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