Post on 28-Dec-2015
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
• 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
Approaches
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
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
Behavioral Genetics
• Artificial selection data has shown that behavioral differences among individuals often result from genetic differences
• Genetics of learning
• 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
Behavioral Genetics
• fosB present: mother cares for her young
• fosB absent: young are ignored and eventually die
Behavioral Genetics
• 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
Behavioral GeneticsVasopressin receptor
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
• 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
Learning
• 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
• 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
Learning
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
• 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
Development of Behavior
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
• 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
Orientation and Migratory Behavior
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
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
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
Communication
• 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
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
Behavioral Ecology
Optimal foraging makes two assumptions
1. 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
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
Behavioral Ecology
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
Advantage of male mate choice. Male Mormon
crickets choose heavier females as
mates, larger females have more eggs
Sexual Selection
• Male Mormon crickets use 30% of their body weight making up a spermatophore (nutritive protein containing packet) for the female
• 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
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
Sexual Selection
• 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
Altruism
• Kin selection: direct genetic advantage; selection favors relatives
• 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
Social Systems