The  Model

 The Inquiry  Process: The Model

Overview:  Introduction

What follows in the next six sections is a step by step outline of an investigation of animal behaviour using the inquiry method. 
The authors have used grooming behaviour of the fruit fly Drosophila, but this exercise should be adaptable to many different species and behaviours. 

Such an experience will give students more input into the direction of the work, capitalizes on their prior knowledge, forces them to make decisions about experimental design and analysis, and challenges them to interpret data without depending on preconceived notions of what the “right” answer should be.

Each of the following sections will outline the general procedures used in this type of exercise.  The specific example using Drosophila and grooming behaviour will be presented in parallel links to other pages.

The Example
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Step One.  A Simple Question:  How do we study the behaviour of an animal?

1.  Present the student with this simple question.  Help students bring their own experiences to this problem. Students will know much more about animal behaviour than they first realize.  Depending on their level and background, comments from students will include:

Define different kinds of behaviour (feeding behaviour, locomotion, sexual behaviour, etc.)
Different methods of studying behaviour (field studies vs. lab studies, experimental manipulations vs. direct observations)
Using different animals (here you may suggest the behaviour of plants can also be studied)

2. Discuss the considerations involved in selecting a behaviour and an animal model for study.

This discussion can include issues of the particular questions being asked, cost, care and housing of animals, ease of handling, techniques and equipment needed for the study.  Stress at this point that simple questions and simple experiments can be just as valuable as costly and complex experiments.

3. Discuss the first steps in a study of animal behaviour (or any other study).

Here help the students realize they already know a great deal about the behaviour of many animals (pets, movies, zoos, friends, and parents).  What do they need to do to learn more about the basic behaviours of an animal?  Stress the critical importance of careful observations.  Use examples of scientists who have become “famous” by using their powers of observation (e.g. Jane Goodall, Charles Darwin, Wright brothers, Copernicus).

4. Select the animal for your exercise.

Using the previous discussion have the class, group, or teacher select the animal which will best suit the interests, facilities, and time available.  The authors used the fruit fly Drosophila because of its ease in handling, availability, large amount of background knowledge, etc.

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Step Two.  The Ethogram: The Baseline Information For All Other Studies.

An ethogram is a catalog of an animal's (or species') behaviour (Lehner, 1996).  It includes descriptions of the types of behaviour an animal displays (feeding, locomotion, fighting, sexual, parenting).  Ethograms can also be more refined and catalog the detailed motor patterns involved in these general categories of behaviour.  This exercise will focus on the grooming behaviour of Drosophila , but other behaviours may also be suitable for class study (spider web construction, territorial behaviour of fish, feeding behaviour of students in the cafeteria).

Discuss with students the concept of an ethogram.  An analogy to a glossary may be appropriate here. An ethogram is a glossary of the animals behaviour providing the names and descriptions of the animal's behaviour.  Elicit from students the obvious need for common terms and descriptions in an ethogram (as in the binomial system of classification).  The basic ideas of building an ethogram are simple and straightforward.  First students will need to decide how to observe the animal (single animal or groups, free ranging or confined, directly or using video or other technology).  Secondly, the students will need to decide how to record their observations (tape recording, video recording, etc.).  These considerations sound simple, but students will soon realize many complications and questions will need to be resolved before they can get consistent and reliable data.

1. Once the setup issues have been resolved ask individual students to spend time observing the animal.  Have them record the “different kinds” of behaviour they see the animal perform.  Let them define their own categories, but insist they write a description that is specific enough to be recognized by other students.

2. Have students compare their first ethograms and come to a common consensus for the number of different behaviours, their names, and descriptions.  There will be students who classify general categories of behaviour (feeding, walking, and grooming) and those that describe more detailed behaviours that belong to the more general categories (grooming the front legs, grooming the wings).  This can lead to a discussion of which questions may be appropriate for general descriptions and others for more specific descriptions.

3. If a particular behaviour such as grooming is to be studied in detail, an ethogram of that behaviour must be produced.  Use the same method described above.  This time have the students restrict their observations and descriptions to behaviour belonging to the selected category of behaviour.

4. In this exercise the grooming behaviour of flies will be studied.  However, the teacher should feel free to choose other behaviours to study or let students suggest directions.  Grooming behaviour is used here because it is obvious, has a number of easily recognized components, and can be manipulated with several variables.

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Step Three:  Quantitative Analysis of Behaviour.

