Animal Behavior
Ref: Chapter 45
Behavior
Observable and coordinated responses to environmental stimuli
Ethology = scientific study of how animals behave Mechanistic questions: “how” a behavior
occurs by an animal’s structure Survival value questions: “why” a behavior
occurs and how it helps an animal to survive Evolutionary advantage = behavior increases
fitness
Genetic Basis to Behavior
Genetic Basis to Behavior:Nature vs. Nurture
Twin Studies Compare similarities between
Identical twins (share 100% DNA) Fraternal twins (share 50% DNA) Same environment (nurture)
Compare similarities for Identical twins reared apart Different environment; same genetics
(nature)
Genetic Basis to Behavior:Nature vs. Nurture
Twin Studies indicate differences in personality traits 50% polygenic inheritance 50% environmental influence
Development of Behavior Innate behavior
Fixed Action Pattern Response to
sign stimulus Sequence of unlearned
behaviors Always performed
same way Evolutionary advantage?
Development of Behavior
Learning Classical conditioning
Neutral stimulus paired with significant stimulus
Reflexive response triggered by neutral stimulus
EX: Pavlov’s dog (bell + food droolbell drool)
http://www.youtube.com/watch?v=WfZfMIHwSkU
Development of Behavior
Learning Operant conditioning
Gradual strengthening of stimulus-response connections
Stimulus Reward if proper response B F Skinner Evolutionary advantage?
Development of Behavior
Imprinting Learning occurs in
sensitive period Will follow first moving
object seen after hatching
Usually occurs in precocious young
Evolutionary advantage?
Development of Behavior
Learning Female chimpanzees termite fish like
mothers Learn by imitation Evolutionary
advantage?
Behavior is Adaptive
Behaviors that increase survival and reproductive success are passed down
Sexual selection = changes in males and females caused by mate choice and competition for mates
Sexual Dimorphism
Differences in appearance between genders
Male gorilla 1.5X size of female
Female Choice Female determines “best
mate”
Courtship rituals Birds
Male Competition
Dominance Dominant male mates with females Dominance determined by
confrontation
Male Competition
Territoriality Male defends his territory (and
harem) from other males
Male fur seals
Mockingbird
Chemical Communication
Pheromone: chemical signal passed between members of the same species
Tactile Communication
Waggle dance Grooming
Sociobiology
Principles of evolutionary biology applied to social behavior in animals
Benefits of living together must outweigh costs for society to persist
Advantages to Living Together
Avoid predators Raise young Find food
Disadvantages to Living Together
Competition over resources Potential low spot in hierarchy
Increased risk of disease and parasites
Altruism
Behavior that reduces direct fitness but increases indirect fitness
Inclusive fitness = reproductive success of self and relatives (who share your genes!)
Honeybee Society
Males - haploid (have 1 set of chromosomes)
Females – diploid (have 2 sets of chromosomes) Queen – reproductive Workers – sterile
Honeybee Genetics
Queen Passes half her chromosomes and all of
male’s chromosomes to offspring Queen shares half her chromosomes
with daughters Worker
Shares half of queen’s chromosomes and ALL of father’s chromosomes with sisters
Honeybee Genetics
Who is more closely related? Queen and female offspring Female offspring and female offspring
Is the queen exploiting the workers – or the workers exploiting the queen?
Helpers
Support reproducers
Later gain support for reproducing