Behavioral Biology Chapter 54

1. Behavioral BiologyChapter 54

2. Approaches • Behavior:the way an animal responds to stimulus in its environment • Two components of behavior • Immediate cause • Evolutionary origin • Proximate causation:“how” of behavior • Measure: hormone level - testosterone • Impulse of nerve signal

3. Approaches • Ultimate causation: “why” of behavior • Determine how behavior influences reproductive success or survival • Controversy: • Is behavior determined by individual’s genes • Or by learning and experience • Nature or nurture

4. Innate behavior • Innate behavior:instinctive, does not require learning • Preset paths in nervous system • Genetic: fixed action pattern Example: goose replacing an egg from her nest • Egg retrieval behavior is triggered by a sign stimulus • Once pattern begins, it goes to completion; even if the egg is removed

5. Innate Behavior • Male stickleback fish will attack anything with a red underside • Does not need to be a fish • Supernormal stimuli: given a choice: animals respond to a larger stimuli over a normal size stimuli

6. Behavioral Genetics • Artificial selection data has shown that behavioral differences among individuals often result from genetic differences • Genetics of learning

7. Behavioral Genetics • Mice: fosB gene • Determines whether female mice nurture their young • Both fosB alleles disabled: ignore young • Normal mothers: protective maternal behavior • Protein expressed by fosB activates other enzymes and genes that affect neural circuitry within the hypothalamus

8. Behavioral Genetics • fosB present: mother cares for her young • fosB absent: young are ignored and eventually die

9. Behavioral Genetics Vasopressin receptor • Prairie voles are monogamous • Montane voles mate and do not work together to raise young • Different response to oxytocin and vasopressin • Peptide receptor sequence and location in brain different

10. Learning • Learning: altered behavior as a result of previous experiences • Nonassociative learning: does not require an animal to form an association between two stimuli or between a stimulus and response • Habituation: decrease in response to a repeated stimulus • No positive or negative consequences

11. Learning • Associative learning: association between two stimuli or between a stimulus and a response • Conditioned behavior through association • Two major types: • Classical conditioning • Operant conditioning • Differ in the way associations are established

12. Classical conditioning: the paired presentation of two different kinds of stimuli with an association formed between them • Pavlovian conditioning • Unconditioned stimulus: meat • Unconditioned response: salivating • Conditioned stimulus: bell ringing • Conditioned response: After time, the dog salivates with only the ringing of the bell

13. Learning • Operant conditioning: animal learns to associate its behavior response with a reward or punishment • B.F. Skinner • Trial and error learning • Today it is believed that instinct guides learning by determining what type of information can be learned through conditioning

14. Development of Behavior • Parent-offspring interactions influence cognition and behavior • Imprinting: formation of social attachment to other individuals or develop preferences that will influence behavior later in life • Filial imprinting: attachment between parents and offspring • Konrad Lorenz

15. Development of Behavior • Instinct and learning may interact as behavior develops • White-crowned sparrow males sing species-specific courtship song during mating • Genetic template: innate program to learn the appropriate song • Can not learn the song unless they hear it at a critical period in development

16. Development of Behavior • Exposed to own species song during development • Not exposed to song

17. Orientation and Migratory Behavior • Orientation: goal-oriented movements • Track stimuli in the environment • Homing instinct • Taxis: movement toward or away from a stimulus • Kineses: more or less active when stimulus intensity increases

18. Orientation and Migratory Behavior • Migrating animals must be capable of orientation and navigation • Navigation: the ability to set or adjust a bearing • Sun and stars: general direction • Earth’s magnetic field: specific path • Information from the stars overrides the magnetic information if they conflict

19. Orientation and Migratory Behavior Migratory behavior of starlings

20. Communication • Communication can play a key role in behaviors • Among members of the same species • Between species • Successful reproduction depends on appropriate signals and responses • Stimulus-response chain: behavior of one individual releases a behavior by another individual

22. Communication Long-distance communication • Pheromones: chemical messengers • Sex attractant • Males have sensory receptors • Some insect pheromones can be detected as far as 7km away • Acoustic signals • Vocal calls, wing clicking • Light signals: firefly

23. Communication • Communication facilitates group living The waggle dance of honeybees

24. Communication • Chimpanzees and gorillas can learn to recognize a large number of symbols and use them to communicate abstract concepts • Complexity of human language • Differences are superficial • 3000 languages draw from the same set of 40 consonant sounds

25. Behavioral Ecology • Behavioral ecology: study of how natural selection shapes behavior • Adaptive significance of behavior • Reproductive success, fitness • Questions asked • Is behavior adaptive • How is it adaptive • Enhance energy intake, increase mating success, decrease predation

26. Behavioral Ecology Foraging behavior can directly influence individual fitness • Foraging involves a trade-off between food’s energy content and the cost of obtaining the food • Optimal foraging theory: natural selection favors individuals whose foraging behavior is energetically efficient

27. Behavioral Ecology Optimal foraging makes two assumptions • Natural selection will only favor behavior that maximizes energy acquisition if the increased energy reserves lead to increases in reproductive success • Avoid predators • Find mates

28. Behavioral Ecology Optimal diet. The shore crab selects a diet of energetically profitable prey

29. Behavioral Ecology Territorial behavior secures resources • Home range: where the animal lives and forages; defends territory • Defense against intrusion by other individuals • Birds sing or display to signal their territory; energetically costly • Benefit: increased food intake

30. Sexual Selection • Reproductive strategies: decisions about mating • How many mates to have • How much time devoted to rearing offspring • How much energy devoted to rearing offspring • Evolved partly in response to cost of reproduction...efficient strategies in a niche

31. Sexual Selection Advantage of male mate choice. Male Mormon crickets choose heavier females as mates, larger females have more eggs • Male Mormon crickets use 30% of their body weight making up a spermatophore (nutritive protein containing packet) for the female

32. Sexual Selection • Mating systems reflect adaptations for reproductive success in a niche • Energy costs, food resources, nest sites, distribution of opposite sex • Mating systems • Monogamy: one male one female • Polygyny: one male many females • Polyandry: one female many males

33. Sexual Selection • Mating systems influenced by ecology • Territory size • Needs of offspring • Both parents: monogamy • Altricial: offspring require long care • Precocial: little care required • Polyandrous systems: males usually care for the young, females mate with many males

34. Altruism • Altruism: the performance of an action that benefits another individual at a cost to the actor • Question: if altruism imposes a cost to an individual, how could an allele be favored by natural selection? • Group selection: rare • Among groups: leads to a decrease in allele’s frequency • Within groups: may favor the allele • Kin selection: direct genetic advantage; selection favors relatives

35. Social Systems • Society: a group of organisms of the same species that are organized in a cooperative manner • Advantages • Kin selection: greater odds of alleles surviving in the gene pool • Greater protection from predators • Increase feeding and mating success

36. Social Systems Flocking behavior decreases predation

37. Social Systems • Insect societies include individuals specialized for different tasks • Castes: groups of individuals that differ in size and morphology and perform different tasks • Workers and soldiers • Honeybees • Leaf-cutter ants • Fire ants