The construction of an ethogram works well to hone the students' appreciation of the need for accurate and consistent observations.  The teacher may limit this exercise to the ethogram.  However, it is important to point out to students that little or no quantitative information can be found in the ethogram an ethogram.  Animal behaviour is no exception to the need to characterize data with quantitative techniques (Lehner, 1996 and Douglas, 1979).

1. Ask students what other kinds of observations they could make in addition to the ethogram. Suggestions will probably include:

How often the animal engages in each behaviour (frequency)?
How long the animal engages in each behaviour (duration)?
How do the different behaviours appear in sequence relative to one another (temporal distribution)?

2. Discuss with students how they could obtain these different types of data.  Most school situations will make measuring duration difficult if the behaviours are performed in quick sequences.  However frequency and temporal distribution are more accessible to students. A commonly used technique in animal behaviour studies to analyze sequences of behaviour is called Markov chain analysis, which uses the common Chi-Square statistical test. What is required is a recording of the sequences of behaviour displayed by the animal in the order they occurred.  This is best done by having students use a tape recorder to record the data as they observe the animal.  Video recording has the advantage of permitting students to review the same sequence of behaviour over again.  The teacher and students will find that they will have to be creative and work well together to record this type of data.

 3.  In brief, a Markov chain analysis consists of counting how many times each of the behaviours in the ethogram is followed by each of the other remaining behaviours in the ethogram.  This produces a table of  “transition frequencies”.  The Chi-Square test can be applied to the transition frequency table to determine which pairs of transitions are more or less commonly observed than would be expected if the behaviours occurred at random. In other words, the Chi-Square test will confirm which behaviours show a higher (or lower) probability of forming paired sequences.  This will reveal patterns of sequences that characterize the behaviour (Lehner 1996 and Dawkins, 1976).

4. Once the Markov analysis is done, have the students spend time discussing the “structure of the behaviour”.  This is one level of analysis above the ethogram.  Students will quickly realize that the behaviour of their animal is not a random collection of events, but shows patterns of very predictable sequences of behaviours. For example in grooming behaviour of flies, they most often begin by grooming the head and mouth parts for a period of time before grooming the wings or abdomen rather than randomly grooming different parts of the body.

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Step Four:  Experimental Manipulation of Behaviour .

The ethogram provides the “dictionary” or “vocabulary” of the behaviour.  The Markov analysis provides a degree of quantitative description by relating the behaviours to one another.  These approaches may suggest hypotheses for explaining the controlling mechanisms of the behaviour.  However, animal behaviour is no different from any other area of science and can be studied by manipulating experimental variables and comparing results to controls (Tinbergen, N. 1956).  If the teacher expects to carry this exercise to this level of analysis, some background will probably be necessary for the students. If students have not studied the scientific method, this is an ideal place for its introduction.

Examples of this level of analysis can be found in any textbook of animal behaviour.  They include studying behaviour by changing levels of hormones that influence reproductive behaviour, manipulating stimuli used for orientation, and altering genes that control mating behaviour.  Having students suggest ways to do this with their animal may be difficult.  They will generally have limited knowledge to use at this point.  Experimental manipulations with species used may present difficult technical, financial, or ethical problems.  Using an insect such as Drosophila eliminates many of these difficulties.

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Step Five: Extension/Reinforcement?  Additional Ideas
This type of open ended laboratory exercise will suggest a variety of alternative options and extensions to students.  Remind students they have access to several sources of animal behaviour data.  Movies such as Jurassic Park, Lord of the Flies, and Anne Hall have interesting sequences of animal and human behaviour.  NOVA and Discovery videos are available in many libraries. Discuss with students where they might find other examples of animal and human behaviour.  The example used in this exercise uses individual animals.  The same techniques can also be used to study interactions among groups of animals.  Students have an intense interest in social behaviour that the teacher can tap into for this exercise.

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Step Six: Evaluation/Assesment
A long term project such as this can utilize a number of different types of assessment tools for students and teacher.  In addition to the standard lab report format consider capitalizing on students interests.  Art projects can be used to illustrate the different behaviours in the ethogram.  Students in drama groups can find ways to act out the behaviour sequences they discover in the transition matrix.  Rather than waiting for the end of the students' work, assessing their progress during the course of the project can provide students with timely feedback they can respond to before submitting their final report.  This can be done in a variety of ways such as having student submit progress reports at the end of each phase of the project, grading students in class based on their group performance, etc. Rubrics for all stages and forms of assessment will give students and teacher a clear understanding of the expectations during the course of the study.

