communicate using signals
      1. sender & receiver must receive signal to be adaptive
      2. eavesdropping
      3. more than one modality
    3. Why do animals communicate?
      1. Sexual advertisement & mate attraction
      2. Parental care (begging, recognition)
      3. Environmental information (predator alarms, food location)
      4. Territory defense, conflict resolution
      5. Social integration (contact calls)
      6. Predator defenses (warning colorations)
        1. Aposomatism
    4. Selection acts on pre-existing traits
    5. Sensory exploitation (taking advantage of the fact that it exists already)
      1. Comm signals originate in actions that activate pre-existing sensory abilities of receivers.
        1. Copepods ex.
    6. Explain the Panda Principle
      1. Selection – how did it operate on pre-existing characteristics to get to where it is now
    7. Why resolve conflicts with harmless threat displays instead of fighting?
      1. Less risky
      2. Wastes energy
        1. Barking gecko
          1. Think about evolution of cheater – eventually you’re going to run into a fight – get selected against eventually.
        2. More dominant paper wasps have more dark patches on their faces
          1. Selection acts to keep the signals honest.

10/14/19 – Communication Continued

  1. Deer bucks compare antler size
    1. UV reflecting skin on lizard
      1. Live to fight another day
    2. Signal deception in Photuris female fireflies
      1. Male photinus flies flash to attract females of their species
      2. Sometimes female photuris will send a signal back, but attack/eat the male instead of mating.
      3. Why do some animals do the wrong thing (get fooled and die)?
        1. Novel Environment Theory
        1. Net Benefit Theory
          1. An adaptation doesn’t have to be perfect
            1. Just has to contribute more to fitness on average compared to other alternative traits
    3. Eavesdropping
      1. Influences the evolution of bird calls

10/16/19

  1. Review
    1. Hypothesis – general
    2. Predictions – specific – suggests experiment “if, then”

10/21/19

  1. Proximate & Ultimate Causation
    1. Why do people like sugary foods?
      1. Tastes good
      2. Energy
        1. Had ancestors that had a selective advantage if they found a sugary fruit.
      3. Proximate Answers
        1.  How genetic-development mechanisms
        1. How neural-hormonal mechanisms
      4. Ultimate Answers
        1. Evolutionary history
        1. Adaptive history
    2. Examples:
      1. Prairie Voles
        1. Selection and adaptation – mate guarding ensure that males will sire all of a female’s offspring
          1. Ultimate Cause (adaptive/survival of the behavior). Evolutionary history = ultimate cause
        1. Hormonal/Nervous System Mechanisms
          1. Vasopressin with V1a receptors – provides male with positive reward
          1. Proximate Cause
    3. Proximate and Ultimate Causes are interconnected
      1. History & internal mechanisms play a part
    4. Two possible explanations for dialect differences?
      1. Learning (from parents) ie. environmental differences
        1. Experience and learning in young males
      2. Genetic Differences (may effect neural mechanisms)
      3. Ex. Study
        1. Lab exper. Raising white crowned sparrows in the lab from both Marin & Berkeley pops.
          1. When raised in isolation, they only twitter not sing.
          1. When exposed to songs of a different dialect than the pop they came from, they’ll learned that one in early development.
          1. Lab-reared White Crowns that only hear the song of another species only make a twittering sound like they did in isolation.
            1. Genes still play a part
        1. Social experience influences song development
        1. Social environment is more important than acoustical…
    5. Proximate mechanisms include neurophysiology and genetic activity
      1. Key sensory inputs àgene activity àchanges in biochemistry àalters neurophysiological mechanisms à learning

10/23/19

  1. Proximate & Ultimate Examples:
    1. Giraffe’s long necks
      1. Proximate ex. (genes, nerves, hormones) – they might have genes that code for the components of having a long neck and are shown during development
        1. During development the vert. extend…
      1. Ultimate – long neck giraffes could reach the leaves & therefore pass on their genes (selection)
  2. Song control systems in Parrots, Hummingbirds, and Oscine Songbirds
    1. Not having to learn the song – saves time & energy
    1. Diagrams of 3 species that have to learn their songs – look mostly the same, which suggests they have a common ancestor – evolved from species that did not have to learn.
  3. Why learn to sing?
    1. Disadvantages
      1. Time & energy spent
    1. Adaptive Advantages
      1. Helps in territorial establishments – they can tell based on their dialect (influenced by environmental factors) who is from where (neighbor recognition)
        1. Territorial success of male depends on how many song types he shares
          1. Aggressiveness of response changes based on what songs they sing (if they sing the same tune, males are more likely to be aggressive)
  4. Males that learn songs (Particular dialects) may be more attracted to females
    1. Females get information about his development history and suitability to a particular habitat
      1. Ultimate Causation (phylogeny)
  5. Females choose males who can copy their tutors

