MCB 462 Final Exam

• Basic Functions of Life

  • Acquisition of Resources
  • Defense
  • Reproduction
• Critical Physiological Functions


  • Homeostasis: maintains internal conditions around a set physiological point.
  • Thermoregulation
  • Osmoregulation
  • Circulation
  • Respiration
  • Reproduction
  • Nutrition
• Decision


  Behavioral choice based on cost-benefit analysis. Arises from integration of: Sensation, Internal State, Memory of Experience
• Behavior


  Involves movement, secretion (and possibly endocytosis)
• Drive


  Long-term arousal level of a set of behaviors that normally act to accomplish functions important to the fitness of an organism. (could be thought of as "Homeostatic Goal")
• Fitness


  The ability of animals to pass on its own genes (this definition is expanded in Inclusive Fitness Theory).
• Motivation


  The level of arousal of a behavior or set of behaviors that can be measured in response to stimulation.
• Sign stimuli and releasers

  Sensory stimuli that can elicit specific behavior patterns.
• Feature detection


  Perception of special features in the environment.
• Memory for experience


  • Habituation
  • Sensitization
  • Associative Learning
• Proximate Cause


  The direct/immediate cause, which is temporally close to the observed behavior. When we think of behavior as movement/secretion that is triggered by stimuli/memory, we are thinking of proximate causes. Sensation (feature detection), motivation, and experience are proximate causes.
• Ultimate Cause


  An evolutionary cause. They relate to how behavior is shaped by fitness, which is the ability of an animal to pass on its genes. The same behavior will have a proximate and ultimate cause.
• Question: what are the proximate and ultimate causes of the startle response?
• Fixed Behaviors


  Patterns are very stereotyped and are largely generated centrally with little sensory feedback.
• Non-fixed Behaviors


  Patterns are dependent on sensory feedback. They allow the animal to interact adaptively with the environment.
• Mixed Behaviors


  Mixture of centrally patterned movements that are directed by drives, organized by motivation, and fine-tuned by sensory inputs.
• Interlocking Releasers


  Complex behavior can be broken down into sequences of behavioral subroutines that are cued by environmental and internal signals.
• Ticks!


  • Become sensitive to light -> Climb up a vertical surface, waiting for next stimulus -> Animal walks by, secreting butyric acid -> tick moves (along chemical gradient), jumps down and latches on -> Animal is radiating heat -> tick burrows toward warmth (along heat gradient), finds bare skin, drinks blood -> Tick consumes enough blood to produce eggs -> detaches from the animal
• Question: What happens if heat precedes butyric acid?
• Altruism


  A costly act by one individual that benefits another. Altruistic behavior can evolve through Kin selection, Reciprocal altruism
• Inclusive Fitness Theory


  The fitness of an animal is the ability not only to pass on its own genes to children, but to preserve them in close relatives
• Reciprocal Altruism


  A costly act performed by one animal for another's benefit, with the expectation of receiving a reciprocal costly act.
• Tit for Tat


  A game of repeated encounters. Rules: B >B+C> 0> C and B+C > B/2. Winning Strategy: Do unto others as you would do unto you…but then do unto them like they did to you the last time!
• In general, 2 players that initially cooperate, benefit in the long run
• Kin selection


  A major factor in determining altrusitic behavior is the relatedness of individuals (r). The greater the relatedness, the higher the cost an individual is willing to bear (for lower benefit) (r> C/B which is Hamilton's rule)
• Haploid


  Single set of chromosomes in the cell/organism
• Diploid


  Two sets of chromosomes
• Haplodiploidy


  A sex determination system in which males develop from unfertilized eggs and are haploid, and females develop from fertilized eggs and are diploid
• Look at the figure to the left which shows a hypothetical diploid species which has 1 chromosome with 4 genes.
• Each parent has two copies (sets) of this chromosome, as do each of the children, as they are all diploid
• The genes are mixed and matched when they reach the children, but each offspring receives one copy of a gene from the father and one from the mother.
• Relatedness is the fraction of shared genes.
• What fraction of each siblings genes is shared with the mother or father? How about with each other?
• What fraction of a siblings gene would be shared with a grandparent, uncle, first cousin?
• Haplodiploid Kin-Selection


  A Different Way of Calculating Relatedness
• Relatedness between 2 sisters (D1,D2) in haplodiploid species: 0.75
• Relatedness between sister (D2) and brother(S1) in haplodiploid species: 0.25
• 5 Rules for the Evolution of Cooperation

  • Kin selection
  • Direct Reciprocity
  • Indirect Reciprocity
  • Network Reciprocity
  • Group Selection
• Question: What kind of environment might support direct reciprocity, but not indirect reciprocity?
• Paramecium


  A free-living single-celled animal. If tapped on the head (anterior end), backs up. If tapped on the bottom (posterior end), swims faster.