This model shows the interactions between species and environmental factors at different desert trophic levels. This model will allow the user to identify how the different limiting factors of rainfall and temperature affect the populations of desert species and the energy transferal between each species based on environmental factors.
Organisms: Cacti, butterflies, lizards, snakes
Limiting Factors: Rainfall and temperature
The graphs in this model include 'Rainfall and Temperature Over Time', which is indicative of the 'Rainfall' and 'Temperature' sliders; the graph 'Populations Over Time' that tracks the number of organisms in each species' population the model's run time; 'Energy Over Time', which displays the total cumulative energy and the energy of each individual heterotrophic species as it rises and falls through the model; and 'Birth and Death Rates', which displays the cumulative, total birth, and death rates of all species in the model.
Contrary to an actual ecosystem, no species will go extinct completely. There are coded 'survivors' that will continue the model should there be more observations to make.
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This model includes four trophic levels of a desert biome. The first level are producers, represented by cacti. Cacti, suited to their environment, are able to withstand low rainfalls and extreme temperatures, so when the limiting factors of rainfall and temperature are toggled, there should be a minimal change in the cacti population.
The plants are food for the butterflies living in the desert, in this model represented by the general butterfly. As primary consumers, the butterflies consume the producers and their nutrients as well as their stored water. When there is a surge of cacti, the butterfly population will follow in reaction. Additionally, high rainfall is beneficial to the butterfly population, as reproduction rates increase phenomenally when there is a high amount of rain. Extreme low temperatures will cause the butterfly population to decline, as butterflies and their reproduction rates are particular to the cold. The limiting factor will make it so that the butterfly population may not surpass 150.
The secondary consumers are the desert lizards who prey on the butterflies. As thermoregulation is one of their prime features, the limiting factor that has most impact on lizards would be temperature. They become more active during higher temperatures, which increases their reproduction rate and overall population. With too low of temperature and low rainfall, the lizard population will decrease. Following a surge of butterflies, the lizard population will see phenomenal growth, and as per the reaction, will drop along with their food source. In this model, they are also marginally impacted by amount of rainfall. The limiting factor will make it so that the lizard population may not surpass 40.
The tertiary consumers represented in this model are desert snakes. As snakes are unable to live where the ground is frozen year round, too low of temperature would be detrimental to their populations. Alternatively, higher temperatures will reveal a rise in the snake reproduction rates and populations, also impacted by their food source, the lizards. Snakes conserve their main energy, only active when necessary, so their overall rate of growth will be more gradual than other species at different trophic levels. They are also marginally impacted by amount of rainfall in this model. The limiting factor will make it so that the butterfly population may not surpass 10.