1. Chapter 51
Behavioral Ecology

2. What is Behavior? Everything an animal does & how it does it.
To study behavior you must observe behaviors & study the mechanisms underlying the behavior.
When studying animal behavior, you should ask both proximate and ultimate questions…

3. Proximate Questions
These questions focus on the environmental stimuli that trigger a behavior and the genetic, physiological & anatomical mechanisms that power that behavior.
These are “how” questions…

4. Ultimate Questions
These questions address the evolutionary significance of a behavior.
These questions typically suppose that a behavior increases fitness somehow.
These are “why” questions…

5. Ethology: The scientific study of animal behavior.
Supposes that to understand any behavior, you must be able to answer the following questions:
1.) What is the mechanistic basis of the behavior (chemical, anatomical,etc)?
2.) How does the development of the animal influence the behavior?
3.) What is the evolutionary history of the behavior?
4.) How does the behavior contribute to survival & reproduction (fitness)?
2 types of behavior frequently studied are fixed action patterns and imprinting…

6. Fixed Action Patterns
Definition: a sequence of behavioral acts that once initiated are usually carried to completion (unlearned & essentially unchangeable).
Sign stimulus: external stimulus that triggers the FAP

7. Example of FAP
Male 3-spined stickleback fish attacks other males that invade its nesting territory.
Sign stimulus: red underbelly of male stickleback.
Males will assume attack posture as long as some red is present – even with fake models!

9. Causes of Behavior (FAP)
Proximate cause: red belly of intruding male acts as a stimulus that “releases aggression” in male
Ultimate cause: Chasing away other males decreases the chance that eggs laid in his nesting territory will be fertilized by another male ---- increases his own fitness.

10. Imprinting
Definition: type of behavior that involves both innate & learning components & is generally irreversible.
Sensitive period: the limited period of time during which imprinting is possible.

11. Example of Imprinting
Young geese follow their mother – they “imprint” on her and learn her behaviors.
Sensitive (critical) period is the first few days of life – young geese will imprint on the first object they see that moves toward & away from them – they then follow it as their “mother.”

13. Imprinting in Geese – why?
Proximate cause: During sensitive period, young geese observe mother moving away from them & calling (this is their imprinting stimulus and they will respond to anything – not just a geese – during that time).
Ultimate cause: geese that follow & imprint on their mother receive more care & learn more skills & have a greater chance of surviving.

14. Genetic Components of Behavior
Innate Behavior: developmentally fixed & under strong genetic influence.
Many animal movements are under genetic influence…

15. Kinesis Definition: change in activity rate in response to a stimulus
Sow bugs survive best in moist environments. When exposed to dry environments, they become more active – increases their chance of finding a moist area.

17. Taxis
Definition: an automatic movement toward (positive taxis) or away (negative taxis) from a stimulus.

18. Animal Communication
Animals communicate by using visual, auditory, chemical, tactile AND electrical signals – many of these are under genetic control.

19. Chemical Communication
Pheromones: chemical substances that are emitted by animals --- communication through odors.
Production & response is genetically controlled.

20. Town ant workers following an artificial trail made by drawing a very dilute solution of the ant's trail pheromone methyl 4-methylpyrrole-2-carboxylate.   Only 0.33 mg of this pheromone would draw a detectable trail around the world.

21. Auditory Communication
In most insects, mating songs are genetically controlled.
Insects raised in isolation can sing their species unique song.
With birds, songs are usually learned (at least in part).

22. Behavior is not all Genetically controlled!
The environment interacting with an organism’s genotype influences the development of behaviors.

23. Learning
Definition: the modification of behavior based on specific experiences.
Examples of learning…

24. Habituation
Definition: loss of responsiveness to stimuli that convey little or no information.
If the stimulus doesn’t affect the survival of the organism, they stop responding.
Ultimate cause: increase fitness by allowing an animal’s nervous system to focus on stimuli that ARE conveying info.

25. Spatial Information
Definition: modification of behavior based on experience with the spatial structure of the environment (location of nests, hazards, food, mates).