Foraging and Predator Avoidance

  1. Adaptation
    1. Why are some traits maladaptive?
      1. Novel environment
        1. Now present in an environment that they don’t have evolutionary history in
      1. Other reasons
        1. Pleiotropy – one gene causes multiple phenotypic effects (not benefit theory)
        1. Genetic Drift
          1. Abiotic event wipes out a portion of the population, and the gene pool changes (ex. Tree falls, takes out a bunch of blue flowers, now there’s a greater pop of black flowers.
        1. Gene Flow
          1. Previously isolated pops. Bring new genes into the area
            1. If they aren’t adapted/suited to that new pop., we may see maladaptive traits
          1. Spider Ex. In Texas
            1. Harsh environment, low predators, more aggressive
            1. Non-harsh environment, more predators, less aggressive (more cautious)
          1. In Arizona, the riparian pop. is much more aggressive and less cautious than predicted
          1. Hypothesize that gene flow from desert pop to riparian responsible
            1. Build a fence between pops. to prevent gene flow

10/28/19

  1. Proximate & Ultimate Review
    1. Q1 – B, Q2 – A
  2. Sexual Cannibalism
    1. Australian redback spider
      1. Males are much smaller than females
      1. Males have two specialized legs called palps that transfer sperm
      1. Female begins to feed on male during courtship
    1. Why do females cannibalize males during copulation?
      1. Consider 3 hypotheses:
        1. Mistaken prey
          1. Females mistake males for prey
            1. Compare female behave. when feeding on prey to her behave. when eating mate
            1. You would predict…females would sometimes attack males as soon as they enter the web.
        1. Mate rejection
          1. Females eat males that are unsuitable mates
            1. You would predict…cannibalized males would be smaller and produce less offspring than non-cannibalized males
        1. Hungry Lover
          1. Females eat males because they are hungry
            1. To test…compare cannibalism rates of two groups of females: one group feeds naturally, while the other has its diet supplemented
            1. You would predict…females would be more likely to cannibalize if their diet has not been supplemented
      1. Proximate explanation for female cannibalism
        1. Female eats the male bc. he dangles his abdomen in front of her jaws – triggers physiological response (predatory)
      1. Ultimate explanation
        1. The female gains nutrients from eating the male
    1. Male sacrifice –
      1.  paternal investment hypothesis
        1. Consuming the male would significantly increase the number and mass of the eggs in the female’s egg sac.
          1. Increases the chance of eggs’ survival
      1. Nuptial Gift hypothesis
        1. If correct, then we’ll see that the male fathers more offspring than non-cannibalized males.
          1. Q11 – A

10/30/19 – Foraging and Predatory Behavior

  1. Mobbing gulls
  2. Parsimony
    1. The simplest/fewest amount of steps for an evolutionary event to occur is often times the correct one
    1. Graph on the left is more parsimonious
  3. Black-headed gull ex.
    1. They evolved to nest on cliffs—hypothesis is that they’d no longer have a need to mob
    1. Convergent Evolution – see the same behavioral trait in two completely unrelated species
    1. Vs. Divergent evolution
  4. Social Defenses
    1. Disruptive patterning – causes the predator to be confused
    1. The Conclusion Effect
    1. The Dilution Effect – individual probability of being attacked decreases as your group size increases
      1. Mayflies – flood the predators by hatching less frequently
    1. Many eyes hypothesis – turkeys
  5. The Social Herd
    1. animals in the center of a herd may be more inaccessible to predators
      1. indirect selection
      1. usually you see the strong in the center, the old, sick, weak, etc get pushed to the outside
  6. Game Theory – the success of an individual depends on what its competitors are doing
    1. Penguin ex.
  7. Distraction Display
    1. Direct attention of predator away from vulnerable prey to another prey that is more likely to escape
    1. Broken wing act
    1. Probably protecting kin nearby
  8. Crypsis (camouflage) – matching/mimicking background to hide from predator
    1. Examples: octopus, flounder, frog-fish (aggressive mimic – camouflage to capture prey)
      1. Aggressive mimic – mimic background to hide from prey
        1. spiders that look like ants
  9. Aposematism – bright coloration that gives a “warning” of toxins
  10.  Mimicry
    1. Batesian mimicry – a harmless species mimics a harmful one
      1. Monarch butterfly toxins on a predator
        1. If the monarchs feed on milkweed (which has a cardiac toxin)
        1. Model vs. Mimic
          1. More models than mimics (10% or less) because it all depends on the learning of Blue Jays – if mimics were more common, blue Jays would eat them, not get sick, and keep eating them
    2. Mullerian mimicry – is where two or more unpalatable species resemble each other
      1. What the purpose if you’re already toxic? Amplifies signal

