Session 3: Behavior

1.  Key Concepts:

Understanding behavior of wildlife is the key to understanding everything.  Behavior includes the active and inactive states and represents the sum of the interactions an organism has with its world.

2.  Definitions & Terms:

Behavior

The active and inactive components that comprise an animal's life, including feeding, mating, and resting behaviors as well as the more subtle interactions that it has with its cohorts, community, and environment.

Phenotype

The physical or functional characteristics of an organism, produced by the interaction of genotype and environment during growth and development.

Genotype

The genetic profile of an individual.

Hypothesis

A testable explanation of an observed phenomenon.

Exaptation

The evolutionary co-opting of an existing trait for a new function

3.  What is behavior?

In primate behavior, understanding the inaction is as important as understanding the action.  Due to the complexity of social structure in primate groups, behavior determines hierarchy, access to resources, access to mates, and more.

What exhibits behavior?

Evolution exerts pressure on the phenotype which is constructed by the interaction of the organism with its environment, the genetic makeup, development and phylogenetic history of the organism.

What causes behavior?

According to Tinbergen, there are two separate causes of behavior:

1. The Proximal Cause - immediate environmental stimulus
2. The Ontogenetic Cause - the life history stimulus, or changes over developmental time

The ultimate cause of behavior is the suite of selective pressures that would have favored individuals with the genetic material that the current population begins life with.

4.  The evolution of behavior:

One action can have several different causes.  Using his original model of causation of behavior (above), Tinbergen then expanded his focus to tease apart the  four narrow, causative answers to behavior.  For one action, each of these four provides an explanation of the reason for the behavior.

1. Proximal Cause:  the immediate stimulus or the time just before event
2. Ontogenetic Cause: the cause has developed between conception and moment of stimulus
3. Evolutionary Cause: the phylogenetic cause, the reaction to stimulus reflects when selection favored genetically similar ancestors
4. Functional Cause: the reaction to stimulus reflects future consequences of behavior

The adaptive significance of behavior reflects our current understanding of that behavior.  However, not all behavior is adaptive because the function of the behavior today may not be the same as in the context when it was favored by selection in the past, or exaptation.  It is important to remember that selection is not instantaneous or based on single events and that selection operates on average or usual outcomes.

In describing the evolution of behaviors, there is a danger of “thinking backwards” evolutionarily.  This can lead to errors by reaffirming the consequence or finding evidence that traits were “evolved for” specific tasks.

5.  How do you measure behavior?

Considerations:

Key variables exist in assessing the function of a behavior.  These include:

• Exaptation - the co-opting of "old" traits for a novel function
• Preadaptation - a trait switches functions
• Non-functional behavior
• Ontogenetic shifts in behavior—learning
• Plasticity in response—slight variations in behavior among individuals

Behavioral expression is limited by the expression of the genotype/phenotype.  This limits the range of potential behaviors available to the organism, and to fully understand the behavior it should be assessed across a range of groups, populations, and species.  Evolutionarily, behaviors are constrained to acting to what is “good enough.”  Evolution does not select for the best, but instead the most adequate, in all traits including behavioral traits.  Evolutionary stable strategies (ESS) of behavior develop when not participating in a behavior becomes deleterious to the individual.  Maladaptive behaviors can remain in a population through linkage with other traits, the lack of fine-tuning of natural selection, or through a possibility of multiple patterns/ranges of expression in a behavioral suite.

Observational Methods for the Study of Behavior: In the beginning there is the question. It all begins with the question.

If behavior is all the action and inaction performed by an individual, our record of that behavior is the perceived and written record of those actions and inactions.  Our record is bound by our ability to perceive their interactions, and ultimately this limits our ability to understand behavior.  Especially with primates, be wary of anthropomorphism and anthropocentrism.

Keep in mind that “these primates are not little humans, and that even if the action does reflect the same emotion, motive, or intention as a human would express under the same circumstances, the observer cannot prove it” (Patterson 2001).

Data collection methods: Careful methodology can help overcome our own bias.

Different types of methods can be utilized to collect different types of data.  Not all data types are equal or appropriate for answering all questions.  For example, duration data and event data are different types of data and so must be treated as such.

• Focal animal—continuous sampling
• Group scan—interval sampling
• All occurrence—focuses on one or two specific behaviors
• Continuous—record everything
• Timed Scan—especially good for "slice"
• Ad libitum notes—really important to note things; can aid other data collection methods by qualifying scenarios and providing context for interactions

Sample Data Collection Sheet: 

The Design, or How to build a project:

1. Identify the question and pose hypotheses.
2. Identify the data needed to answer the question and/or address the hypotheses.  It is also important, here, to consider appropriate analysis.
3. Identify the format for presentation and dissemination of your results.

6.  Additional Material:

Required Reading:

Primates in Perspective.  2007.  eds.  C. J. Campbell, A. Fuentes, K.C. MacKinnon, M. Panger, and S. K. Bearder. Oxford University Press.

Chapter 28:  The New Era of Primate Socioecology.  Overdorff and Parga.