26. Associative Learning
Definition: ability of animals to associate one feature of the environment with another.
Examples: classical and operant conditioning

27. Classical Conditioning
Definition: an arbitrary stimulus is associated with a reward or punishment
Famous experiment: Pavlov’s dogs. Dogs associate ringing of bell with food (reward)…begin to salivate when they just hear a bell.

30. Operant Conditioning
An animal learns to associate one of its own behaviors with a reward or punishment and then tends to repeat or avoid that behavior.
(Predators often learn to associate prey with painful experiences or bad tastes)
B.F. Skinner did some work with this…

33. Concept Check
How might associative learning explain why unrelated distasteful or stinging insects have similar colors? (Think why this would be an advantage for the insects in terms of predators learning).

34. Behavior can Evolve through Natural Selection
1.) There is variation in behaviors (feeding behaviors, attack behaviors, escape behaviors, etc).
2.) This variation depends on environment and animals survival.
3.) Some behavioral components are genetic - passed down from parent to offspring.
*Read pages on this topic. Discusses experiments conducted on garter snake and spider behavior.

35. Natural Selection favors Behaviors that Increase Fitness

36. Foraging (obtaining food) Behavior
1.) Optimal foraging theory: foraging behavior is a compromise b/w the benefits of nutrition and the costs of obtaining food.
2.) According to this, natural selection should favor behavior that minimizes the energy costs of foraging and maximizes the food benefits.
Example: Crow experiment (page 1122)

37. Mating Behavior & Mate Choice
1.) Mating behavior is the result of sexual selection.
2.) As other behaviors, must enhance reproductive success (fitness).

38. Mating Systems
1.) In most species, mating is promiscuous – no strong pair bonds or relationships.
2.) Monogamous: one male mating with one female
3.) Polygamous: an individual of one sex mating with several of the other.
a.) Polygyny: one male w/ several females
b.) Polyandry: one female w/ several males

39. Influences on Mating systems
1.) The needs of the young: if young require a lot of care, male may increase fitness by helping a single mate than by seeking other mates.
2.) Certainty of paternity: is low in most species with internal fertilization (even monogamous ones) b/c the acts of mating and birth are separated over time – this could be why exclusively male parental care occurs in very few species of birds & mammals.

40. Influences on Mating systems cont’d…
a.) Males of many species with internal fertilization try to guard females, remove sperm from female reproductive tract b/f mating, etc.
b.) W/ external fertilization, if parental care happens at all, just as likely to be male as female.

41. Sexual Selection & Mate Choice
Intersexual selection: members of one sex choose mates on the basis of particular characteristics of the other sex.
Intrasexual selection: competition among members of one sex for mates.

42. Agonistic behavior
Definition: ritualized contest that determines which competitor gains access to a resource such as food or mates (intrasexual selection).
The winner isn’t always the only successful one! Many species have multiple behaviors or morphologies that make them successful.

43. On to Altruism!
What?

44. Altruism
Definition: altruistic behaviors are those that reduce an organism’s individual fitness but increase the fitness of another individual in the population (this is “selflessness”).
Examples: grounds squirrels give alarm call, societies of honeybees or naked mole rats.

46. Why would an organism be altruistic???

47. Inclusive Fitness
Definition: The total effect an individual has on passing on its genes by producing its own offspring AND by providing aid that enables close relatives (who share may of those genes) to produce offspring.
So, being altruistic (helping out your relatives) increases your fitness.
Natural selection that favors altruistic behaviors that enhance the reproductive success of relatives is called kin selection.

48. Reciprocal Altruism
Definition: the idea that if you help someone out, they will return the favor. Used to explain altruistic behavior b/w unrelated individuals.
1.) Usually limited to organisms that live in stable social groups.
2.) Occurs most often in groups where individuals are likely to meet again and where there would be negative consequences for not returning a favor.
3.) Tit for tat behavioral strategy: an individual treat another in the same way it was treated the last time they met. If not met with cooperative/altruistic behavior, individuals retaliate.

49. Evolution & Human Culture
Culture: a system of information transfer through social learning or teaching that influences the behavior of individuals in a population. Humans aren’t the only ones with cultures!
Sociobiology (relates human culture to evolutionary theory): certain behavioral characteristics exist because they are expressions of genes that have been perpetuated by natural selection.