1. Behavioral Biology Chapter 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. Approaches Innate behavior: instinctive, does not require learning
Preset paths in nervous system
Genetic: fixed action pattern
Example: goose replacing an egg from her nest

5. Approaches Egg retrieval behavior is triggered by a sign stimulus
Innate releasing mechanism or fixed action pattern is the stereotyped act
Not very specific: anything round will trigger the goose’s reaction
Once pattern begins, it goes to completion; even if the egg is removed

6. Approaches
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

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

8. Behavioral Genetics Human twin study
Identical twins: identical genetically
50 sets, twins raised separately
Similarity in personality, temperament, leisure time activities
Indicates that genetics plays a role in determining behavior even in humans

9. Behavioral Genetics Single gene: Drosophila
Alternative alleles for feeding behavior as larvae
One type moves around to eat
Second type remain in same area to eat
Courtship behavior also affected by a mutation in a single gene

10. 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

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

12. Behavioral Genetics Prairie voles are monogamous
Montane voles mate and do not work together to raise young
Different response to oxytocin and vasopressin
Peptide receptors different

13. 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

14. 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

15. Learning
Associative learning is involved in predator-prey interactions: after being stung the toad learns not to eat bumblebees.

16. 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

17. 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

18. Learning Instinct and learning
Innate predispositions toward forming certain associations
Pigeons can learn to associate food with colors, but not with sound
Learning is possible only within the boundaries set by instinct
In nature, adaptation by learning is important to survival

19. Learning
Clark’s nutcracker can remember the locations of up to 2000 seed caches months after hiding them
Uses spatial memory

20. 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

21. Development of Behavior
Goslings follow Konrad Lorenz as if he were their mother
1973 Nobel Prize

22. 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

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

24. Development of Behavior
Cuckoos are raised by a different species
Learn their own song: innate

25. Animal Cognition Do animals show cognitive behavior
What type of behavior demonstrates cognition?
Japanese macaques learned to wash sand off potatoes
Chimps pull the leaves of off a tree branch to use it as a tool for picking termites
Some birds learn to take off milk caps from bottles

26. Animal Cognition

27. 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

28. Orientation and Migratory Behavior
Migration involves population moving large distances
Monarch butterflies fly from North America to Mexico

29. Orientation and Migratory Behavior
It takes generations for the migration

30. Orientation and Migratory Behavior
Bobolinks have changed their migration by adding a new segment

31. 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

32. Orientation and Migratory Behavior
Migratory behavior of starlings

33. 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

35. 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

36. Communication
Bioluminescent displays of lampyrid beetles are species-specific. Each number represents the flash pattern of a male of a different species

37. Communication facilitates group living
Guards: set off an alarm call so group can seek shelter
Social insects produce pheromones that trigger attack behavior
Ants deposit trail pheromones between nest and food source

38. The waggle dance of honeybees
Communication
The waggle dance of honeybees

39. Communication
James L. Gould devised an experiment to trick hive members into going in the wrong direction
Supported von Frisch’s explanation of the bees using the Sun as their reference position
Eliminated Wenner’s challenge that it was flower odor that drew the bees to the food location
Robot bees are now being used

40. Communication Primate language:
Vocabulary to communicate identity of specific predators

41. 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

42. Communication Signals vary in their degree of specificity
Level of specificity: relates to the function of a signal
Mark territories with pheromones
Species and other species specific
Pursuit-deterrent signals: predator has been seen and should not waste time chasing the prey

43. Communication
Cleaner Fish. The grouper has entered the cleaner fish’s “station” and adopted a posture that allows the cleaner fish to enter the mouth and gills and feed on attached parasites

44. Behavioral Ecology
Niko Tinbergen divided the investigation of behavior into the study of
Development
Physiological basis
Function: including evolutionary significance

45. Behavioral Ecology Evolutionary analysis: survival value of behavior
Tinbergen observed gull nestlings hatch and parents remove the shells of the eggs
Placed broken eggs by the nests
Predators (crows) found nests with broken eggs and ate the hatchlings
Nests without egg shells had less predation

46. 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

47. 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

48. Optimal foraging makes two assumptions
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

49. Behavioral Ecology Optimal behavior has evolved by natural selection
Female zebra finches that were successful foraging had successful offspring
Removed offspring to ensure learning not a part of the foraging success

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

51. 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

52. Behavioral Ecology
Competition for space. Territory size in birds is adjusted according to the number of competitors

53. Behavioral Ecology
The benefit of territoriality. Sunbirds and hummingbirds protect their food source by attacking others that approach flowers in their territory