11/4/19

  1. Why behave conspicuously?
    1. Ex. Fly mimicking jumping spider
      1. If you put a housefly’s wings on this fly, the spider will eat it
      2. If you put this fly’s wings on the housefly, the housefly doesn’t display those jumping behaviors and still gets eaten.
    2. A Stotting Springbrook
      1. I’m not worth the energy to try and catch
      2. Signal of unprofitability is the correct hypothesis/prediction
        1. Cheetahs abandon hunts more when gazelles stot
  2. Optimality Theory
    1. Benefits outweigh the cost
      1. Which of these phenotypes are adaptations (graph)? (fitness costs vs. phenotypes) – not phenotype Z, the costs outweigh the benefits here.
      2. Over time, X will last longer over time than W and Y
        1. It is the only adaptation in this graph, it has the greatest amount of benefits that outweigh the costs
    2. Hard to get these results in reality
    3. Reto Zach’s observations for foraging crows:
      1. Is this an optimal way to forage?
        1. If crows are foraging optimally then…
          1. Drops less than 5 meters should have lower breakage rates, etc.
    4. The Optimal Foraging Theory predicts that an animal should behave in a way that
      1. Maximizes benefits,
      2. Minimizes costs,
      3. So max. net energy gain
      4. The central assumption is:
        1. The more net energy an individual gains, the greater the reproductive success
      5. How do we best determine profitability?
        1. Profitability of prey = energy gained per unit handling times
          1. Young garden skinks lower their foraging success in order to reduce the risk of predation
            1. Presence of predator might influence optimal foraging behavior
              1. Predation is the stronger pressure, not hunger
              1. Its not just energy vs. time like we predict
    5. Alternative Foraging Strategies
      1. Genetically based strategies maintained by Frequency-Dependent selection
      2. Condition strategies based on environmental conditions
      3. Geographical separation and divergence

11/13/19

  1. Alternative Foraging Strategies
    1. Genetically based strategies maintained by Frequency-Dependent Selection
      1. Frequency-Dependent Selection –
        1. Being rare can be an advantage, but it’ll change over time due to selection pressure—predators know to eat orange moths, so the blue ones will be safe at first. Over time, the blue will become more frequent because the orange ones are getting eaten; the relationship (frequency) is an oscillation
    2. Conditional strategy – an inherited mechanism that gives an individual the ability to be flexible
      1. Ruddy Turnstone Bird ex. – push over seaweed, turn stones over, probe in the mud
  2. The Evolution of Reproductive Behavior
    1. Males are generally more ornate and brightly colored, females are more bland and blend in with their environment
      1. Bowerbird ex.
        1. Males build elaborate bowers, females choose the best one
    2. Sexual Selection
      1. Elaborate costly traits lower survival, but enhance the ability to mate are sexually selected traits.
      1. Bower birds – may be indicative of brain size
        1. Direct correlation between cognitive ability and mating success
        1. Variance in reproductive success is greater for males than females in the bowerbird
    3. Operational Sex Ratio
      1. Generally, males have a greater ration than females (females = 1 and done, while males attempt to mate with many to increase fitness)
        1. Females – goal is to find the best male
        1. Males – goal is to find as many females to mate with as possible
          1. Increases competition between males
    4. Parental Investment takes many forms