Post on 23-Dec-2015
Behavioral Ecology
Chapter 37
Nature vs. Nurture
Behavior To what degree do our
genes (nature) and environmental influences (nurture) affect behavior?
Nature versus Nurture: Genetic Influences
Lovebird Nesting Behavior Genetic role in nest
making: Fischer lovebirds,
Agapornis fischeri Peach-face
lovebirds, Agapornis roseicollis
Hybrid lovebirds exhibit intermediate behavior
Nature versus Nurture: Genetic Influences
Garter Snake Experiments Genetic role in food
preference In the wild:
Inland populations of garter snakes are aquatic
Coastal populations are terrestrial
In the laboratory: Inland snakes refused
slugs Coastal snakes readily
accepted them Hybrid snakes exhibited
intermediate acceptance of slugs as food
Nature versus Nurture: Genetic Influences
Garter Snake Experiments Sensory receptors are
specific for prey Presented baby snakes
with slug extract on cotton swabs
Coastal Inland
Genetic difference – physiological difference
Nature versus Nurture: Genetic Influences
Experiments with Humans Twin Studies
Look at characteristics of twins raised apart
Many share common preferences in food, activity patterns, and mate selection
Nature versus Nurture: Environmental Influences Fixed Action Patterns (FAP)
Specific behaviors elicited by a sign stimulus
Learning A durable change in
behavior brought about by experience
Nature versus Nurture: Environmental Influences
Learning in Birds Imprinting: a simple
form of learning Sensitive period Social interactions
between parent and offspring during the sensitive period are important
Nature versus Nurture: Environmental Influences
Learning in Birds Song Learning
White-crowned sparrows Species-specific song with different dialects
Three groups: Birds that heard no songs
Sang an undeveloped song as adults Birds that heard White-crowned sparrows
Sang in that dialect as long as tape was played during a sensitive period
Birds that had adult tutor Sang the tutor’s song even if a different species
and no matter when tutoring began
Nature versus Nurture: Environmental Influences
Associative learning 1. Classical Conditioning
The presentation of two different types of stimuli at the same time
Causes an animal to form an association between them
2. Operant Conditioning A stimulus-response
connection is strengthened Training an animal by
rewarding it
Other means of learning….
Animals may learn through insight, imitation, and habituation Insight learning
An animal suddenly solves a problem without any prior experience with the problem
Habituation An animal no longer
responds to a repeated stimulus
Mating Behaviors
Sexual Selection Adaptive changes that increase ability to
attract a mate Influences fitness
Three influences on mating: Female Choice Male Competition Human Mating
1. Female Choice
Two Hypotheses: Good Genes Hypothesis
Females choose mates on basis of traits that improve survival
Run-away Hypothesis Females choose mates on
basis of traits that improve appearance
2. Male Competition
Males can produce many offspring because continuously produce sperm in large numbers Less time and energy invested in reproduction Males compete to inseminate as many
females as possible Cost-benefit analyses
Is the benefit of access to mating worth the cost of competition among males??
2. Male Competition
Males and females have separate dominance hierarchies Higher-ranking animal
has greater access to resources than a lower-ranking animal
Dominance is decided by confrontations
3. Mating in Humans
Human Males Compete Humans are dimorphic
Men are larger and stronger likely as result of past selection by females
Males pay a price - the average life span is seven years less than females!
Sociobiology
Applies the principles of evolutionary biology to the study of social behavior in animals
Hypothesis Living in a society has a greater reproductive benefit
than reproductive cost Benefits of Group Living
Helps an animal avoid predators, rear offspring, and find food
Disadvantages to Group Living Competition among members of the group for
resources Exposes group members to illnesses and parasites
Sociobiology
Helpers at the Nest Minimal short-term
reproductive sacrifice made to maximize future reproductive potential
Helper contributes to survival of kin
Sociobiology and Human Culture
Humans live in organized societies Culture of a human society involves a wide
spectrum of customs Earliest organized societies may have been
the “hunters-gatherers” Predatory lifestyle likely encouraged the
evolution of intelligence and the development of language
Animal Communication
Communication 4 types communication signals:
Chemical Auditory Visual Tactile
Animal Communication
Chemical Communication Pheromones
Powerful chemical signals passed in low concentration
May be released into the air or used in territory marking
Animal Communication
Auditory Communication Very rapid and can be
modified for specific situations
Animal Communication
Visual Communication Most used by diurnal
species-must be able to be seen
Plumage, courtship “dances”, aggressive displays, etc
Animal Communication
Tactile Communication Occurs when one
individual touches another