Ethology and Behavioral Ecology.

I. Terms and Concepts

Behavior: The response of an organism to signals from the environment.

Behaviors can be examined from a proximate (how) and an ultimate (why) perspective.

Are behaviors adaptive? Do they have a genetic basis?

Natural selection will favor behavioral traits that promote individual reproductive success as measured by the number of offspring that live to reproduce (the individual's personal fitness).

Ethology: the study of behaviors from the point of view of adaptation.

Instinct OR innate behavior: genetically programmed behavior that requires no learning.

Complex versions of this are known as fixed action patterns, which are typically triggered by some sign stimulus.

e.g. tail feathers in precopulatory position in male and female red-wing blackbirds.
e.g. death feign in hog-nosed snake (Photo below; See also figure 60.1 in Raven & Johnson).
hog-nosed snake.

Innate behaviors generally don't respond much to an animal's life experiences.

Learning: a change in behavior due to experience.

The ability to learn is closely related to the complexity of an animals nervous system.

Classical Conditioning - an association is formed between some normal body function and a stimulus, resulting in a reflex.

E.g. Pavlovian response in dogs.

Operant Conditioning - learning in which an animal is rewarded or punished for performing a behavior.

E.g. Rats in Skinner box   trial by error learning.

Imprinting - learning that occurs only during a critical period.

The process of imprinting is genetically determined, but the particular object to be imprinted on is learned. Mother-offspring imprinting is perhaps the most common. Based on work of Konrad Lorenz   1973 Nobel Prize in Medicine.

Habituation - learning that allows an animal to ignore repeated irrelevant stimuli.

II. Behavioral Ecology

Behavioral Ecology is the study of how animals interact with their environment, and the survival value of behaviors. Often focuses on the efficiency of a behavior and on its relative costs and benefits compared to other possible behaviors.

One the main premises of behavioral ecology is that all behaviors are assumed to have great survival value - otherwise the processes of natural selection (discussed a few lectures back) would have selected against it and removed it from the population.

A consequence of this assumption is that behavioral ecologists assume that behaviors are optimally adapted to at least some component of their environment. The challenge therefore is to find out what aspect of the environment is selecting against all other forms of this behavior other than what we find. (Remember that we discuss the actions of natural selection in double negatives, as in "not selected against".)

For example:

  1. Why do some animals live in groups while others do not (evolution of sociality)?
  2. Why do animals eat some types of food but not other types (optimal foraging strategies)?
  3. Why do some animals leave the region in which they were born (dispersal strategies)?
  4. Why do some animals act as helpers while others do not (kin selection and reciprocal altruism)?
Behavioral ecologists:
  • study how behavior serves as an adaptation and alters an animals reproductive success
  • study how natural selection shapes behavior
  • use a cost-benefit analysis of the behavior relative to alternate forms of the behavior (or of solving the problem) to determine the value of the behavior for natural selection
  • generate testable hypotheses
  • have dominated the field of animal behavior for the last 20+ years
  • These are "why" or ultimate questions, (as contrasted with the "how" or proximate questions) that we discussed last lecture) traceable to Niko Tinbergen, 1973 co-Nobel prize winner.

    e.g. Digger wasps and nest-locating behavior using a ring of pine cones and stones

    Proximate or Mechanistic question: How do they use their environment cues to locate their nest?

    Hypothesis or Answer: They use the arrangement and distribution of their cues, rather than the material of the cues themselves or the absolute location of the nest in space, to find their nest easier.

    Ultimate or Evolutionary question: Of what use is it to fitness if they use their environmental cues to locate their nest?

    Hypothesis or Answer: Helps to maximize the fitness of the wasp so that she can optimally use her time and energy to rear the maximum number of offspring

    Behavioral ecology often focuses on the efficiency of a behavior and on its relative costs and benefits compared to other possible behaviors.

    e.g. Optimal Foraging theory

    Why do some animals live in groups and others do not?

    To answer this, ask:

    How are cooperative and altruistic behaviors maintained within groups?

    1. Kin Selection and Inclusive Fitness (W.D. Hamilton).
    2. Reciprocal Altruism (R.D. Trivers).

    Why do male birds have inordinately developed plumage in many species?

    Sexual selection (Darwin)

    A Question For The Road: Can this field also apply to plants and other non-animals, or is this solely an animal focused field? Do plants have behavior? If so, can these actions be inherited?

    Updated March 22, 2005
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