BIOMED SCIE LECTURE 21 Behaviour

• A behavior is the nervous system’s response to a stimulus and is carried out by the muscular or the hormonal system . Behavior is subject to natural selection
• Behavioral ecology is the study of the ecological and evolutionary basis for animal behavior


  • In behavioral ecology, a signal is a behavior that causes a change in another animal’s behavior . Communication is the transmission and reception of signals
• Animals communicate using visual, chemical, tactile, and auditory signals


  Fruit fly courtship follows a three step stimulus- response chain
• Pheromones


  Many animals that communicate through odors emit chemical substances called pheromones
• Innate behavior is developmentally fixed and does not vary among individuals
• Cross-fostering studies help behavioral ecologists to identify the contribution of environment to an animal’s behavior
• A cross-fostering study places the young from one species in the care of adults from another species
• Cross-fostered mice developed some behaviors that were consistent with their foster parents
• In humans, twin studies allow researchers to compare the relative influences of genetics and environment on behavior
• Learning is the modification of behavior based on specific experience
• Imprinting is a behavior that includes learning and innate components and is generally irreversible . It is distinguished from other learning by a sensitive period . A sensitive period is a limited developmental phase that is the only time when certain behaviors can be learned
• In associative learning, animals associate one feature of their environment with another– For example, a white-footed mouse will avoid eating caterpillars with specific colors after a bad experience with a distasteful monarch butterfly caterpillar
• Classical conditioning is a type of associative learning in which an arbitrary stimulus is associated with a reward or punishment– For example, a dog that repeatedly hears a bell before being fed will salivate in anticipation at the bell’s sound
• Operant conditioning is a type of associative learning in which an animal learns to associate one of its behaviors with a reward or punishment
• It is also called trial-and-error learning– For example, a rat that is fed after pushing a lever will learn to push the lever in order to receive food– For example, a predator may learn to avoid a specific type of prey associated with a painful experience
• Social learning is learning through the observation of others and forms the roots of culture– For example, young chimpanzees learn to crack palm nuts with stones by copying older chimpanzees– For example, vervet monkeys give and respond to distinct alarm calls for different predators
• Behavior enhances survival and reproductive success in a population
• Mating behavior includes seeking or attracting mates, choosing among potential mates, competing for mates, and caring for offspring• Mating relationships define a number of distinct mating systems
• Like rock-paper-scissors, each strategy will outcompete one strategy but be outcompeted by the other strategy• The success of each strategy depends on the frequency of all of the strategies; this drives frequency-dependent selection
• Animal behavior is governed by complex interactions between genetic and environmental factors• Selfless behavior can be explained by inclusive fitness
• A master regulatory gene can control many behaviors– For example, a single gene controls many behaviors of the male fruit fly courtship ritual• Multiple independent genes can contribute to a single behavior
• When behavioral variation within a species corresponds to environmental variation, it may be evidence of past evolution
• Natural selection favors behavior that maximizes an individual’s survival and reproduction• These behaviors are often selfish• On occasion, some animals behave in ways that reduce their individual fitness but increase the fitness of others• This kind of behavior is called altruism, or selflessness
• under threat from a predator, an individual Belding’s ground squirrel will make an alarm call to warn others, even though calling increases the chances that the caller is killed
• in naked mole rat populations, nonreproductive individuals may sacrifice their lives protecting their reproductive queen and kings from predators
• Altruistic behavior toward unrelated individuals can be adaptive if the aided individual returns the favor in the future• This type of altruism is called reciprocal altruism
• Reciprocal altruism is limited to species with stable social groups where individuals meet repeatedly, and cheaters (who don’t reciprocate) are punished• Reciprocal altruism has been used to explain altruism between unrelated individuals in humans
• No other species comes close to matching the social learning and cultural transmission that occur among humans• Human culture is related to evolutionary theory in the distinct discipline of sociobiology• Human behavior, like that of other species, results from interaction between genes and environment
• • Behaviour has evolved II. Evolution, ultimately, is a change in gene frequencies III. Thus, are there genes for behaviour? Where the ‘behaviour’ is the ‘phenotype’. and where the genes for that particular behaviour are the ‘genotype’.IV. Use of molecular genetics techniques by behavioural researchers
• Natural Selection acts on the phenotype, but is dependent upon the genotype• Behaviour of an individual is a phenotype(if we think in purely genetic terms)
• Behaviour that occurs without obvious environmental influence= innate behaviour
• Development involves continual interaction between genes and environment. Each phase sets the stage for the next – epigenesis
• Juvenile animals often have characteristic “innate” behaviours that are lost in adulthood
• • Innate behaviours occur without obvious environmental influence (genetic control)