Background and Early Studies

Behavioral Ecology

Chapter 55

Background and early studies

What is behavior?

•The way an animal responds to stimuli in its environment

•Behavior is a pattern of responses to a stimulus

How can we explain behavior?

•How it works physiologically

Proximate answer

•The adaptive value of the behavior

Ultimate answer

•So, behavioral scientists study what behavior an organism does, how it does it and why it does it.

Behavior

•Behavior is influenced by both genetic and environmental factors (behavior is an expression of genetic and environmental cues)

Nature versus nuture argument

Gene by environment interaction is important

Genes and behavior

•Almost all behavior has a genetic basis

•So, behavior is subject to evolution through natural selection!

•Behavior is essential to understanding an animal’s evolution and ecological interactions

History of behavioral ecology

•Konrad Lorenz--imprinting and instinct

•Karl von Frisch--honeybee dances & communication

•Niko Tinbergen--gull behavior and learning+instinct

•All three shared Nobel Prize in physiology/medicine in 1972

Konrad Lorenz

•Imprinting – learning that is limited to a specific time period in an animal’s life and that is generally irreversible

•Critical period (sensitive period)– a limited phase in an individual animal’s development when learning of particular behaviors can take place

Filial imprinting

Konrad Lorenz

•Wrote book “On Aggression” where he asserts that human aggressive impulses are to a degree innate, and draws analogies between human and animal territorial behavior

These assertions have engendered considerable controversy

Karl von Frisch

•Honeybees communicate:

Direction to food source

Distance to food source

Quality of food source

Two types of dances

•Round dance

•Waggle dance

Distance to food source

•The orientation of the straight run in the waggle dance conveys the direction of the food source, relative to the position of the sun

Distance to food source

•The duration or tempo of the straight runs conveys the distance between nest and target: Dance tempo slows down with increasing distance to the food source. The farther away the target, the longer the straight run part of the dance

Quality of food source

•The intensity of the dance conveys the quality of the food source

Robot bees

Tinbergen - gull feeding behavior

Gull feeding behavior

Learning

•This related experiment with artificial beaks shows learning by gull chicks

Tinbergen

•Published famous paper on the 4 questions in behavioral biology

Tinbergen’s four questions

1) Mechanisms

Genetic

Hormonal

Physiological

In grouse, males begin to exhibit mating behaviors when sex hormones rise

Tinbergen’s four questions

2) Development

Instincts

Learning

Instincts x learning

In grouse, females seem to learn mate choice from their mothers

Tinbergen’s four questions

3) Adaptiveness

Survival

Reproduction

Male grouse that attract the most females have higher reproductive success. However, display is costly to survival

Tinbergen’s four questions

4) Phylogenetic history

Development of behavior through ancestry

The grouse family generally shows this mate choice behavior, where males are elaborate

Development of behavior

Innate or instinctive behavior

•Performed without having been learned

•Usually triggered by simple sign stimuli

•Response to the stimulus is a stereotyped motor program (hard-wired)

Preset paths in nervous system

Innate behaviors

•Innate behaviors are developmentally fixed

•Not completely genetic, as a physical environment is necessary for the gene to be expressed

•The key to innate behaviors is that they are expressed under a wide variety of environmental conditions

Instinctive behavior

•Sign stimuli are often nonspecific

•Innate releasing mechanism - a neural component of the organism that provides the motor program

•Fixed action pattern – a sequence of behavioral acts that is essentially unchangeable and usually carried to completion once started

Instinctive behavior

•When a goose sees an egg outside the nest (sign stimulus), it begins a repeated movement of dragging the egg with its beak and neck

Stickleback

•Male stickleback fish will attack anything with a red underside

Supernormal stimuli

•Given a choice, animals respond to a larger stimuli than a smaller one

Supernormal stimuli

Behavior is genetic

Genetic basis of behavior

•In some cases, single genes control behavior

Adaptive behavior

•Behavior that promotes reproductive success

•Frequency of individuals expressing this behavior will be maintained or increase in successive generations due to natural selection

Learning influences behavior

•Animals alter their behavior as a result of previous experiences, which is learning

Feeding in gull hatchlings

Types of learning

•Nonassociative learning

Does not require an animal to form an association between 2 stimuli or between a stimulus and response

Habituation

•A type of nonassociative learning

•An individual learns NOT to respond to a stimulus that has neither good nor bad consequences

•Pigeons in cities learn that people are no threat and do not flee from them

•Deer become increasingly tame in parks

•Ability to ignore signals is adaptive

Types of learning

•Associative learning

Requires an association between 2 stimuli or between a stimulus and response

Behavior is “conditioned” through the association

Two major types:

Classical conditioning

Operant conditioning

Differ in the way associations are established

Classical conditioning

•Pair presentation of two different stimuli causes association between the two stimuli

•Also called Pavlovian conditioning

Operant conditioning

•A behavior becomes associated with its consequences

•“Trial-and-error” learning

What type of conditioning is this? What has the coyote learned?

Instinct and learning

•Innate predispositions toward forming certain associations

Pigeons can learn to associate food with colors, but not with sound

•Learning is possible only within the boundaries set by instinct

•In nature, adaptation by learning is important to survival

Spatial learning

•Through experience with an environment, an organism creates a mental map

•Birds remember the location of thousands of places where they have stored food

Animal Cognition

•Do animals other than humans possess cognition?

Cognition - the ability of an animal’s nervous system to perceive, store, process, and use information gathered by sensory receptors

In other words, do they process information in a way that suggests thinking?

Insight Learning

•An animal solves a problem without trial-and-error attempts at a solution

•Captive chimpanzees show insight learning when they solve a novel problem, as when they stack boxes to reach food that is out of reach

Instincts and learning

•Instinct = behavior exhibited without feedback from environment

•Learned behavior = behavior that can be altered in response to information acquired from environment

•Instinct and learning are not exclusive - they can interact!

Innate song

Bird Song: Instinct + Learning

•Bird comes hard-wired to listen for certain acoustical cues; instinctively pays attention to particular sounds

•Genetic template guides birds to learn the appropriate song

•Which dialect the bird sings depends on what song it hears

•Exposed to own species song during development

•Not exposed to song

New information shows that social interaction may override the genetic template!

Importance of social interactions