behavior

WHAT IS BEHAVIOR?

  • A behavior is any action performed by an animal.
  • Understanding behaviors requires studying the entire life history and ecology of an organism.
  • There is a debate on the influence of nature vs. nurture:
    • Many behaviors are influenced by genes (nature).
    • Genes regulate:
    • Brain development
    • Hormonal mechanisms
    • Innate behaviors (instincts)
    • The environment (nurture) also influences behavior, but the extent is debated.

THE GENETIC BASIS FOR BEHAVIOR

  • Classic experiments demonstrate how genes influence behavior:
    • Species hybrid studies (e.g., lovebirds).
    • Physiological studies (e.g., garter snakes).
    • Twin studies in humans.

NEST BUILDING IN LOVEBIRDS

  • Different species exhibit distinct nest construction behaviors:
    • Fischer lovebirds carry larger nesting materials in their bills.
    • Peach-face lovebirds tuck smaller materials between their feathers.
    • Both species are closely related.
  • Hypothesis: If behavioral differences are genetic, hybrids should show intermediate behaviors for nesting.

NEST BUILDING IN LOVEBIRD HYBRIDS

  • Peach-face x Fischer hybrids were bred:
    • Used bills to cut nesting materials into medium lengths.
    • Tucked these mediums into feathers, which often fell out.
    • Eventually, hybrids learned to carry materials using their bills after ~3 years of attempts.
    • Maintained the instinct to tuck materials into their feathers initially.

FOOD CHOICE IN GARTER SNAKES

  • Two California garter snake species:
    • Inland populations feed underwater on frogs/fish.
    • Coastal populations primarily eat slugs.
  • Laboratory findings:
    • Inland snakes reject slugs; coastal snakes accept them.
    • Hybrid snakes showed a preference for slugs.

FOOD CHOICE IN GARTER SNAKES (continued)

  • Experiments suggest a physiological basis for food choices:
    • Snakes use tongue flicks to detect smells and identify prey.
    • Inland snakes utilize fewer tongue flicks on slug extracts, indicating a lower interest.
    • Links taste preference genetically.

TWIN STUDIES IN HUMANS

  • Studies of twins separated at birth compared to those raised together:
    • Twins raised apart often show similarities similar to those raised together.
    • Suggests genes significantly shape personality and social attitudes.
    • Even select mates with similar traits.

NURTURING BEHAVIOR IN MICE

  • Maternal behavior in mice is influenced by the fosB gene:
    • Sensory receptor messages activate fosB alleles during mother-baby interactions.
    • Initiates hormonal changes leading to maternal behaviors:
    • Cleaning, nursing, nesting, warming.

NURTURING BEHAVIOR IN MICE (continued)

  • Mice lacking nurturing behaviors had non-functional fosB alleles:
    • Their hypothalamus failed to produce effects or hormones related to maternal care.
  • The significance of fosB alleles on natural selection.

NATURAL SELECTION AND BEHAVIOR

  • Family interactions often center around questions about one's life choices.
  • Parents are inclined to foster behaviors that might lead to grandchildren.

INSTINCT

  • Instinct is an innate behavior not learned from experience:
    • Typically programmed behaviors from birth.
    • Responses are generally uniform across a species and require no learning.

ENVIRONMENT & INNATE BEHAVIOR

  • Environmental influences on instinctual behaviors:
    • Hormone levels alter behaviors during:
    • Hibernation, migration, mating, sleep/activity.
    • Stimuli like precipitation, temperature, day length, food availability play a role.

ENVIRONMENT AND INNATE BEHAVIOR (continued)

  • Fixed-Action Patterns are sequences of behaviors triggered by environmental stimuli, proceeding to completion without deviation:
    • Example: Male stickleback fish show aggression towards red.

FIXED ACTION PATTERNS

  • Patterns traditionally deemed fixed can often be modified:
    • Habituation as a change in behavior through repeated exposure to stimuli.
    • Example: Predator avoidance behavior improves with experience.

MIGRATORY BEHAVIOR

  • Migration is defined as long-distance travel:
    • Often occurs between breeding and overwintering areas:
    • E.g., Loggerhead turtles migrate from Florida to the Mediterranean, returning to lay eggs on their original beaches.

STARLING STUDY

  • Starlings migrate east to west:
    • Scientists found that inexperienced starlings continue flying west even after being relocated.
    • Demonstrates orientation (inexperienced) versus navigation (experienced).

ENVIRONMENT & LEARNED BEHAVIOR

  • Environmental impacts on learned behaviors:
    • Learned behaviors vary between individuals of the same species:
    • Influenced by life experiences.
  • Three primary ways animals learn:
    • Conditioning (repeated experiences).
    • Observation (watching others).
    • Insight (problem solving).

RAVEN FEEDING STUDY

  • Ravens learn to retrieve food using previously unfamiliar tools:
    • First raven mastered the method, others imitate quickly after observing.

TOOLS & PLANNING BEHAVIORS

  • Animals demonstrate planning abilities:
    • Sea otters save tools (rocks) to open clams.
    • Chimpanzees create tools from twigs to fish for termites.

ANIMAL EMOTIONS

  • Although behaviorists typically neglect animal emotions, some researchers posit similarities between humans and animals due to evolutionary ties:
    • Pets exhibit joy when reunited with owners.
    • Mothers may express anxiety when separated from their young.

BEHAVIORS THAT INCREASE FITNESS

  • Behavioral ecology studies how natural selection influences behavior:
    • Fitness is the relative reproductive success of an individual compared to peers.
    • Behaviors that enhance survival and reproduction become more common through natural selection.
    • Adaptive behaviors enhance fitness; examples include territoriality, reproductive behaviors, social behaviors, and altruism.

TERRITORIALITY

  • Territory is a defended home range:
    • Territorial behaviors protect exclusive access to resources.
    • Territoriality is notable during breeding.

TERRITORIALITY STRATEGIES

  • Hawk vs. Dove strategy in territorial disputes:
    • Hawk Strategy involves aggression, retreating if injured.
    • Dove Strategy intimidates opponents, used to avoid direct conflict.

REPRODUCTIVE BEHAVIORS

  • Reproductive behaviors aim to maximize adult descendants:
    • Males and females exert energy differently:
    • Females invest in offspring care and survival.
    • Males compete for mating opportunities.

MALE AND FEMALE DIFFERENCES

  • Sexual dimorphism arises from natural selection:
    • Females are limited by egg production, while males are not limited in sperm.

SOCIAL BEHAVIORS

  • Social behaviors enhance group fitness:
    • Living in groups provides benefits such as predator avoidance and cooperative care of young.
    • Downsides include disease risk and hierarchy constraints.

SOCIETY AND ALTRUISTIC BEHAVIORS

  • Altruism involves sacrifices by individuals for the benefit of others:
    • True altruism is absent in nature; behaviors benefit the individual's relatives or the individual themselves (kin selection).

RECIPROCAL ALTRUISM

  • Altruistic behaviors benefiting the individual can occur among unrelated individuals:
    • Example: tropical vampire bats share meals, ensuring mutual benefit in the future.
    • Cheating is discouraged and can lead to exclusion from benefits.