Simple predator


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Simple predator

  1. 1. Simple Predator-Prey Dynamics Using STELLA.1.0 Introduction STELLA is a program computer that was created by Robert Webb of Australia. Theprograms can be manipulated and altered in various ways. The STELLA software can beuse from isee systems to model dynamic systems. Dynamics systems are usually verycomplex, having many components with involved relationships. STELLA offers a practicalway to dynamically visualize and communicate how complex systems and ideas really work.For example, STELLA can be used to model competition among different species for limitedresources or the chemical reactions of enzyme kinetics. Moreover, thousands of educators and researchers have made STELLA to studyeverything from economics to physics, literature to calculus, chemistry to public policy andmore interesting and unique STELLA has capabilities to stimulate learning. This is becauseSTELLA allows user to communicate how a system works, how the systems is impacted andwhat are the outcomes. STELLA is a flexible computer modelling package with an easy,intuitive interface that allows users to construct model and simulation. The model representsthe system itself whereas the simulation represents the operation of the system over time. In addition, STELLA also can give supports in diverse learning styles with a widerange of storytelling features. Students have variety of learning style such as auditorylearners, visual learners, tactile learners and kinesthetic learners. Everybody learns in theirown way. So, for visual learners STELLA can help in making learning more awesome andinteresting because students with visual learners learning style can discover relationshipsbetween variables in an equation by using diagrams, charts and animation that can be foundin STELLA software. Visual learners will be able to recall what they see because they mostlylearnt by observing and enjoy working with graphs, computer graphics, graphic organizersand text with a lot of pictures. So, STELLA is the best choices for this kind student’s learningstyle to generate them be active in learning, improve their grades and make study becomemore enjoyable. Besides, STELLA auditory or verbal learner might surround visual models with wordsor attach documents to explain the impact of a new environmental policy. STELLA alsosuitable for student’s learning style kinesthetic and tactile learners. This is because STELLAgives user an enormously powerful and flexible tool for creating environments that allowpeople to learn by doing. Then, auditory learner also can use STELLA software in learning 1
  2. 2. because it has multimedia supports for graphics, movies, sounds and text messages.Overall, STELLA can be use to simulate a system over time, jump the gap between theoryand the real word because students can be able experience by their self to make experimentand understand the theory by using STELLA. In addition, STELLA also enables students to creatively change systems and teachthem to look for relationships based on the diagrams or graphs that appear based on theexperiment they run. This is because STELLA can clearly communicate system inputs andoutputs and demonstrate the outcomes. So that students can more understand the variablesthat influence their experiment and make learning become more effective. However,STELLA not only used for run an experiment but STELLA has widely functioned such asbuilt-in functions to facilitate mathematical, statistical and logic operations. There are some benefits by using STELLA software which is the language increasesthat accuracy and clarity of verbal descriptions, ambiguities diminish and communicationmuch more efficient and effective. Besides, the software provides a check on intuition andalso provides a vehicle for building an understanding of why. The tools facilitate puttingtogether in an organized and clear way the qualitative and quantitative approaches presentin the experiment. Moreover, the tool enablers an easier operation, demonstration serving asthe basis for analyzing different types of infrastructure. STELLA is one kind of simulation that useful in teaching strategy for illustrating acomplex and changing situation. Nowadays, simulation in education is widely becomerecognized as an important tool in schools and being used as medium instructional.Simulation is also used to gain insight into their functioning and show the eventual realeffects of alternative conditions and courses of action. Next, simulation also used when thereal system cannot be engaged because it may no be accessible or may dangerous andunacceptable to engage. The main point using simulations include acquisition of validresource information about the relevant selection of characteristics, behaviours and validityof the simulation’s outcomes. In additions, simulations promote student’s critical and evaluative thinking. This isbecause STELLA simulations will encourages student think beyond of their mind andgenerate analysis thinking. Besides, there are several benefits that students get by usingsimulation of STELLA. For example, through simulation will include the participation ofstudents while using the software and promotes the constructivism learning. When studentsdirectly involved the learning process will be more enjoyable and students acquire moreknowledge and understanding. Next, simulations are necessarily less complex compare topresent the real situations. This is because students are not necessarily to observe the 2
  3. 3. interaction between prey and predator for several days in the real situation. In contrast, byusing stimulation of STELLA, just need to run the experiment in more comfortable and safetyenvironment compared to the real situation that used more student efforts and put them indanger condition. Furthermore, observe the interaction between prey and predator in the real situationwill cost more than running experiment using STELLA simulation. Sometimes, it is notworthless and may cause waste of time and cost because the result students can get fromobserve the real situation will end up to nothing and make them low in motivation anddisappointed in study. This is because is not easy to estimate and predict the interaction ofliving thing which human cannot control their activity. In contrast, by using STELLAsimulation are often cheaper and low in cost needed. For example, install simulationsoftware is cheaper than buying parameters to measure the interaction between prey andpredator in the real situations. Besides, simulations can be paused meanwhile the real life cannot. Pausing allowsmore time for students to assess what’s going on. So, the learning process will be moreeffective to the students. The purpose simulation in teaching and learning is gives deeplearning. This is because by using simulation engage students in deep learning thatempowers understanding compared to the learning by using text book which only willpromote students commit to memorize without understand the content. Moreover, simulationwill stimulate learner’s curiosity and create their interest toward learning process. Most importance, simulations allow students to change parameter values andobserve the changes occurred after parameter is change. For example, size in one time lynxharvest is the parameters change to see what happened in the hare population. Simulationsalso teach students to think like scientist does. Next, simulations also help studentsunderstand the scientific knowledge that rely on the acceptable hypothesis. Then, studentsalso can improve their understanding on probability and sampling theory by using simulation.Interestingly, students can predict outcomes using simulations and make learning processshowed the progress. On the other hand, the curiosity of students will lead them to explore and satisfy theircuriosity. So their will self motivated to run an experiment and exposed themselves toinvestigate the variables that influences the changes to occur in the experiment. Simulationsalso can improve students’ ability to apply particular concepts in problem solving. Whenstudents can solve the problem actually they already develops their creative thinking andlearning process will be more effective and beneficial. 3
