Our ultimate goal is to understand the expression of particular behaviors under specific conditions.

First, examine some of the underlying assumptions about the mechanisms that produce behaviors

1) Behaviors are the product of natural selection; thus, a genetic component to their expression must exist

2) Genes don't make behaviors, they make "survival machines" that behave

These assumptions lead to the conclusion that: All behaviors are the result of both genetic and environmental factors

1) Behaviors are the product of natural selection; thus, a genetic component to their expression must exist

Lines of evidence that genes are important:

a) Purebred stains (from inbreeding)

Do they behave the same way in the same environment?

Do different genotypes raised in the same environment express different behaviors?

Mice

b) The behavior of hybrids

Do hybrids show behaviors intermediate to that of parental types?

Lovebirds

c) The behavior of close relatives

Some animal breeding programs rely on inheritance of behaviors (e.g., tameness, aggressiveness, etc.)

What about humans?

Do offspring show certain behaviors that are also expressed by one parent?

Schizophrenics

What about identical twins?

These lines of evidence indicate there is a link, but give no suggestion of how it is manifested.

 

Could it be a single gene?

 

Single gene effects in the form of mutations

Drosophila

Honeybees

By themselves, bees could be the subject of an entire course. For examples:

Behavioral Genetics

Neurobiology

2) Genes don't make behaviors, they make "survival machines" that behave:

Genes do not make traits. They simply contain the code for protein construction.

 

The products needed to produce these proteins (amino acids) ultimately come from the environment.

Thus, at its most basic: Genotype + environment = proteins

Many of these proteins are enzymes that regulate the biochemical reactions within a developing organism

 

Genes also control cell metabolism, and thus, the production of new cells

 

The complex interplay of gene expression for specific proteins, molecule utilization (from the environment) and cell division is extremely organized.

The right cells develop at the right place and the right time

This allows differentiation during development, leading to different cell complexes that are interconnected (e.g., muscles, nerves, glands, plus supporting systems such as circulation, digestion, etc.)

 

This complex system of specialized cells are what allow behaviors

To behave adaptively, an animal should be able to:

1) Detect environmental conditions (both physical and biological) that influence fitness.

2) Process information about the environment and have a "program" for responding.

3) Perform appropriate behaviors, as dictated by the "program"

4) Do all of these things quickly.

Under natural conditions, all animals, even single-celled, generally do all four of these things extremely well.

How?  You need some type of nervous system for detecting and transmitting information.

Receptor cells detect external energy: radiant, chemical, mechanical, or electrical

Being terrestrial, vertebrate, chauvinists, we generally characterize these environmental stimuli as: sight, taste, smell, sound, touch (the "five senses")

 

Top

Take me to the previous lecture

Take me to the next lecture

Take me to the course Moodle page