- Animal Behavior

BACKGROUND: Animal behavior, for the most part, consists of motor actions in response to sensory stimuli, such as light, sound, touch, chemical, etc. The motor response to these stimuli may depend on the seasonal physiological condition of the animal. For example a male lizard will respond with courtship behavior upon seeing a female lizard swollen with eggs only if he is in the spring breeding condition. The physiological condition is influenced by environmental conditions, such as day length, which changes annually in a predictable manner. Therefore, when testing certain behavioral reactions to stimuli in animals, it is important to keep in mind the time of year and their physiological condition.

The behavioral response to specific stimuli (releasers) can range from very fixed (stereotyped) to highly variable. Generally, the degree of stereotype is dependent upon the level of integration that can occur within the central nervous system between the sensory input and the motor output. Thus, animals with more complex central nervous systems often exhibit less stereotyped behaviors compared with animals that have a simpler central nervous system. Those behaviors that are extremely stereotyped (i.e., fixed-action patterns) and that do not involve learning (i.e., modification by experience) are said to be instinctive. Very few behaviors are purely instinctive in that experience modifies their expressions. In this laboratory, students should learn basic concepts of behavior such as stereotype, instinct and learning. These instinctive behaviors are often adaptive--that is, they help (or helped) those organisms to survive or reproduce better than conspecific organisms without these behaviors. The study of behavior is one of the most popular of the biological disciplines, and is a frequent study area in psychology as well.

EXPERIMENTAL PROCEDURE:

Background: Many animals exhibit stereotyped behaviors that are adaptive. One example of this type of behavior is wall-seeking behavior in mice. This particular behavior is considered instinctive in that learning does not seem to be involved prior to its expression. To test the hypothesis that mice seek walls, two test groups will be established.

Hypotheses: Mice seek walls instinctively. Your hypothesis for the open arena is that mice will occur more often in edge squares.

Apparatus: A platform with a grid of 64 numbered squares with removable walls. 6 Mus musculus, same sex.

Experimental set ups:

1. Platform with four walls.

2. Platform with walls on two sides only.

3. Platform with no walls. Because any linear movement will eventually cause a mouse to come to an edge or wall in the other two designs, it might be interesting to know if this artifact of the design of our arenas will cause mice to seem to be 'edge-seeking' as well as wall-seeking.

Design: Six mice are to be placed on a platform (one mouse at a time) in each of 3 experimental set-ups and allowed to select positions through a period of 5 minutes. Positions of each mouse will be tallied at 5-second intervals. Tallies (a total of 120) will be divided into wall (i.e., tallies in which mice are in squares immediately adjacent to the wall), edge and non-wall/non-edge scores for each mouse. A Chi-Square test will be used to analyze data.

Theory and calculation of expected values: The object of the experiment is to compare the amount of time a mouse spends in the wall (W) squares (periphery) versus the amount of time it spends in the squares away (A) from the wall or the Edge (ED) and determine if it has a preference. Since the platform has 64 squares, perfectly random distribution of a mouse on the platform (120 observations) would allow a mouse 1.875 tallies per square (120/64). Thus, random distribution within the 28 peripheral squares would be 53 tallies (28 x 1.875) and 67 tallies (36 x 1.875) away from the periphery. These are the expected values (EV). In the second experimental set-up with two walls only, visualize an imaginary diagonal line that divides the board into walled and non-walled halves. What are the expected values, assuming random movements, for this experiment? You may use one of the squares that has both wall and edge as wall, and the other as edge. What are your expected values for the arena in which there were no walls? (here is the Bio 121 Chi square exercise if you need a reminder).

Procedure:

1. Divide into six groups and pick a mouse. Handle it gently by the tail. Don't startle it--even though these mice are wimpy lab mice and are used to being handled, startled animals may nip. Don't try to slap your hand down over it! Many a good mouse has been killed this way.
2. For each run, obtain a number from a jar containing 64 numbers to determine in which grid squareyou will first place each mouse.
3. Place a mouse in the appropriate square (one mouse at a time) and tally which square the mouse occupies at five-second intervals for a period of 10 minutes (120 observations total per mouse). Clean the floor of the platform with a damp paper towel after each mouse is tested.
4. Using the same mouse, move on to the next arena and repeat the procedure until all 6 groups have run their mice in all 3 arenas.
5. Set up a 3 Chi-square tables using the expected values you have already calculated.
   • What are your null hypotheses for each of the experimental runs?
   • Calculate experimental Chi-square values based on the combined class tallies for each of the 3 arenas.
   • Compare these values to critical values from a table.
6. Do you reject or fail to reject your null hypotheses for each of the trials?
7. Evaluate your biological hypotheses in light of your treatment of your null hypotheses.

Questions: Based on the results from the closed and partly closed arenas, do you think the design of the experiment, using such a small arena, makes the mice seem to be wall-seeking rather than actually being attracted to walls?

Why use mice of the same sex?

Why might wall-seeking behavior be adaptive?

Explain why we used both a closed and partially closed arena.

What are two reasons for replication in experimentation?

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