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Download ECOLOGY SPRING 2009 - Florida International University
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What do you understand by behavior? Learning Animal cognition Migratory behavior Ecology Reproduction 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 (instinct) or nurture (experience) 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 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 Artificial selection data has shown that behavioral differences among individuals often result from genetic differences Genetics of learning 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 in humans, 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 Classical conditioning: the paired presentation of two different kinds of stimuli with an association formed between them ◦ Ivan Pavlov: ◦ 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 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 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 Noble Price 1973 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 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 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 Migration involves population moving large distances: Monarch butterflies fly from North America to Mexico 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 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 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 Primate language: Vocabulary to communicate identity of specific predators 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 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 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 Nobel Price 1973shared with Lorenz Focus on: Development Physiological basis Function: including evolutionary significance 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 Optimal foraging assumes that: Behavior maximizes energy acquisition if the increased energy reserves lead to increases in reproductive success i.e. Avoid predators, Find mates Optimal behavior has evolved by natural 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 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 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 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