54. Behavioral Ecology
In some species, exclusive access to females is a more important determinant of territory size for males than food
Several females in territory are defended vigorously
Nonbreeding season
Male territory size decreases
Aggression decreases

55. 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

56. Sexual Selection Sexes often have different reproductive strategies
Females do not mate with the first male they encounter
Mate choice: evaluate a male’s quality
Peahens mate with males with more eyespots in their tail
Frogs mate with males that have complex calls

57. Sexual Selection
Products of sexual selection. Attracting mates with long feathers is common in bird species

58. Sexual Selection
Males engage in mate choice less frequently than females
Parental investment: contributions each sex makes in producing and rearing offspring
Females have higher investment
Eggs larger than sperm
Females are usually responsible for gestation and lactation, or yolk production

59. Sexual Selection
Consequences of disparities in reproductive investment - sexes face different selective pressures
Male fitness rarely limited by sperm count
Number of eggs produced often does limit reproductive success
Females are choosey because it is costly for them to reproduce

60. Sexual Selection
Advantage of male mate choice. Male Mormon crickets choose heavier females as mates, larger females have more eggs

61. Sexual Selection
Male Mormon crickets use 30% of their body weight making up a spermatophore for the female
Male seahorses brood and care for the young
Females compete for males when males are choosey

62. Sexual Selection Sexual selection involves both:
Intrasexual selection: interactions between members of one sex
Intersexual selection: interactions between members of opposite sex (mate choice)
Sexual selection leads to the evolution of structures used in combat with other males. Ex. Antlers, horns

63. Sexual Selection
Secondary sexual characteristics: horns, long feathers, coloration

64. Sexual Selection Intrasexual selection
Males compete for opportunity to mate
Males defend their territory & females
Dominant males mate with many females: polygyny
Sexual dimorphism: males look different from the females

65. Sexual Selection Sperm competition Females mate with multiple males
Males evolved features to maximize sperm success
Testes large to produce many sperm per mating
Sperm large and swim more rapidly

66. Sexual Selection Intersexual selection Direct benefits of mate choice
Females benefit by choosing males that help raise offspring
Males that do not help raise young; provide territories, nesting sites, food, predator refuges

67. Sexual Selection Indirect benefits of mate choice
Choose male that is healthiest or oldest
Guppies and birds: coloration reflects quality of diet and health
Less likely to carry disease
Good genes
Handicap hypothesis: genetically superior mates can survive a handicap

68. Sexual Selection Alternative Theory
Sensory exploitation: evolution in males of an attractive signal that “exploits” sound or colors
Túngara frog
Cluck sound

69. Sexual Selection
Mating systems reflect adaptations for reproductive success
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

70. 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

71. Sexual Selection
The study of paternity. a) DNA fingerprinting gel, b) results of DNA fingerprinting study in red-winged blackbirds

72. Sexual Selection Extra-pair copulations (EPCs)
Red-winged blackbirds study
Half of all nests contained at least one hatchling fertilized b a male not defending the territory
Evolutionary advantage of EPCs:
Males: increased reproductive success
Females: genetically superior individual mated with, even if paired with another male

73. Sexual Selection Alternative mating strategies Fish
Two genetic classes of males
Large and small
External fertilization: small males “sneak” in to fertilize females
Dung beetles
Territorial males have large horns
Small males do not have horns or territories, intercept females in tunnels

74. Male fish fertilizing a female’s eggs
Sexual Selection
Male fish fertilizing a female’s eggs

75. 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

76. Altruism
Reciprocal altruism: Partnerships in which mutual exchanges of altruistic acts occur because they benefit both participants
Cheaters are discriminated against
Vampire bats
Share blood
meal

77. Altruism
Kin selection: direct genetic advantage; selection favors relatives
William Hamilton: explanation in 1964
Brothers: 50% of alleles
First cousin: 1/8th of alleles
Hamiltons’s rule: altruistic acts are favored when rb > c
b and c are benefits and costs, r is the coefficient of relatedness

78. Altruism

79. Altruism
Kin selection in white-fronted bee-eater

80. Altruism Haplodiploidy and Hymenopteran social evolution
Bee hive: eusocial society
single queen lays eggs
50,000 workers, no eggs
Cooperative care of the brood: workers propagate more of their own alleles by giving up their own reproduction to assist their mother in rearing their sisters (75%)

81. Reproductive division of labor in honeybees
Altruism
Reproductive division of labor in honeybees
Female workers share 75% of alleles with each sister
Males are haploid
Queen shares 50% of alleles with offspring

82. 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

83. Flocking behavior decreases predation
Social Systems
Flocking behavior decreases predation

84. 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

85. Social Systems Foraging and predator avoidance
Meerkat sentinel on duty
Take turns to act as lookout