1.0 Title :
Natural
Selection Pressure Of Rabbits On A Specific Particular Area.
2.0 Aims :
1) To conduct an experiment using STELLA
Software.
2) To know how to make the stimulation
using STELLA Software.
3) To study how to integrate STELLA in
teaching and learning process.
3) To understand natural selection
pressure of rabbits on a specific area.
4) To study the relationship between the
predator and prey.
3.0 Introduction
Simulation is the applying of the
operation of a real-world process or system over time. The act of simulating
something first requires that a model be developed, this model represents the
key characteristics or behaviors of the selected physical or abstract system or
process. The model represents the system itself, whereas the stimulation
represents the operation of the system over time. Computer simulation is the
discipline of designing a model of an actual theoretical physical system,
executing the model on a digital computer, and analyzing the execution output.
Stimulation is used in many contexts such as simulation
of technology for performance optimization, safety
engineering, testing, training, education, and video games. Training
simulators include flight simulators for training aircraft pilots to
provide them with a life like experience.
Simulation is also used
with scientific modelling of natural systems or human systems to gain
insight into their functioning. Simulation can be used to show the eventual
real effects of alternative conditions and courses of action. Simulation is
also used when the real system cannot be engaged, because it may not be
accessible, or it may be dangerous or unacceptable to engage, or it is being
designed but not yet built, or it may simply not exist. Key issues in simulation include acquisition of valid
source information about the relevant selection of key characteristics and
behaviours, the use of simplifying approximations and assumptions within the
simulation, and fidelity and validity of the simulation outcomes. Simulation embodies the principle of learning by doing to
learn about the system we must first build a model of some sort and then
operate the model.
The use of simulation
is an activity that is as natural as a child who role plays. Children understand the world
around them by simulating with toys and figurines most of their interactions
with other people, animals and objects. As adults, we lose some of this
childlike behavior but recapture it later on through computer simulation. To
understand reality and all of its complexity, we must build artificial objects and
dynamically act out roles with them. Computer simulation is the electronic
equivalent of this type of role playing and it serves to drive synthetic
environments and virtual worlds. Less
theoretically, an interesting application of computer simulation is to simulate
computers using computers. In computer architecture, a type of
simulator, typically called an emulator, is often used to execute a
program that has to run on some inconvenient type of computer or in a tightly
controlled testing environment.
One
of the stimulation software is STELLA. STELLA is a computer program that is
created by Robert Webb of Australia. It is a system thinking for education and
research. Education and research are most exciting when student can move out of
the lecture room and library and provide opportunity to create, experience and
see. STELLA offers a practical way to dynamically visualize and communicate how
complex systems and ideas really work. STELLA is one of the simulation software.
STELLA can be use to stimulate a system over time. The stimulation made by
teacher can be repeated many times. It is also can jump the gap between theory
and the real world especially when teacher can show the experiment practically
instead of by theory only. By using STELLA, students are enable to creatively change
the systems. This is because STELLA provide a stimulation programme that enable
the user to vary the data in order to get the difference result of their
experiment.
By
using this simulation software, teacher can teach students to look for
relationships and see the big picture in it. Intuitive icon-based graphical
interface simplifies model building. Stock and flow diagrams that provided in
STELLA support the common language of systems thinking and provide insight into
how system work. STELLA is also used to clearly communicate system inputs and
outputs and demonstrate outcomes. Flight simulators and dashboards describe
model components and facilitate manipulation. The output devices highlight the
outcomes with warning flashers, text, graphs, tables and reports. Student will
be able to understand the experiment more clearly and the teaching and learning
process will be more fun. By using simulation in teaching process can help
teacher to explain the experiment more clearly thus can increase student
performance in the exam.
4.0 Results
In
this model, foxes prey on rabbits. Foxes catch the slower rabbits, which favors
an evolution over time toward faster rabbits. For the base case simulation the
bias are set to 20.
Graph 1 : Graph of simulation with
the bias speed set to 20 (normal).
|
Years
|
Average Speed Of Rabbits (ms)
|
|
5
|
6
|
|
10
|
12
|
|
15
|
18
|
|
20
|
24
|
|
25
|
24
|
|
30
|
24
|
From
the graph, we can see that the x-axis in the simulation graph is the years and
for the y-axis is the average speed of the rabbits. For the first five years,
the average speed of the rabbits is constant. There are no increase in average
speed of the rabbits yet as the rabbits still not evolved. Thus, in this phase,
the rate of birth of the rabbits is lower to the rate of death rabbits. This is
because, foxes prey on the rabbits causing the rate of birth of the foxes is
greater than the rate of death of the foxes. In this first five years, foxes
are able to catch and eat the rabbits as the rabbits run at slower speed
compared to the foxes. Less number of rabbits are survived causing the rate of
birth is lower to the rate of death of the rabbits. In the other hand, the rate
of birth of the foxes is higher than the rate of death of the foxes. This is
because of foxes consume on rabbits. Foxes run faster than the rabbits thus the
average speed of the foxes is higher than the average speed of the rabbits.
