The quest of Behavioral Ecology: why do animals behave as they do?

To understand behavioral ecology, we must understand the link between the expression of behaviors and individual fitness.

Remember the big three: Food, Sex, and Death

 

Let's start with an example: scrub jays in North America

California Scrub-Jays and Florida Scrub-Jays. (California Scrub-Jays and Woodhouse's Scrub-Jays were recently split as two species from the Western Scrub-Jay)

There is also the Island Scrub-Jay, found only on the Channel Islands off of the California coast. They offer insights into evolutionary processes and sympatric speciation

California Scrub-Jays have a wide geographic range, while Florida Scrub-Jays have an extremely limited range

Very different social organizations: in our area, monogomous pairs of California Scrub-Jays defend territories with "floaters" and seasonal mixing of groups. In Florida there is much more cooperation: "helpers and the nest" with permanent territories and cooperative breeding in family groups (Island Scrub-Jays are even more strictly monogamous that their west-coast counterparts).

Making sense of these differences involves a strong understanding of ecological factors and related costs and benefits accruing to individuals... studies of this type are the core of Behavioral Ecology.

 

 

Specific topics we will explore:

Behaviors that influence dispersion: grouping vs spread out

The evolution of anisogamy and sex, and the associated conflicts of interests that lead to sex-specific patterns of behaviors

The expression of life history traits (e.g., the timing and intensity of reproduction) and how these influence the behaviors of individuals at different times of life

The expression of parental care

The evolution of mating systems

The expression of "alternative" mating tactics (sneaky males, sex-change, hermaphrodites, etc.)

The expression of "altruistic" or cooperative behaviors in a "selfish" world

 

Diversity in behavior can be examined as a function of animal Social Organization (where animals are found and who interacts with whom)

Primary Social Organization: Behaviors that relate directly to temporal and spatial patterns of distribution (grouping, spreading out, etc.)

 

Higher-order Social Organization: Behaviors that relate to social interactions among animals (mating systems, parental care, cooperation, etc.)

 

Why treat dispersion separately from social behavior issues? After all, most patterns of dispersion involve some level of social interaction?

Patterns of dispersion (the frequency and consistency of encounters between individuals) establish the "template" for social interactions.... selection for "higher order" social behaviors.

 

Why is math important to the study of animal behavior?

Mathematical methods demand explicit formulations (in contrast to the vagueness of many verbal arguments

 

Models are useful for developing general concepts that may apply to many different types of organism

 

Models may suggest non-intuitive relationships

 

Caveats:

Models often rely on overly simple assumptions,

Testing models can be problematic (are the data lacking or is the model wrong?)

Hypotheses generated by models may be neither exclusive, nor exhaustive

 

Still, mathematical treatments of animal behavior can be very useful IF you understand the method behind the madness

Three basic sources of theory in behavioral ecology:

Comparative methods

Optimality theory

Game theory

Comparative methods can be useful for identifying generally important aspects of behavior, but theory is often post hoc.

Overview of quantitative theoretical approaches to the study of animal behavior

Both optimality and game theory seek to answer the same question: given a particular ecological scenario (physical and social environmental conditions) for a given individual, should it continue a set of behaviors or adopt some alternative?

Definitions:

Strategies: the options available to an animal (no decision making implied!)

Alternative strategies can either be discrete or continuous.

 

Payoffs: the net effect on fitness associated with a specific strategy (assumes strategies have both costs and benefits)

 

Many variables may influence fitness, though only a subset may be relevant to the model.

 

Thus, choice of a "currency" that relates to fitness is important

 

Overall Lifetime Inclusive Fitness (OLIF) is the only complete currency

It is virtually impossible to measure

 

Proxies for OLIF usually relate to one of the big three (food, sex, or death)

 

Choosing a modeling approach

Optimality models are useful when we focus on a single individual in a contest against NATURE (all environmental variable lumped together)

Such an approach works if none of the components that make up NATURE respond to an animal's strategy (i.e. they don't change their behavior or relationship towards the focal animal and its behavior)

If NATURE responds, theorists often turn to Game Theory