AP Bio Unit 8 Topic 1

• In the 1970s a group of scientists won the Nobel Prize in Physiology for their discoveries concerning organization and elicitation of individual and social behavior patterns

  • these studies developed the discipline of ethology
• Ethology: the study of how evolutionary processes shape inherited behaviors and the way that animals respond to specific stimuli
• behavior: an animal's response to a stimulus (internal or external)
• behavior includes:

  • nature vs nurture (genetic and environmental factors)
  • allow for survival and reproduction
  • subject to natural selection
• proximate cause: how a behavior occurs or how it is modified

  • what was the stimulus to cause the behavior
  • how does the nurture component affect behavior (how do experiences during growth and development influence the response)
• Ultimate cause: why a behavior occurs (in context of natural selection)

  • how does the behavior help the animal survive and reproduce
  • how does the nature component affect behavior (what is the evolutionary basis of the behavior)
• behavior can be innate or learned
• innate behaviors: developmentally fixed

  • hereditary, born behaviors, do not need to learn them, instinctive
  • experienced during growth with no obvious effectd
• learned behaviors: depend on environmental influence

  • experiences do affect these behaviors
  • high variation in a population
• while behaviors may lean one way more, many behaviors have both innate and learned components
• fixed action patterns (FAPs): a sequence of unlearned acts directly linked to a stimulus

  • actions are unchangeable
  • carried out to completion
  • triggered by a sign stimulus (external cue)
• migration: a regular, long-distance change in location

  • triggered by environmental cues (ie the sun's position)
• signal: a stimulus generated and transmitted from one animal to another; animal communication
• examples of signals: pheromones, stimulus response chain, body movement
• pheromones: chemicals emitted by members of a species that can affect other members of the same species
• stimulus response chains: when a response to a stimulus serves as the next stimulus for a behavior

  • seen in animal courtships
• learning: the modification of behavior based on specific experiences
• imprinting: a long-lasting behavioral response to an individual
• imprinting happens during a sensitive period of development (usually very early in life)
• imprinting occurs on the first individual they encounter
• spatial learning: establishing memories based upon the spatial structure of the animal's surroundings
• some animals form a cognitive map or use landmarks as environmental cues
• associative learning: the ability to associate one environmental feature with another
• social learning: learning through observations and imitations of the observed behaviors
• natural selection favors: behaviors (innate or learned) that increase survival and reproduction

  • foraging: food obtaining behavior
  • animals better at foraging will be more successful in finding food
• mating behaviors: animals can be monogamous or polygamous (polygyny/polyandry)
• sexual dimorphism can result from sexual selection
• cooperative behaviors tend to increase fitness
• altruism: selfless behavior

  • reduced the individuals fitness, but increase the fitness of the rest of the population
• since photosynthesis is critical to a plant's survival, plants can respond to light
• phototropism: a directional response that allows plants to grow towards (and in some cases away from) light
• photoperiodism: allows plants to develop in response to day length; plants flower only at certain times of the year
• plants also have mechanisms of defending themselves against herbivory

  • physical defenses: thorns, trichomes (small plant like hairs)
  • chemical defenses: production of toxic or distasteful compounds
• soil composition can affect plants

  • the pH of soil can affect flower coloring in some plants
  • nutrients are more accessible at certain pH
• What is behavior?


  an animal's response to a stimulus (internal or external)
• what is a proximate cause?


  how a behavior occurs or how it is modified
• What is an ultimate cause?

  why a behavior occurs in the context of natural selection