More rabbit die in this phase.
Then,
for the next five years which is ten years, we can see that the graph increase
rapidly. The average speed of the rabbits increase. This is because rabbits had
evolved from slow runner to fast runner. As time flies, rabbits evolved to
adapt with it surrounding environment. It has to run more faster to escape from
the predator which is the foxes. In this phase, the average speed of rabbits
highly increase. This natural selection pressure cause new rabbits born to
evolved into faster rabbits. The rate of birth of the rabbits is higher than
the rate of death of the rabbits. This is because, more faster rabbits can
survive from being eaten by the foxes. While for the foxes, the rate of birth
is lower than the rate of death. It is because, foxes that consume rabbits are
unable to catch the faster rabbits as the rabbits now have been evolved. Thus,
more fox die in this phase compared to the rabbits.
As
time increase, the graph of average speed of the rabbits become flatter. The
average speed of rabbits increase slowly. After the ten years, the newborn rabbits
start to stop from evolved. This is due to less foxes prey on rabbits as the
rabbits run more faster than the foxes. In this phase, the rate of birth of the
rabbits is equal to the rate of death of the rabbits. In the other hand, the
rate of birth of foxes also equal to the rate of death of foxes. As the rabbits
start to stop evolved and the average speed of the rabbits increase slowly,
foxes are able again to prey on slower rabbits. Foxes also may be undergo
evolution to prey on faster rabbits. But in this experimant, the fox evolution
thus not been take note because we only want to see the natural selection
pressure on the rabbits. Thus, in this phase, less number of rabbits are die.
However, there are also less number in newborn rabbits. Then we can say that
the rate of birth of the rabbits is equal to the rate of death of the rabbits.
Then, by using the STELLA Software, some
parameters are been added. The speed bias also be vary by decreasing it to 10.
Graph 2 : Graph of simulation with
the bias speed set to 10.
|
Years
|
Average Speed Of Rabbits (ms)
|
Rabbits Being Munched
|
Rabbits Being Born
|
|
5
|
3
|
100
|
80
|
|
10
|
6
|
95
|
90
|
|
15
|
9
|
90
|
100
|
|
20
|
12
|
85
|
110
|
|
25
|
15
|
80
|
120
|
|
30
|
15
|
75
|
130
|
From
the graph, we can see that some parameters had been added and the speed bias
had been decrease to 10. The x-axis in the simulation is the years taken by the
rabbits to evolve and at the y-axis is the parameters which is the average
speed of the rabbits, the number of rabbits being munched and the number of
rabbits being born. For the first five years, the average speed of the rabbits
is constant. There are no increase in average speed of the rabbits yet as the
rabbits still not evolved. The number of rabbits being munched is at higher
number during this five years. The number of rabbits being born is at the
lowest. This is because during this first five years rabbits do not evolve yet.
The lower average speed of the rabbits causing it to be easy to catch by the
foxes. Thus, in this phase, the rate of birth of the rabbits is lower compared
to the rate of death rabbits. In the other hand, the rate of birth of the foxes
is higher than the rate of death of the foxes. Foxes run faster than the
rabbits thus the average speed of the foxes is higher than the average speed of
the rabbits.
During
the next five years, the rabbits start to evolved. However, because of the
speed bias is changed into 10, the average speed of rabbits increase slowly or
less compared to the Graph 1. The number of rabbits being munched had decrease
and the number of rabbits being born increase. This is because of as the time
flies, rabbits evolved to adapt with it surrounding environment. It has to run
more faster to escape from the predator which is the foxes. In this phase, the
average speed of rabbits increase slowly as the bias speed is lower than the
normal. This natural selection pressure cause new rabbits born to evolved into
faster rabbits. The rate of birth of the rabbits is higher than the rate of
death of the rabbits. This is because, more faster rabbits can survive from
being eaten by the foxes. While for the foxes, the rate of birth is lower than
the rate of death.
As
the year increase, the average speed of the rabbits increase slowly and become
flatter. The number of rabbits being munched is decrease and the number of
rabbits born exponentially increase. After the ten years, all the newborn
rabbits had been evolved. This is due to less foxes prey on rabbits as the
rabbits run more faster than the foxes. In this phase, the rate of birth of the
rabbits is equal to the rate of death of the rabbits. In the other hand, the
rate of birth of foxes also equal to the rate of death of foxes. Thus, as the
natural selection pressure of the rabbits is decrease, the rabbits start to stop
to evolved. This shows why the average speed of the rabbits start to be flatter
as there are no more faster rabbits evolved. In this phase, the number of
rabbits at its maximum number.
For
the third graph, speed bias are change from normal to 30. The graph of average
speed of rabbits, number of rabbits being munched and the number of rabbits
being born are being studied.