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The Inquiry  Process: The Example

Overview:    Animal Behaviour

Animal behaviour can be studied at several levels of analysis (Lehner, 1996, Hinde 1970).  The most fundamental objective must be the initial description and cataloging of the behaviours (making an ethogram).  Once a well defined ethogram has been established, quantitative and statistical techniques can be used to analyze the temporal sequences and frequency distribution of the behaviours.  Finally, the scientific method can be used to manipulate experimental variables to produce an understanding of the mechanisms controlling the expression of the behaviour.

In this experiment the grooming behaviour of the fly Drosophila melanogaster will be studied at three levels of analysis.  First, an ethogram of the behaviour will be constructed through direct observation of the flies.  Second, statistical analysis including Markov Chain Analysis and Chi Square testing will be used to characterize the temporal sequences and patterning of  grooming behaviour.  Finally, the use of surgical and genetic manipulations will be used to test a hypothesis concerning central nervous system control of this behaviour.

The Model
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Step One:  How do Drosophila Groom?

The grooming behaviour of insects, including flies, has been studied by several authors (refs).  Grooming in these insects is a stereotypic behaviour characterized by a predictable sequence of behaviours which often occur in cyclical bouts (ref).  Several authors have suggested that the patterns in stereotypic behaviour such as grooming are strongly controlled by the nervous system.  External stimuli may initiate, terminate, or influence the intensity of the behaviour, but not the overall patterns of the behaviour (refs).  Therefore only experimental manipulations which effect the nervous system will alter the patterns and sequences of the behaviour.

In this experiment, the grooming behaviour of Drosophila melanogaster will be studied.  Comparisons will be made among three groups.  The groups will include normal wild type flies, normal wild type flies with their wings removed, and wingless flies with the mutation "vestigial wings".  The hypothesis is the patterns of grooming behaviour will not be altered by removal of the wings since the neurons of the central nervous system controlling grooming remain intact.  An additional hypothesis is the patterns of grooming behaviour will be altered by the vestigial mutation due to developmental consequences of this mutation.

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Step Two:  Build an Ethogram.

This example uses the fruit fly Drosophila melanogaster .  This species is easy to obtain and care for.  Its wide spread use in genetic studies opens the possibility of using various mutant strains in behaviour experiments.  Materials need to maintain stocks of Drosophila are readily available from biological supply companies.  When using an animal as small as Drosophila , some consideration of the equipment needed for observing  the specimen and recording data.  In this case the authors used dissecting microscopes to observe the flies in small closed containers.  Data was recorded by the observer with a audio tape recorder as the fly groomed.  The behaviour was also recorded using a VCR connected to the microscope via a "flex cam".

Simply finding the best methods for observing and recording the animal's behaviour can be a valuable experience for the students.  Each species will present its own particular responses to handling.  In the case of Drosophila , the flies responded best when kept in containers which were at least a centimeter in diameter.  Flies in smaller containers spent most of their time attempting to escape.  Eliciting grooming behaviour was also found to be enhanced when ether was used to disable the flies during handling.

At total of fifteen different grooming behaviours were observed.  Although these are presented as separate and distinct behaviours, there are instances where the fly appears to be producing intermediate forms of the behaviour.  The process of deciding what behaviours constitute grooming and distinguishing among these various behaviours is an important lesson for students.  Producing consistent and reliable descriptions of behaviour requires careful observation and discussion among the participating students. See Dawkins, 1976, and Armstrong, 1985 for similar studies. Grooming Behaviour Ethogram of Drosophila melanogaster


Fly Grooming Front Legs and Head. 


Fly Grooming Abdomen, Wings, and Rear Legs. 


Wingless Fly Showing Grooming Behaviour of the Missing Wings. 

Click on the images above to view a short movie of the grooming fly.  Warning! These are large files and may take some time to download

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Step Three: Transition Matrix and Markov Chains.

Once the ethogram was constructed, additional observations were taken to record the sequence in which these behaviours followed one an other.  A typical sequence for a normal wild type Drosophila is given below.  This is not a complete sequence.  A complete sequence can include several hundred observations if the fly is grooming intently.

F-H-F-H-F-H-F-H-F-H-F-H-F-H-(stop)F-H-F-(stop)-F-T-FR-F-(stop)-F-H-F-H-R-A-R-A-UL-R-UL-R-UL-R-UL-R-
UL-R-UL-R-UL-R-UL-R-OL-R-A-R--UL-R-UL-R-------

Sequences of data were recorded for two normal wild type flies.  A transition matrix was constructed for both using the following procedure.  The example given below is a matrix for the two normal flies combined.  This was done because the matrix for both flies were very similar, and pooling data improves the quality of the statistical analysis done later.