  4. 4. 2.0 Content of STELLA (Simple Predator-Prey Dynamics). A predator is an organism that consumes another organism. While the prey is theorganism which predators eat. For example, in this simulation by using STELLA software,the lynx is the predator and prey refer to the hare. Predator and prey are evolving together.The prey is part of the predator’s environment and the predator will die if it does notconsume food. So, predator evolves whatever is necessary in order to eat the prey.Likewise, the predator is part of the prey’s environment and the prey dies if it is eaten bypredator. So, it evolves whatever is necessary to avoid being eaten. A population is refers to the group of organism of the same species that live in thesame area at the same time. The predators tend to regulate the prey population or viceversa. While populations ecology is study of how members of a population interact with theirenvironment. Moreover, population ecology considers the number of individuals of aparticular species that are found in an area and the dynamics of the population is study thechanges in population on how and why those numbers increase or decrease over time. However, population growth is a change in the number of individuals in a population.Positive growth occurs when the number of individuals in a population increases. Whereas,negative growth occurs when the number of individuals in a population decreases. Factorsthat effect on the rate of population growth are birth rates, death rates, immigration andemigration. Birth rates or known as natality is the addition of organism to the populationthrough reproduction that will cause the population growth to increase. While, death rates orknown as mortality is lose of organisms from the population due to death. This death rate willcause the population growth to decrease. In addition, a population’s growth rate (per capita increase) equals birth rate minusdeath rate. Zero population growth will occur when birth rate is equal to death rate. Themaximum number of offspring that an organism can produce under ideal conditions knownas biotic potential. The ideal condition allows a maximum birth rate and a minimum deathrate. Biotic potential cannot be sustained because some form of environmental resistancewill eventually limit further population growth. Biotic potential can determines the agebeginning of reproduction, how often reproduction occurs and how many offspring are bornat a time. Environmental resistance refer to the combination of biotic and abiotic factors thatlimit the size of the population. When populations become large, they tend to run out ofsome limiting resource such as food, water, light, oxygen and space. When this situationoccurred, it will limit further populations growth and pushes down on a growth curve. Thus, 4
  5. 5. prevent populations from growing exponentially or achieving their biotic potential. Thebalance between biotic potential and environmental resistance defines the carrying capacityfor a particular organism with a given set of environmental resources. The carrying capacity is the maximum population size that can be sustained over arelatively long period of time by a particular environment. Once population growth slows andmaintains a nearly steady level the population is said to be at the carrying capacity for theenvironment. The constant population rarely exist. Actually, population numbers fluctuatebecause conditions within habitats constantly change due to predation, competition,diseases and seasonal, climatic differences which affect the availability of light, water andfood. Moreover, carrying capacity often serves as the basis for sustainable development. Ifcarrying capacity exceeded, living organisms must adapt to new levels of consumption orfind alternative resources. Next, natural selection favors more effective predators and more evasive prey. Thismean predators such as lynx that have dominant characteristics like agile in hunting prey likehare will survive longer than lynx that weak in hunting because they must have enoughresources to survive and breed. Prey that evasive means that hare which be able to avoidfrom being killed by predator. The evasive hare will survive and breed for the continuous lifespan. Based on the theory, when prey are numerous their predators increase in numbers.While, reducing in prey population will cause the number of predator to decline. The preypopulation eventually recovers, starting a new cycle. 5
  6. 6. Results:Based on the graph above, when the size of one time lynx harvest is equal zero the systemin stable condition with both lynx and hare in a balance such that for each population, birthsis offset by deaths. 6
  7. 7. Based on the graph above, when the size of one time lynx harvest is equal 90, the system inunstable condition between lynx and hare in an imbalance such that for each population.The population of hare have a little bit changes compare when the size of one lynx harvestequal to zero. This is because predators (lynx) tend to regulate the prey (hare) populationand vice versa. So, by this simulation students can repeat anytime and can explore theexperiment to get information on how the changes will occur. 7
  8. 8. Based on the graph above, when the size of one time lynx harvest is equal 380, the systemin unstable condition between lynx and hare in an imbalance such that for each population.The graph showed that greater lynx consume hare compare graph before this. The numberof hares killed per lynx per year is assumed to depend on hare density. The greater densityof hares in the ecosystem, the larger the number of hares consumed per lynx per year. 8
  9. 9. Based on the graph above, when the size of one time lynx harvest is equal 640, the systemin unstable condition between lynx and hare in an imbalance such that for each population.The graph showed that greatest lynx consume hare compare other graph. However, at initialof the graph showed lynx sudden drop and more lynx die. More precisely, some fraction ofthe lynx populations dies each year. The fraction is determined by the density of the harepopulation in the ecosystems. A higher density of hares means fatter, happier and longer-lived lynx. On the other hand, as population density of hares declines, a larger portion of thelynx population will die of malnutrition and starvation. 9
  10. 10. Conclusion: Based on the experiment predator-prey dynamics, using STELLA simulation actuallyallow students to change parameter values and observe the changes occurred afterparameter is change. Moreover, students understand the concepts when the number ofhares killed per lynx (per year) increases with the density of hares in the ecosystems.According to understanding, the most important part is promotes student’s critical andevaluative thinking and at the same time student be able to make prediction for the outcome.For example, when density is zero means there is no hares, so kills per lynx per year mustbe zero. Lastly, when students can make prediction they will feel happy to learn somethingand make the learning process more effective. 10