Graph 3 : Graph of simulation with
the bias speed set to 30.
|
Years
|
Average Speed Of Rabbits (ms)
|
Rabbits Being Munched
|
Rabbits Being Born
|
|
5
|
8
|
105
|
100
|
|
10
|
16
|
100
|
200
|
|
15
|
24
|
95
|
300
|
|
20
|
32
|
90
|
400
|
|
25
|
40
|
85
|
500
|
|
30
|
40
|
80
|
600
|
In
the third graph, we can see the pattern of the graph is almost the same for all
of the graph. However, the differences between all the graph is how steeper and
flatter the graph due to difference speed bias that had been applied. For the
last graph, we can see that for the first five years, the graph is constant.
There are no increase in average speed of the rabbits. In this phase, rabbits
not being evolved yet. The graph for rabbits being munched is the constant and
highest while for the graph of rabbits being born is constant and at the lowest.
Thus, the rate of birth of the rabbits is lower compared to the rate of death
of rabbits. In the other hand, the rate of birth of the foxes is higher
compared to the rate of death of the foxes. This is because at this phase, foxes
prey on rabbits as the rabbits can not run faster. Foxes run faster than the
rabbits make it easy to caught the rabbits. Thus, increase the number of death
rabbits and lower the rate of birth of the rabbits.
For
the next ten years, the average speed of rabbits is increase. The number of
rabbits being munched is decreasing a lot or steeper. While the number of
rabbits being born is increasing. At this phase, we believe that the rabbits
have undergo evolution process due to the natural selection pressure. The
rabbits had transform from slower rabbits into faster rabbits. This is due to
the foxes prey on slower rabbits. Thus, the newborn rabbits is evolved into
faster rabbits as it is adopt to its surrounding. The rabbits have to protect
itself from the foxes since it is small. As the time flies, the rabbits evolved
itself into the more faster rabbits. In this phase, foxes unable to caught the
faster rabbits. Thus, the rate of birth of the foxes is lower compared to the
rate of the death. The rate of birth of the rabbits is higher than the rate of
death.
After
ten years, the average of speed of the rabbits increase slowly. The average
speed is still increase but not rapidly as ten years ago. This is because
rabbits feel safe after being evolved so rapidly. Foxes can not caught the
faster rabbits. However, foxes also can be evolved in order to get their food
and maintain it population. The number of rabbits being munched is decrease and
the number of rabbits born exponentially increase. After the ten years, all the
newborn rabbits had been evolved. This is due to less foxes prey on rabbits as
the rabbits run more faster than the foxes. In this phase, the rate of birth of
the rabbits is equal to the rate of death of the rabbits. In the other hand,
the rate of birth of foxes also equal to the rate of death of foxes. Thus, as
the natural selection pressure of the rabbits is decrease, the rabbits start to
stop to evolved.
5.0 Discussion
Natural selection is the gradual, non-random process by which biological traits become either more or less common in a population as a function of differential
reproduction of their bearers. It is a key mechanism of evolution. The term natural selection
was popularized by Charles Darwin who intended it to be compared with artificial selection, what we now call selective breeding. Variation exists
within all populations of organisms. This occurs partly because random
mutations cause changes in the genome of an individual organism, and these mutations
can be passed to offspring. Throughout the individuals lives, their genomes
interact with their environments to cause variations in traits. Individuals
with certain variants of the trait may survive and reproduce more than
individuals with other variants. Therefore the population evolves.
Factors that affect reproductive success are also
important, an issue that Charles
Darwin developed in his ideas on sexual selection, for example. Natural
selection acts on the phenotype,
or the observable characteristics of an organism, but the genetic basis of any phenotype that gives a
reproductive advantage will become more common in a population. Over time, this
process can result in populations that specialize for particular ecological niches and may eventually result in the emergence of new species. In other
words, natural selection is an important process by which evolution takes place
within a population of organisms. As opposed to artificial selection, in which
humans favour specific traits, in natural selection the environment acts as a
sieve through which only certain variations can pass.
An experiment was conducted using STELLA Software to
understand the relationship between the prey and predator of the rabbits and
the foxes. This simulation also being used to observe the average speed of
rabbits when different speed bias is applied. As the rabbits undergo natural
selection pressure, the average speed of the rabbits will increase. There are
some other parameters are being added to see the variation of the graph. The
number of rabbits being munched will be decrease as the rabbits now be able to
protect itself from the predator. The number of rabbits being born will be
increase as the rabbits can grow until it is matured to breed more rabbits. Thus,
when the rabbits being evolves, the rate of birth of the rabbits will be
greater than the rate of death. Meanwhile, when the rabbits being evolves, the
rate of birth of the foxes is lower than the rate of death.
Model
structure of the life cycle of the rabbits.
6.0 References
http://en.wikipedia.org/wiki/Natural_selection
(retrieved on 16/11/2012)
http://en.wikipedia.org/wiki/Simulation_software
(retrieved on 16/11/2012)
http://en.wikipedia.org/wiki/Simulation
(retrieved on 16/11/2012)
http://rationalwiki.org/wiki/Natural_selection (retrieved on 16/11/2012)
http://www.cise.ufl.edu/~fishwick/introsim/node1.html
(retrieved on 16/11/2012)
http://www.iseesystems.com/aspx/WebLogin.aspx
(retrieved on 16/11/2012)