Transition Matrix for Two Normal Wild Type Drosophila Preceding Behaviours

.

F

H

T

FR

FL

OR

OL

OB

UR

UL

UB

RR

RL

A

R

totals

F

.

338

10

4

3

.

2

.

.

1

.

1

.

1

4

364

H

340

.

8

5

.

.

.

.

.

.

.

.

.

.

2

355

T

11

6

.

.

.

.

.

.

.

.

.

.

.

.

2

19

FR

.

.

1

.

.

.

.

.

.

.

.

1

.

.

1

3

FL

.

1

.

.

.

.

.

.

.

.

.

.

.

.

.

1

OR

.

.

.

.

.

.

12

4

.

4

2

.

.

2

6

30

OL

.

.

.

.

.

13

.

9

2

4

.

.

1

3

3

35

OB

.

.

.

.

.

2

2

.

2

3

5

.

.

1

7

22

UR

.

.

.

.

.

2

.

.

.

1

.

1

.

2

9

15

UL

.

.

.

.

.

1

7

.

.

.

.

.

1

34

71

114

UB

.

.

.

.

.

2

2

3

.

1

.

1

.

3

2

14

RR

.

1

.

.

.

1

1

.

.

1

1

.

.

1

2

8

RL

.

.

.

.

.

.

.

.

.

.

.

1

.

.

7

8

A

1

.

.

.

.

3

3

.

.

9

.

1

2

.

86

105

R

3

2

.

.

.

4

.

6

12

89

7

2

4

99

.

228

totals

355

348

19

9

3

28

29

22

16

113

15

8

8

146

202

1321


Several things can be observed directly from this table.

A Chi-Square can be used to test this table.  A significant P value for the Chi-Square of a cell means the transition from the preceding behaviour to the following behaviour occurred with a greater or smaller frequency than would be expected if the transitions were occurring at random.  The large number of empty cells in this table guarantees a significant Chi-Square value for many of the cells and therefore is not particularly useful.  More data would help this problem, but may not be feasible for a school exercise.  A more informative analysis is to break this large table into sub-tables.  The table below condenses the transition matrix into cells which fall into three categories: Grooming using the Front Legs, Grooming the Wings, Grooming using the Rear Legs but not the wings. Preceding Behaviours

 

Front Legs

Wings

Rear Legs

Totals

Front Legs

obs =727 
exp =(412), X 2 =  240

3 
(125)  119

12 
(204)  181

742

Wings

0 
(128)  128

83 
(38.8)  50.3

147 
(63.4)  110

230

Rear Legs

7 
(194)  180

137 
(58.9)  103

205 
(96.2)  123

349

Totals

734

223

364

1321

The expected values in the Chi-Square table are calculated by multiplying the corresponding row and column totals for each cell and dividing by the grand total.  The expected values are in parentheses in the table above.  The Chi-Square for each cell is calculated by the standard formula (observed value-expected value) 2 /(expected value).  If the Chi-Square is greater than the value listed in a Chi-Square table with two degrees for freedom (number of behaviours minus 1) at the 0.05 level, then the transition in the cell is significantly greater or less than would be expected if the behaviours are randomly sequenced.  In the table above the Chi-Square must be greater than 5.99 to be significant. The Chi-Square values are in blue in the table above.

The transition matrix table above shows that all of the cells have a significant Chi-Square value.  Closer examination reveals that the Front Legs transition to Front Legs much more than expected and much less to the Wings or Rear Legs than expected.  The Wings transition significantly more than expected to Wings and Rear Legs, and significantly less to Front Legs.  Similarly, the Rear Legs have significantly high transitions to Rear Legs and Wings, but a significantly reduced transition to Front Legs.

In other words, when a fly is grooming the front part of its body, it tends to alternate among the various behaviours associated with the front of the animal (F, H, T, FL, FR) and avoids shifting grooming to the wings or rear part of the body.  Grooming of the remaining parts of the body is more complex.  When grooming the wings, the fly will tend to continue grooming the wings or it will shift to the rear elements.  In the same way, when grooming the rear elements, the fly will tend to continue grooming the rear or shift to the wings.

If a Chi-Square analysis is made over the entire transition matrix the following patterns emerge:

It was also observed that when a fly started grooming, it usually began by grooming the front part of the body before moving its attention to the rear body parts.

 

 

 

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