Animal Behavior (Ch. 51)

Transcription

1 Animal Behavior (Ch. 51)

2 Behavioral Ecology Two types of questions: Proximate questions: Focus on environmental stimuli that trigger behavior and physiology behind response How? Ultimate questions: Focus on evolutionary significance of the behaviors Why?

3 Proximate Questions Proximate questions address the mechanisms that produce a behavior. The environmental stimuli, the genetic and physiological mechanisms that make it possible Example- How does an animal carry out a particular behavior?

4 Red-crowned cranes breed in spring and early summer. Choose the proximate explanation: A. Breeding is most likely to be successful in spring and early summer. B. Increasing day length triggers the release of breeding hormones. C. Ample food is available for chicks at this time.

5 Ultimate Questions Ultimate questions address the evolutionary significance of a behavior How a behavior increases the evolutionary fitness of the animal demonstrating it, helping it to survive and reproduce in its environment. Example- Why does the animal show this behavior?

6 What is evolutionary fitness?

7 Adaptive behavior An adaptive behavior increases an individual s evolutionary fitness relative to other individuals in the population. (Similar to a physical adaptation)

8 Red-crowned cranes breed in spring and early summer. Choose an ultimate explanation: A. Breeding is most likely to be successful in spring and early summer. B. Hormonal changes in the spring trigger breeding behaviors. C. Breeding is triggered by the effect of increased day length on the birds photoreceptors.

9 Sexual cannibalism In some species, one sex (usually the female) consumes the other during sexual reproduction. Praying mantis Australian redback spider Scorpion

10 Australian Redback Spider Praying Mantis

11 Choose a proximate explanation for female cannibalism: A. The female eats the male as he dangles his abdomen in front of her jaws. B. The female can produce a larger egg sac if she eats the male. C. The female gains nutrients by eating her mate.

12 Choose an ultimate explanation for female cannabilism: A. The female eats the male because he dangles his abdomen in front of her jaws. B. The female gains nutrients from eating the male. C. The female copulates longer while eating her mate.

13 Choose a proximate explanation for male self-sacrifice: A. The male s somersault in front of the female s jaws is triggered when he inserts a palp in the female s sperm receptor. B. The male is providing nutrients to his offspring. C. A male that is cannibalized fathers twice as many offspring.

14 Choose an ultimate explanation for male self-sacrifice: A. The male increases the length of copulation by sacrificing himself. B. The male s selfsacrifice is an innate, genetically programmed behavior. C. The male is providing nutrients to his hungry mate.

15 Further testing - What experiment might you conduct that would narrow down the ultimate cause choices above?

16 Behavioral Ecology Behavior= What an animal does and how the animal does it Ethology= Study of how animals behave, particularly in their natural environment

17 Behavioral Basics

18 Behavioral Ecology Based on idea that animals behave in such a way as to maximize fitness Idea only works because genes influence behavior (nature) Fitness= Passing on genes to offspring Animals modify behavior to keep ratio of energy intake to energy expenditure high Ex. chipmunks

19 Review: Optimal Foraging Amount of food taken in will be in proportion to amount of energy spent What is the relationship to fitness?

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21 Scientific Research

22 Ethologists Nikolaas Tinbergen Nobel Prize- Eliciting behavior patterns in animals Four Questions Mechanical- How does the behavior occur? Developmental- How has the behavior changed? Evolution- How did this behavior come about? Fitness- Why is this behavior beneficial?

23 Ethologists Karl von Frisch Discovered the communication dance of bees Round dance meant food was close Waggle dance showed distance and direction of food

24 Dance of the Bees

25 Konrad Lorenz Worked with greylag geese and discovered imprinting

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27 Ethnologists

28 Innate Behaviors

29 Fixed Action Pattern (FAP) Sequence of unlearned, unchangeable behaviors Usually carried to completion once started Triggered by external event = sign stimulus Ex. Stickleback fish- Tinbergen

30 Fixed Action Patterns Tinbergen's Experiment

31 Fixed Action Patterns (FAP) Egg rolling experiment

32 Directed Movements Taxis Change in direction Automatic movement toward (positive taxis) or away from (negative taxis) a stimulus Kinesis Phototaxis Chemotaxis Geotaxis Change in rate of movement in response to a stimulus

33 Complex Innate Behaviors Migration Migratory restlessness seen in birds bred & raised in captivity Navigate by sun, stars, Earth s magnetic fields

34 Imprinting- Innate & Learned Learning to form social attachments at a specific critical period Both learned and innate components

35 Imprinting Generally irreversible Has critical period/sensitive period = limited time when behavior can be learned Ex. geese- Konrad Lorenz

36 Review Optimal foraging Scientists - Von Frisch, Lorenz, Tinbergen Innate Behaviors FAP Directed movements Migration Imprinting

37 Learned Behaviors

38 Learning Modification of behavior based on experiences Habituation= Lack of response to stimuli that give no information Spacial Learning= Based on experience with structure of environment Associative Learning= Connecting one event with another Classical Conditioning Operant Conditioning

39 Learning: Habituation Cry wolf effect Decrease in response to repeated occurrences of stimulus Enables animals to disregard unimportant stimuli Why? Ex. falling leaves not triggering a response in baby birds

40 Spatial Learning Memory reflected by environment s spatial structure Ex. Digger wasps, hidden food sources, etc.

41 Associative Learning Classical conditioning- Unconnected stimulus associated with specific outcome Ex. Pavlov s salivating dogs and a bell Operant conditioning- Trial and error; behavior associated with specific outcome Ex. Skinner s mouse and food lever

42 Operant Conditioning

43 Social Behaviors

44 Social Behaviors Interactions between individuals develop as evolutionary adaptations communication/language, agonistic behaviors, dominance hierarchy, cooperation, altruistic behavior

45 Agonistic Behaviors Threatening & submissive rituals symbiotic, usually no harm done ex. territoriality, competitor aggression

46 Dominance Hierarchy Social ranking with a group pecking order

47 Cooperation Working together in coordination Ex. pack of African dogs hunting a wildebeest, white pelicans herding fish

48 Altruistic behavior Reduces individual fitness, but increases fitness of recipient Increasing survival of close relatives passes familial genes on to the next generation

49 Animal Signals Visual Auditory Chemical Tactile/touch

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